WO2009038591A1 - Bile salt colloids and methods of making and using thereof - Google Patents

Abstract

Particulate compositions containing an active agent in combination with a bile salt or a polymer of a bile salt are described herein. The active agent may be the bile salt or polymer thereof. In one embodiment, the active agent is encapsulated in, coated onto, or incorporated into a matrix forming a polymeric microparticle or nanoparticle. The bile salt can be coated onto the surface of the particle or incorporated into a coating which is coated onto the surface of the particle. In another example, polymeric microparticles having active agent encapsulated therein can be dispersed in a bile salt emulsion. Alternatively, the bile salt can be incorporated into the polymeric microparticle or nanoparticle, for example, dispersed throughout the polymeric microparticle or nanoparticle or encapsulated in the core, where active agent(s) is in the core, the polymeric matrix, the coating, or a combination thereof. Active agent can be encapsulated in the core and/or can be dispersed throughout the microparticle. In another embodiment, the active agent is encapsulated in a microparticle, coating, layer, core, emulsion or dispersion formed of a polymer of a bile salt, such as polydeoxycholic acid. Suitable active agents include therapeutic, diagnostic, and/or prophylactic agents. The compositions are formulated for oral administration or administration to a mucosal (nasal, pulmonary, rectal, vaginal, buccal, sublingual).

Description

BILE SALT COLLOIDS AND METHODS OF MAKING

AND USING THEREOF FIELD OF THE INVENTION

The formulations and methods of making and using thereof described herein are in the field of drug delivery, particularly oral drug delivery. CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S.S.N. 60/994,079 entitled "Oral Bioavailability Enhancement of Agents with Bile Salts", filed on September 17, 2007. The disclosures in the application listed above are herein incorporated by reference.

GOVERNMENT SUPPORT

The Federal Government has certain rights in the invention disclosed herein by virtue of Grant No. NIH NRT: CTS-0609326 from the National Institute of Health to Tarek M. Fahmy. BACKGROUND OF THE INVENTION

Oral delivery is the preferred route of drug administration due to high patient comfort and compliance, low administrative costs, and low risk of contamination/infection. However, orally administered active agents face the dual challenge of surviving, in active form, the harsh, degradative conditions of the gastrointestinal environment and crossing the intestinal epithelium in amounts sufficient to provide a therapeutic effect. The low mucosal permeability (particularly for large, hydrophilic compounds) and lack of stability in the GI tract (particularly for peptides) of many active agents results in poor bioavailability following oral administration. Research on improved oral delivery techniques has recently focused on colloidal carriers. Microemulsion carrier systems, such as poly(lactic co- glycolic acid) (PLGA) nanoparticles, are an attractive oral delivery method for a number of reasons including: (1) the encapsulated active agent can be protected from degradative enzymes and acidic environments; (2) the gastrointestinal epithelium is not prematurely exposed to active drug, reducing off-target effects; (3) they are more stable than alternative carriers, such as liposomes, and can release drug in a controlled, predictable manner; (4) their submicron size is appropriate for transcytosis and epithelial transport; and (5) a wide variety of biomaterials and surface modifications enables significant control over chemical properties and biological behavior. However, it has been shown that active agents delivered in oral nanoparticulate formulations can provide observable physiological effects, there has been considerable controversy regarding the mechanism and extent to which particles are absorbed by intestinal mucosa.

Oral delivery effectiveness is influenced by a variety of factors, including particulate size and zeta potential (which is the electrical potential that exists at the shear plane of a particle, which is some small distance from the surface), the nature of the polymer, surface modifications, the presence of nutrients, and the stability and absorptive capacity of the drug itself.

Although successful systems have been explored for particular active agents, no single oral formulation has succeeded in delivering a wide range of poorly absorbable compounds. There exists a need for formulations for enhanced delivery of poorly soluble drugs.

Therefore, it is an object of the invention to provide formulations for the enhanced delivery of poorly soluble and/or absorbable active agents. SUMMARY OF THE INVENTION Particulate compositions containing an active agent in combination with a bile salt or a polymer of a bile salt are described herein. The active agent may be the bile salt or polymer thereof. In one embodiment, the active agent is encapsulated in, coated onto, or incorporated into a maxtrix forming a polymeric microparticle or nanoparticle. The bile salt can be coated onto the surface of the particle or incorporated into a coating which is coated onto the surface of the particle. In another example, polymeric microparticles having active agent encapsulated therein can be dispersed in a bile salt emulsion. Alternatively, the bile salt can be incorporated into the polymeric microparticle or nanoparticle, for example, dispersed throughout the polymeric microparticle or nanoparticle or encapsulated in the core, where active agent(s) is in the core, the polymeric matrix, the coating, or a combination thereof. Active agent can be encapsulated in the core and/or can De dispersed throughout the microparticle. In another embodiment, the active agent is encapsulated in a microparticle, coating, layer, core, emulsion or dispersion formed of a polymer of a bile salt, such as polydeoxycholic acid. Suitable active agents include therapeutic, diagnostic, and/or prophylactic agents. The compositions are formulated for oral administration or administration to a mucosal (nasal, pulmonary, rectal, vaginal, buccal, sublingual).

The bile salts act to enhance transport of the active agent and/or inhibit degradation of the active agent in adverse conditions, such as the acidic environment of the stomach. In particulate form (alone, as a component of microparticles or as bile salt microparticles), surface protonation and decreased solubility of colloids appears to cause aggregation in the low pH of the stomach, which may reduce the rate of erosion and delay release of the active agent. This would increase the amount of encapsulated material present in the small intestine for absorption and limit exposure of the active agent to degradative conditions. The combination of permeation enhancement and pH-responsiveness addresses two primary challenges facing oral delivery formulations and makes bile salt colloids a potentially ideal vehicle for a delivery system.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a graph showing the relative frequency (%) of particulate diameters (nanometers) for polyiactide-co-glycolide (PLGA) particles prepared from a double emulsion process.

Figure 2 is a schematic showing the encapsulation of an active agent in bile salt particles. The bile salt is dissolved in a solvent, such as methanol. The active agent to be encapsulated is added to the bile salt solution and dissolved. The mixture of bile salt and active agent is added to polyvinyl alcohol ("PVA") and the mixture is centrifuged and lyophilized to form bile salt-PVA particles.

Figures 3A and 3B are graphs showing the encapsulation efficiencies (hatched bars, %) and encapsulation loadings (open bars, ng/mg) of rhodamine (mg/ml) in single and double emulsions. Figure 3A shows the ^ 19/09/2008 , ' hodamine in the organic phase. Figure 3B shows the loading of J " ¹' ^***~\ " ,"⁴

<A i i rhodamine in the aqueous phase.

Figure 4 is a graph showing the percentage of encapsulated rhodamine released (%) versus time (hours) for rhodamine encapsulated in PLGA particles suspended in a deoxycholic acid (DCA) emulsion at pH 2 (closed squares), pH 7 (closed circles), and during the transition from pH 2 to pH 7 (closed triangles).

Figure 5 is a graph showing the percentage of encapsulated rhodamine released (%) versus time (hours) for rhodamine encapsulated in PLGA particles at pH 2 (closed triangles) and pH 7 (open triangles) and rhodamine encapsulated in PLGA particles suspended in a deoxycholic acid emulsion at pH 2 (closed squares) and pH 7 (open squares).

Figure 6 is a schematic showing a possible model for the delayed burst released of rhodamine encapsulated in PLGA particles suspended in a deoxycholic acid emulsion at low pH.

Figure 7 is a graph comparing the serum concentrations (mg/mL) versus time (hours) of rhodamine encapsulated in PLGA particles (hatched bars) and rhodamine encapsulated in PLGA particles suspended in a deoxycholic acid emulsion (open bars).

Figure 8 is a graph comparing the rhodamine distribution (ng/mg organ) after 24 hours for rhodamine encapsulated in PLGA particles (hatched bars) and rhodamine encapsulated in PLGA particles suspended in a deoxycholic acid emulsion (open bars).

Figure 9 A is a graph showing the increased permeability of the monolayer simulating the epithelial lining of the intestine (P_app MO^"6 (cm/sec)) as the concentration of deoxycholic acid was increased (mg/ml deoxycholic acid + PLGA). Figure 9B is a graph showing the cytotoxicity in vitro of deoxycholic acid to the Caco-2 cell line. Cytotoxicity is measured using fluorescence as a function of the concentration of DCA (mg/ml of DCA).

RECTIFIED SHEET (RULE 91) iSA/EP DETAILED DESCRIPTION OF THE INVENTION I. Definitions

As used herein, microparticles generally refers to both microparticles in the range of between 0.5 and 1000 microns and nanoparticles in the range of between 50 nm to less than 0.5, preferably having a diameter that is between 1 and 20 microns or having a diameter that is between 50 and 500 nanometers, respectively. Microparticles and nanoparticles are also referred to separately. Unless otherwise specified, "microparticles" or "particles" encompasses both microparticles and nanoparticles. As used herein, "high density" refers to microparticles having a high density of ligands or coupling agents, which is preferably in the range of 1,000 to 10,000,000, more preferably 10,000-1,000,000 ligands per square micron of microparticle surface area. This can be measured by fluorescence staining of dissolved particles and calibrating this fluorescence to a known amount of free fluorescent molecules in solution.

As used herein, "targeting molecule" is a substance which will direct the microparticle to a receptor site on a selected cell or tissue type, can serve as an attachment molecule, or serve to couple or attach another molecule. As used herein, "direct" refers to causing a molecule to preferentially attach to a selected cell or tissue type. This can be used to direct cellular materials, molecules, or drugs, as discussed below.

As used herein, "improved functionality" is the ability to present target for prolonged periods over the course of controlled release from the particle (weeks). Functionality is improved because target molecule remains associated with particle facilitating continuous function over the duration of controlled release.

As used herein, "surface modified matrices" or "surface modified particles" present targets that facilitate attachment of cells, molecules or target specific macromolecules or particles. II. Compositions

Particulate compositions containing an active agent in combination with a bile salt or a polymer of a bile salt are described herein. In one embodiment, the active agent is encapsulated in, coated onto, or incorporated into a matrix forming a polymeric microparticle or nanoparticle. The bile salt can be coated onto the surface of the particle or incorporated into a coating which is coated onto the surface of the particle. In another example, polymeric microparticles having active agent encapsulated therein can be dispersed in a bile salt emulsion. Alternatively, the bile salt can be incorporated into the polymeric microparticle or nanoparticle, for example, dispersed throughout the polymeric microparticle or nanoparticle or encapsulated in the core, where active agent(s) is in the core, the polymeric matrix, the coating, or a combination thereof. Active agent can be encapsulated in the core and/or can be dispersed throughout the microparticle. In one embodiment, the active agent is encapsulated in a microparticle formed of a bile salt or a polymer of a bile salt, such as polydeoxycholic acid. In another embodiment, the active agent is encapsulated in a microparticle, coating, layer, core, emulsion or dispersion formed of a polymer of a bile salt, such as polydeoxycholic acid. Suitable active agents include therapeutic, diagnostic, and/or prophylactic agents. The compositions are formulated for oral administration. A. Bile Salts Bile salts constitute a large family of molecules, composed of a steroid structure with four rings, a five or eight carbon side-chain terminating in a carboxylic acid, and the presence and orientation of different numbers of hydroxyl groups. The four rings are labeled from left to right (as commonly drawn) A, B, C, and D, with the D-ring being smaller by one carbon than the other three. The hydroxyl groups can be in one of two positions: either up (or out) termed beta (often drawn by convention as a solid line), or down, termed alpha (seen as a dashed line in drawings). All bile acids have a hydroxyl group at the 3 position, which was derived from the parent molecule, cholesterol. In cholesterol, the 4 steroid rings are flat and the position of the 3-hydroxyl is beta. In many species, the initial step in the formation of a bile acid is the addition of a 7-alpha hydroxyl group. Subsequently, in the conversion from cholesterol to a bile acid, the junction between the first two steroid rings (A and B) is altered, making the molecule bent, and in this process, the 3-hydroxyl is converted to the alpha orientation. Thus, the default simplest bile acid (of 24 carbons) has two hydroxyl groups at positions 3-alpha and 7-alpha. The chemical name for this compound is 3- alpha,7-alpha-dihydroxy-5-beta-cholan-24-oic acid, or as it is commonly known, chenodeoxycholic acid.

Other suitable bile acids include, but are not limited to, cholic acid, deoxycholic acid, ursodeoxycholic acid, glycocholic acid, taurocholic acid, glycodeoxycholic acid, taurodeoxycholic acid, lithocholic acid, taurolitholic acid.taurochenodeoxycholic acid, tauroursodeoxycholic acid, glycolithocholic acid, glycochenodeoxycholic acid, and taurine conjugates of 3-alpha-7-alpha- 12-alpha-22-xi-tetrahydroxy-5-beta-cholestan-26-oic acid (tetrahydroxystero-cholanic acid) and 3-alpha-12 alpha-22 xi-trihydroxy-5- beta-cholestan-26-oic acid. The structures of deoxycholic acid and ursodeoxycholic acid are shown below.

Deoxycholic Acid: R1 = OH, R2 = H Ursodeoxycholic: R1 = H₁ R2 = OH

Conjugated bile salts are synthesized in hepatocytes, and secreted into the bile canaliculus via specialized transporter systems. The canalicular excretion of bile salts constitutes the rate limiting step in bile formation and the first step in the enterohepatic circulation pathway. They are stored in the bile duct and gall bladder, after which they are released into the duodenum, where they help to improve the solubility and expand the surface of digested fats. Subsequently, they are passively and selectively reabsorbed in the intestinal lumen, primarily via the apical sodium dependent bile salt transporter.

Bile salt oral absorption strategies have employed the conjugation of active drugs to bile salts for drug targeting to bile salt transporters. For example, deoxycholic acid conjugated has been conjugated to heparin, as well as the alkylating cytostatic drug chlorambucil. Furthermore, deoxycholic acid co-administered with PLGA nanoparticles was shown to increase the oral bioavailability of rhodamine in PLGA by as much as 50%. Bile salts have not previously been associated with a carrier for the active agent, on a scale allowing mediation of uptake via the bile salt transporters.

Bile salts also have permeation enhancement properties independent of receptor mediated targeting. Investigations in rat epithelium have shown significant increased apical to basolateral transport of small drug molecules across rat jejunum and ileum and model epithelial cell monolayers in the presence of sodium deoxycholate. Increased absorption of hydrophilic (paracellular preferred) and hydrophobic (transcellular preferred) drugs and markers implicated both transcellular and paracellular routes of absorption, suggesting bile salts can function as penetration enhancer for a wide class of drugs. Bile salt membrane alterations, the primary mechanism in the transcellular route, are hydrophobicity dependant and are primarily displayed by deoxycholic acid, although paracellular tight junctions are disrupted by both DCA and UDCA.

Furthermore, bile salts have pH-dependant solubilites that can be implemented in oral absorption mechanisms. pKa values for DCA and

UDCA are 4.8 and 5.2 at physiological temperature, respectively, meaning that the majority of the bile salt will be protonated in the acidic stomach, but unprotonated in the small intestine (see the illustration below).

Soluble in H2O Insoluble in H2O (aggregate)

As a result, the solubility of both glycine-conjugated and unconjugated bile salts in water rises exponentially with increasing pH. In particulate form, surface protonation and decreased solubility of colloids could cause aggregation in the low pH of the stomach, reducing the rate of erosion and delaying release of drug. This would increase the amount of encapsulated material present in the small intestine for absorption and limit exposure of drug to degradative conditions. The combination of permeation enhancement and pH-responsiveness addresses two primary challenges facing oral delivery formulations and makes bile salt colloids a potentially ideal vehicle for a delivery system.

The bile salts can be polymerized to form polymers which can be used to prepare microparticles or nanoparticles. The structure of polydeoxycholic acid is shown below:

7-α dehydroxylated polymers of several bile salts, including DCA, are found in the lower gut and feces of both humans and hamsters after liver metabolism. Recently, several methods have been developed to synthesize bile acid polymers.

Room temperature polymerization of three naturally occurring bile acids, cholic, lithocholic and deoxycholic, can be carried out using a mixture of diisopropyl carbodiimide (DIPC), and a 1 : 1 salt of dimethyl amino pyridine and p-toluenesulfonic acid (DMAP/PTSA) in mild reaction conditions and without significant cross-linking. Carboiimide activiation leads to preferential esterification at carbon 3 and linear polymeric chains.

The release and degradation properties of polymeric colloid emulsion systems vary with the viscosity, composition, and length of polymer employed in fabrication. Fabrication of polymeric deoxycholic (Figure AA) and ursodeoxycholic acid (pDCA and PUDCA, respectively) colloidal emulsion is likely to involve a formulation similar to the monomeric colloid. The release rates of formulations utilizing different average length polymeric chains are likely to be significantly different. B. Polymers

Non-biodegradable or biodegradable polymers may be used to form the matrix, core, layers or coatings of the microparticles or nanoparticles, or a part of a dispersion or emulsion including the bile salts. In the preferred embodiment, the microparticles are formed of a biodegradable polymer. Non-biodegradable polymers may be used for oral administration. In general, synthetic polymers are preferred, although natural polymers may be used and have equivalent or even better properties, especially some of the natural biopolymers which degrade by hydrolysis, such as some of the polyhydroxyalkanoates. Representative synthetic polymers are: poly(hydroxy acids) such as poly(lactic acid), poly(glycolic acid), and poly(lactic acid-co-glycolic acid), poly(lactide), poly(glycolide), poly(lactide-co-glycolide), polyanhydrides, polyorthoesters, polyamides, polycarbonates, polyalkylenes such as polyethylene and polypropylene, polyalkylene glycols such as poly(ethylene glycol), polyalkylene oxides such as poly(ethylene oxide), polyalkylene terepthalates such as poly(ethylene terephthalate), polyvinyl alcohols, polyvinyl ethers, polyvinyl esters, polyvinyl halides such as polyvinyl chloride), polyvinylpyrrolidone, polysiloxanes, polyvinyl alcohols), polyvinyl acetate), polystyrene, polyurethanes and co-polymers thereof, derivativized celluloses such as alkyl cellulose, hydroxyalkyl celluloses, cellulose ethers, cellulose esters, nitro celluloses, methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, hydroxy-propyl methyl cellulose, hydroxybutyl methyl cellulose, cellulose acetate, cellulose propionate, cellulose acetate butyrate, cellulose acetate phthalate, carboxylethyl cellulose, cellulose triacetate, and cellulose sulfate sodium salt (jointly referred to herein as "synthetic celluloses"), polymers of acrylic acid, methacrylic acid or copolymers or derivatives thereof including esters, poly(methyl methacrylate), poly(ethyl methacrylate), poly(butylmethacrylate), poly(isobutyl methacrylate), poly(hexylmethacrylate), poly(isodecyl methacrylate), poly(lauryl methacrylate), poly(phenyl methacrylate), poly(methyl acrylate), poly(isopropyl acrylate), poly(isobutyl acrylate), and poly(octadecyl acrylate) (jointly referred to herein as "polyacrylic acids"), poly(butyric acid), poly(valeric acid), and poly(lactide-co-caprolactone), copolymers and blends thereof. As used herein, "derivatives" include polymers having substitutions, additions of chemical groups and other modifications routinely made by those skilled in the art.

Examples of preferred biodegradable polymers include polymers of hydroxy acids such as lactic acid and glycolic acid, and copolymers with PEG, polyanhydrides, poly(ortho)esters, polyurethanes, poly(butyric acid), poly(valeric acid), poly(lactide-co-caprolactone), blends and copolymers thereof.

Examples of preferred natural polymers include proteins such as albumin, collagen, gelatin and prolamines, for example, zein, and polysaccharides such as alginate, cellulose derivatives and polyhydroxyalkanoates, for example, polyhydroxybutyrate. The in vivo stability of the microparticles can be adjusted during the production by using polymers such as poly(lactide-co-glycolide) copolymerized with polyethylene glycol (PEG). If PEG is exposed on the external surface, it may increase the time these materials circulate due to the hydrophilicity of PEG.

Examples of preferred non-biodegradable polymers include ethylene vinyl acetate, poly(meth)acrylic acid, polyamides, copolymers and mixtures thereof.

In a preferred embodiment, PLGA is used as the biodegradable polymer.

The microparticles are designed to release molecules to be encapsulated or attached over a period of days to weeks. Factors that affect the duration of release include pH of the surrounding medium (higher rate of release at pH 5 and below due to acid catalyzed hydrolysis of PLGA) and polymer composition. Aliphatic polyesters differ in hydrophobicity and that in turn affects the degradation rate. Specifically the hydrophobic poly (lactic acid) (PLA), more hydrophilic poly (glycolic acid) PGA and their copolymers, poly (lactide-co-glycolide) (PLGA) have various release rates. The degradation rate of these polymers, and often the corresponding drug release rate, can vary from days (PGA) to months (PLA) and is easily manipulated by varying the ratio of PLA to PGA. C. Molecules to be Encapsulated There are two principle groups of molecules to be encapsulated or attached to the polymer, either directly or via a coupling molecule: targeting molecules, attachment molecules and therapeutic, nutritional, diagnostic or prophylactic agents. These can be coupled using standard techniques or using the methods described herein. The targeting molecule or therapeutic molecule to be delivered can be coupled directly to the polymer or to a material such as a fatty acid which is incorporated into the polymer.

Agents to be delivered include therapeutic, nutritional, diagnostic, and prophylactic compounds. Proteins, peptides, carbohydrates, polysaccharides, nucleic acid molecules, and organic molecules, as well as diagnostic agents, can be delivered. The preferred materials to be incorporated are drugs and imaging agents. Therapeutic agents include antibiotics, antivirals (especially protease inhibitors alone or in combination with nucleosides for treatment of HIV or Hepatitis B or C), anti-parasites (helminths, protozoans), anti-cancer (referred to herein as "chemotherapeutics", including cytotoxic drugs such as doxorubicin, cyclosporine, mitomycin C, cisplatin and carboplatin, BCNU, 5FU, methotrexate, adriaraycin, camptothecin, and taxol), antibodies and bioactive fragments thereof (including humanized, single chain, and chimeric antibodies), antigen and vaccine formulations, peptide drugs, antiinflammatories, nutraceuticals such as vitamins, and oligonucleotide drugs (including DNA, RNAs, antisense, aptamers, ribozymes, external guide sequences for ribonuclease P, and triplex forming agents).

Specific classes and examples of drugs include antiinflammatories (steroids, immune modulators, nsaids, cox-2 inhibitors), anti rejection medications for transplants such as liver translplant (cyclosporine (Neoral®, Sandimmune®, prednisone (Novo Prednisone®, Apo Prednisone®), azathioprine (Imuran®), tacrolimus or FK506 (Prograf®), mycophenolate mofetil (CellCept®), sirolimus (Rapamune®), ATGAM and Thymoglobulin; antineoplastics and other agents such as: Aldesleukin, Alemtuzumab, Altretamine, Amsacrine, Anastrozole, Arsenic trioxide, Asparaginase, Azacitidine, Bexarotene, Bicalutamide, Bleomycin, Busulfan, Capecitabine, Carboplatin, Carmustine, Chlorambucil, Cisplatin , Cladribine, Colchicine, Cyclophosphamide, Cytarabine, Cyclosporin, Dacarbazine, Dactinomycin , Daunorubicin, Denileukin, Docetaxel, Doxorubicin, Dutasteride, Epirubicin, Estramustine phosphate sodium, Etoposide, Exemestane, Floxuridine, Fludarabine, Fluorouracil, Flutamide, Fulvestrant, Gemcitabine, Gemtuzumab ozogamicin, Goserelin, Hydroxyurea, Ibritumomab tiuxetan, Idarubicin, Ifosfamide, Imatinib mesylate, Interferon alfa-2a, Interferon alfa- 2b, Interferon alfa-nl, Interferon alfa-n3, interferon, Irinotecan HCl, Leflunomide, Letrozole, Leuprolide, Lomustine, Mechlorethamine, Megestrol, Melphalan, Mercaptopurine, Methotrexate, Mitomycin, Mitotane, Mitoxantrone HCl, Mycophenolate mofetil, Nilutamide, Oxaliplatin, Paclitaxel, Pegaspargase, Pentostatin, Perphosphamide, Pipobroman, Piritrexim, Plicamycin, Prednimustine, Procarbazine, Raltitrexed , Ribavirin, Streptozocin, Tacrolimus, Tamoxifen, Temozolomide, Teniposide, Testolactone, Thalidomide, Thioguanine, Thiotepa, Topotecan, Toremifene, Tositumomab, Trifluridine, Trimetrexate glucuronate, Triptorelin, Uracil mustard, Valganciclovir, Valrubicin, Vidarabine, Vinblastine sulfate, Vincristine sulfate, Vindesine, Vinorelbine tartrate, Zidovudine, avastin, herceptin, monoclonal humanized antibodies, antibody fragments, icons, microRNA; antibody therapeutics: siRNA for gene therapy gene therapy, antivirals, antiretrovirals, antiinfectives, antibacterials, lipidoids, cholesterol- siRNA hybrids, antirejection medications, protease inhibitors, polymerase inhibitors, vaccines, radiosensitizing agents, and hormonal therapy. Hepatitis drugs include interferon, Adefovir/Hepsera, lamivudine, and emtricitabine.

In addition, combinations or individual use of infusional 5- fluorouracil, leucovorin, and oxaliplatin (FOLFOX); 5-fluorouracil (5-FU) or Capecitabine (Xeloda®); Leucovorin (LV, Folinic Acid); Oxaliplatin (Eloxatin®); Combination of infusional 5-fluorouracil, leucovorin, and oxaliplatin (FOLFOX) with bevacizumab or infusional 5-fluorouracil, leucovorin, and irinotecan (FOLFIRI) with bevacizumab; 5-fluorouracil (5- FU) or Capecitabine; Leucovorin (LV, Folinic Acid), Irinotecan (Camptosar®), Oxaliplatin (Eloxatin®), Bevacizumab (Avastin®),

Cetuximab (Erbitux®), Panitumumab (Vectibix), Bortezomib (Velcade®), Oblimersen (Genasense®, G3139), Gefitinib, Erlotinib (Tarceva®), Topotecan (Hycamtin®).

Exemplary diagnostic materials include paramagnetic molecules, fluorescent compounds, magnetic molecules, and radionuclides.

Alternatively, the biodegradable polymers may encapsulate cellular materials, such as for example, cellular materials to be delivered to antigen presenting cells as described below to induce immunological responses. Peptide, protein, and DNA based vaccines may be used to induce immunity to various diseases or conditions. For example, sexually transmitted diseases and unwanted pregnancy are world-wide problems affecting the health and welfare of women. Effective vaccines to induce specific immunity within the female genital tract could greatly reduce the risk of STDs, while vaccines that provoke anti-sperm antibodies would function as immunocontraceptives. Extensive studies have demonstrated that vaccination at a distal site-orally, nasally, or rectally, for example-can induce mucosal immunity within the female genital tract. Of these options, oral administration has gained the most interest because of its potential for patient compliance, easy administration and suitability for widespread use. Oral vaccination with proteins is possible, but is usually inefficient or requires very high doses. Oral vaccination with DNA, while potentially effective at lower doses, has been ineffective in most cases because 'naked DNA' is susceptible to both the stomach acidity and digestive enzymes in the gastrointestinal tract. In addition to disease-causing cells, disease effector agents include microbes such as bacteria, fungi, yeast, viruses which express or encode disease- associated antigens, and prions, D. Targeting or Attachment Molecules

Targeting molecules can be proteins, peptides, nucleic acid molecules, saccharides or polysaccharides that bind to a receptor or other molecule on the surface of a targeted cell. The degree of specificity can be modulated through the selection of the targeting molecule. For example, antibodies are very specific. These can be polyclonal, monoclonal, fragments, recombinant, or single chain, many of which are commercially available or readily obtained using standard techniques. Table 1 is a list of ligand-targeted nanoparticulate systems providing examples of useful ligands and their targets. Examples of molecules targeting extracellular matrix ("ECM") include glycosaminoglycan ("GAG") and collagen. In one embodiment, the external surface of polymer microparticles may be modified to enhance the ability of the microparticles to interact with selected cells or tissue. The method of example 1 wherein a fatty acid conjugate is inserted into the microparticle is preferred. However, in another embodiment, the outer surface of a polymer microparticle having a carboxy terminus may be linked to PAMPs that have a free amine terminus. The PAMP targets Toll- like Receptors (TLRs) on the surface of the cells or tissue, or signals the cells or tissue internally, thereby potentially increasing uptake. PAMPs conjugated to the particle surface or co-encapsulated may include: unmethylated CpG DNA (bacterial), double-stranded RNA (viral), lipopolysacharride (bacterial), peptidoglycan (bacterial), lipoarabinomannin (bacterial), zymosan (yeast), mycoplasmal lipoproteins such as MALP -2 (bacterial), flagellin (bacterial) poly(inosinic-cytidylic) acid (bacterial), lipoteichoic acid (bacterial) or imidazoquinolines (synthetic).

Table 1: Selected list of ligand-targeted nanoparticulate systems evaluated for in vitro or in vivo therapeutics delivery

Lieand Drug System Target Cells Evaluation

Nucleic acids Aptamers^a PLA Prostate In vitro Epithelial cells

ECM Proteins

Integra^ Raf genes Liposomes Melanoma cells In vivo

RGD peptides^ siRNA PEI tumor vasculature In vivo Fibrinogen^ radioisotopes Albumin tumor vasculature In vivo Lipids

MP Lipid A^e PLGA Dendritic cells In vitro

Carbohydrates

Galactose^ retinoic acid PLA Hepatocytes In vitro Hyaluronic Doxorubicin Liposomes CD44+ melanoma cells In vitro acidS

PeptidomimeticsⁿVarious mPEG/PLGA Brain cells Various Antibodies to:

HER2 receptor¹ gelatin/HAS HER2 cells In vitro HER2 receptor⁾ Doxorubicin Liposomes HER2 cells In vivo

CD 19^ Doxorubicin Liposomes B cell lymphoma In vivo

Vitamins

Folate¹ Doxorubicin Liposomes Leukemia cells In vivo a. Park, J. W. et al. Clin Cancer Res 8, 1172-1 181 (2002). b. Hood, J.D. et al. Science 296, 2404-2407 (2002). c. Schiffelers, R.M. et al. Nucleic Acids Res 32, el49 (2004). d. Hallahan, D. et al. Cancer Cell 3, 63-74 (2003). e. Elamanchili, et al. Vaccine 22, 2406-2412 (2004). f. Cho, CS. et al. J Control Release 11, 7-15 (2001). g. Eliaz, R.E. & Szoka, F.C., Jr. Cancer Res 61, 2592-2601 (2001). h. Olivier, J.C. Neurorx 2, 108-1 19 (2005). i. Wartlick, H. et al. JDrug Target 12, 461-471 (2004). j. Park, J.W. et al. Clin Cancer Res 8, 1 172-1 181 (2002) k. Lopes de Menezes, et al. Cancer Res 58, 3320-3330 (1998).

1. Pan, X.Q. et al. Blood 100, 594-602 (2002). In another embodiment, the outer surface of the microparticle may be treated using a mannose amine, thereby mannosylating the outer surface of the microparticle. This treatment may cause the microparticle to bind to the target cell or tissue at a mannose receptor on the antigen presenting cell surface. Alternatively, surface conjugation with an immunoglobulin molecule containing an Fc portion (targeting Fc receptor), heat shock protein moiety (HSP receptor), phosphatidylserine (scavenger receptors), and lipopolysaccharide (LPS) are additional receptor targets on cells or tissue. Lectins that can be covalently attached to microparticles to render them target specific to the mucin and mucosal cell layer include lectins isolated from Abrus precatroius, Agaricus bisporus, Anguilla anguilla, Arachis hypogaea, Pandeiraea simplicifolia, Bauhinia purpurea, Caragan arobrescens, Cicer arietinum, Codium fragile, Datura stramonium, Dolichos biflorus, Eryth^ήna corallodendron, Erythrina cristagalli, Euonymus europaeus, Glycine max, Helix aspersa, Helix pomatia, Lathyrus odoratus, Lens culinaris, Limulus polyphemus, Lysopersicon esculentum, Madura pomifera, Momordica charantia, Mycoplasma gallisepticum, Naja mocambique, as well as the lectins Concanavalin A, Succinyl-Concanavalin A, Triticum vulgaris, Ulex europaeus I, II and HI, Sambucus nigra, Maackia amurensis, Limaxfluvus, Homarus ameήcanus, Cancer antennarius, and Lotus tetragonolobus.

The attachment of any positively charged ligand, such as polyethyleneimine or polylysine, to any microparticle may improve bioadhesion due to the electrostatic attraction of the cationic groups coating the beads to the net negative charge of the mucus. The mucopolysaccharides and mucoproteins of the mucin layer, especially the sialic acid residues, are responsible for the negative charge coating. Any ligand with a high binding affinity for mucin could also be covalently linked to most microparticles with the appropriate chemistry, such as the fatty acid conjugates of example 1 or CDI, and be expected to influence the binding of microparticles to the gut. For example, polyclonal antibodies raised against components of mucin or else intact mucin, when covalently coupled to microparticles, would provide for increased bioadhesion. Similarly, antibodies directed against specific cell surface receptors exposed on the lumenal surface of the intestinal tract would increase the residence time of beads, when coupled to microparticles using the appropriate chemistry. The ligand affinity need not be based only on electrostatic charge, but other useful physical parameters such as solubility in mucin or else specific affinity to carbohydrate groups.

The covalent attachment of any of the natural components of mucin in either pure or partially purified form to the microparticles would decrease the surface tension of the bead-gut interface and increase the solubility of the bead in the mucin layer. The list of useful ligands would include but not be limited to the following: sialic acid, neuraminic acid, n-acetyl-neuraminic acid, n-glycolylneuraminic acid, 4-acetyl-n-acetylneuraminic acid, diacetyl- n-acetylneuraminic acid, glucuronic acid, iduronic acid, galactose, glucose, mannose, fucose, any of the partially purified fractions prepared by chemical treatment of naturally occurring mucin, e.g., mucoproteins, mucopolysaccharides and mucopolysaccharide-protein complexes, and antibodies immunoreactive against proteins or sugar structure on the mucosal surface.

The attachment of polyamino acids containing extra pendant carboxylic acid side groups, e.g., polyaspartic acid and polyglutamic acid, should also provide a useful means of increasing bioadhesiveness. Using polyamino acids in the 15,000 to 50,000 kDa molecular weight range would yield chains of 120 to 425 amino acid residues attached to the surface of the microparticles. The polyamino chains would increase bioadhesion by means of chain entanglement in mucin strands as well as by increased carboxylic charge.

The microparticles can be futher modified by encapsulation within liposomes.

E. Pharmaceutical Compositions The compositions can be foπnulated for oral administration. As would be appreciated by one of skill in this art, the one or more excipieints and/or carriers may be chosen based on the dosage form to be adminstered, the active agents being delivered, etc. As used herein, the term "pharmaceutically acceptable carrier" means a non-toxic, diluent, encapsulating material or formulation auxiliary of any type. Remington 's Pharmaceutical Sciences Ed. by Gennaro, Mack Publishing, Easton, Pa., 1995 discloses various carriers used in formulating pharmaceutical compositions and known techniques for the preparation thereof.

Suitable excipients include surfactants, emulsifiers, emulsion stabilizers, anti-oxidants, emollients, humectants, chelating agents, suspending agents, thickening agents, occlusive agents, preservatives, stabilizing agents, pH modifying agents, solubilizing agents, solvents, flavoring agents, colorants, fragrances, and other excipients. As used herein, "excipient" does not include any bile salt or polymer thereof.

Emulsifiers Suitable emulsifiers include, but are not limited to, straight chain or branched fatty acids, polyoxyethylene sorbitan fatty acid esters, sorbitan fatty acid esters, propylene glycol stearate, glyceryl stearate, polyethylene glycol, fatty alcohols, polymeric ethylene oxide-propylene oxide block copolymers, and combinations thereof.

Surfactants Suitable surfactants include, but are not limited to, anionic surfactants, non-ionic surfactants, cationic surfactants, and amphoteric surfactants. Examples of anionic surfactants include, but are not limited to, ammonium lauryl sulfate, sodium lauryl sulfate, ammonium laureth sulfate, sodium laureth sulfate, alkyl glyceryl ether sulfonate, triethylamine lauryl sulfate, triethylamine laureth sulfate, triethanolamine lauryl sulfate, triethanolamine laureth sulfate, monoethanolamine lauryl sulfate, monoethanolamine laureth sulfate, diethanolamine lauryl sulfate, diethanolamine laureth sulfate, lauric monoglyceride sodium sulfate, potassium lauryl sulfate, potassium laureth sulfate, sodium lauryl sarcosinate, sodium lauroyl sarcosinate, lauryl sarcosine, cocoyl sarcosine, ammonium cocoyl sulfate, ammonium laur oyl sulfate, sodium cocoyl sulfate, sodium lauroyl sulfate, potassium cocoyl sulfate, potassium lauryl sulfate, triethanolamine lauryl sulfate, triethanolamine lauryl sulfate, monoethanolamine cocoyl sulfate, monoethanolamine lauryl sulfate, sodium tridecyl benzene sulfonate, sodium dodecyl benzene sulfonate, sodium and ammonium salts of coconut alkyl triethylene glycol ether sulfate; tallow alkyl triethylene glycol ether sulfate, tallow alkyl hexaoxyethylene sulfate, disodium N-octadecylsulfosuccinnate, disodium lauryl sulfosuccinate, diammonium lauryl sulfosuccinate, tetrasodium N-(l,2-dicarboxyethyl)-N- octadecylsulf- osuccinnate, diamyl ester of sodium sulfosuccinic acid, dihexyl ester of sodium sulfosuccinic acid,-dioctyl esters of sodium sulfosuccinic acid, docusate sodium, and combinations thereof.

Examples of nonionic surfactants include, but are not limited to, polyoxyethylene fatty acid esters, sorbitan esters, cetyl octanoate, cocamide DEA, cocamide MEA, cocamido propyl dimethyl amine oxide, coconut fatty acid diethanol amide, coconut fatty acid monoethanol amide, diglyceryl diisostearate, diglyceryl monoisostearate, diglyceryl monolaurate, diglyceryl monooleate, ethylene glycol distearate, ethylene glycol monostearate, ethoxylated castor oil, glyce ryl monoisostearate, glyceryl monolaurate, glyceryl monomyristate, glyceryl monooleate, glyceryl monostearate, glyceryl tricaprylate/caprate, glyceryl triisostearate, glyceryl trioleate, glycol distearate, glycol monostearate, isooctyl stearate, lauramide DEA, lauric acid diethanol amide, lauric acid monoethanol amide, lauric/myristic acid diethanol amide, lauryl dimethyl amine oxide, lauryl/ myristyl amide DEA, lauryl/myristyl dimethyl amine oxide, methyl gluceth, methyl glucose sesquistearate, oleamide DEA, PEG-distearate, polyoxyethylene butyl ether, polyoxyethylene cetyl ether, polyoxyethylene lauryl amine, polyoxyethylene lauryl ester, polyoxyethylene lauryl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene octyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene oleyl amine, polyoxyethyelen oleyl cetyl ether, polyoxyethylene oleyl ester, polyoxyethylene oleyl ether, polyoxyethylene stearyl amine, polyoxyethylene stearyl ester, polyoxyethylene stearyl ether, polyoxyethylene tallow amine, polyoxyethylene tridecyl ether, propylene glycol monostearate, sorbitan monolaurate, sorbitan monooleate, sorbitan monopalmitate, sorbitan monostearate, sorbitan sesquioleate, sorbitan trioleate, stearamide DEA, stearic acid diethanol amide, stearic acid monoethanol amide, laureth-4, and combinations thereof.

Examples of amphoteric surfactants include, but are not limited to, sodium N-dodecyl-y-alanine, sodium N-lauryl-y-iminodipropionate, myristoamphoacetate, lauryl betaine, lauryl sulfobetaine, sodium 3-dodecyl- aminopropionate, sodium 3-dodecylaminopropane sulfonate, sodium lauroamphoacetate, cocodimethyl carboxymethyl betaine, cocoamidopropyl betaine, cocobetaine, lauryl amidopropyl betaine, oleyl betaine, lauryl dimethyl carboxymethyl betaine, lauryl dimethyl alphacarboxyethyl betaine, cetyl dimethyl carboxymethyl betaine, lauryl bis-(2-hydroxyethyl) carboxymethyl betaine, stearyl bis-(2-hydroxypropyl) carboxymethyl betaine, oleyl dimethyl gamma-carboxypropyl betaine, lauryl bis-(2- hydroxypropyl)alpha-carboxyeth- yl betaine, oleamidopropyl betaine, coco dimethyl sulfopropyl betaine, stearyl dimethyl sulfopropyl betaine, lauryl dimethyl sulfoethyl betaine, lauryl bis-(2-hydroxyethyl) sulfopropyl betaine, and combinations thereof.

Examples of cationic surfactants include, but are not limited to, behenyl trimethyl ammonium chloride, bis(acyloxyethyl) hydroxyethyl methyl ammonium methosulfate, cetrimonium bromide, cetrimonium chloride, cetyl trimethyl ammonium chloride, cocamido propylamine oxide, distearyl dimethyl ammonium chloride, ditallowdimonium chloride, guar hydroxypropyltrimonium chloride, lauralkonium chloride, lauryl dimethylamine oxide, lauryl dimethylbenzyl ammonium chloride, lauryl polyoxyethylene dimethylamine oxide, lauryl trimethyl ammonium chloride, lautrimonium chloride, methyl- 1 -oleyl amide ethyl-2-oleyl imidazolinium methyl sulfate, picolin benzyl ammonium chloride, polyquaternium, stearalkonium chloride, sterayl dimethylbenzyl ammonium chloride, stearyl trimethyl ammonium chloride, trimethylglycine, and combinations thereof. Hydrophobic surfactants such as fatty acids and cholesterol may be added during manufacturing of the microparticles to improve the resulting distribution of hydrophobic active agent in hydrophobic polymeric microparticles. Examples of fatty acids include butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, caprylic acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachic acid, isocrotonic acid, undecylenic acid, oleic acid, elaidic acid, sorbic acid, linoleic acid, linolenic acid and arachidonic acid.

Hydrophilic surfactants such as amphiphilic solvents like TWEEN^® 20 and polyvinyl alcohol improve distribution of hydrophilic active agents in the polymers. Amphiphilic surfactants are preferred if the active agent is hydrophilic and the polymer is hydrophobic.

Suspending Agents

Suitable suspending agents include, but are not limited to, alginic acid, bentonite, carbomer, carboxymethylcellulose and salts thereof, colloidal oatmeal, hydroxyethylcellulose, hydroxypropylcellulose, microcrystalline cellulose, colloidal silicon dioxide, dextrin, gelatin, guar gum, xanthan gum, kaolin, magnesium aluminum silicate, maltitol, triglycerides, methylcellulose, polyoxyethylene fatty acid esters, polyvinylpyrrolidone, propylene glycol alginate, sodium alginate, sorbitan fatty acid esters, tragacanth, and combinations thereof. Antioxidants

Suitable antioxidants include, but are not limited to, butylated hydroxytoluene, alpha tocopherol, ascorbic acid, fumaric acid, malic acid, butylated hydroxyanisole, propyl gallate, sodium ascorbate, sodium metabisulfϊte, ascorbyl palmitate, ascorbyl acetate, ascorbyl phosphate, Vitamin A, folic acid, flavons or flavonoids, histidine, glycine, tyrosine, tryptophan, carotenoids, carotenes, alpha-Carotene, beta-Carotene, uric acid, pharmaceutically acceptable salts thereof, derivatives thereof, and combinations thereof.

Chelating Agents Suitable chelating agents include, but are not limited to, EDTA, disodium edetate, trans-l,2-diaminocyclohexane-N,N,N',N'-tetraaceticacid monohydrate, N,N-bis(2-hydroxyethyl)glycine, l,3-diamino-2- hydroxypropane-N,N,N',N'-te- traacetic acid, 1,3-diaminopropane- N,N,N',N'-tetraacetic acid, ethylenediamine-N,N'-diacetic acid, ethylenediamine-N.N'-dipropionic acid, ethylenediamine-N,N'- bis(methylenephosphonic acid), N-(2-hydroxyethyl)ethylenediamine- N,N',N'-triacetic acid, ethylenediamine-N,N,N',N'- tetrakis(methylenephosponic acid), O,O'-bis(2-aminoethyl)ethyleneglycol- N,N,N',N'-tetraacetic acid, N,N-bis(2-hydroxybenzyl)ethylenediamine-N,N- diacetic acid, 1 ,6-hexamethylenediamine-N,N,N',N'-tetraacetic acid, N-(2- hydroxyethyl)iminodiacetic acid, iminodiacetic acid, 1 ,2-diaminopropane- N,N,N',N'-tetraacetic acid, nitrilotriacetic acid, nitrilotripropionic acid, nitrilotris(methylenephosphoric acid), 7,19,30-trioxa-l,4,10,13,16,22,27,33- octaazabicyclo[l 1,11,11] pentatriacontane hexahydrobroraide, triethylenetetramine-N,N,N^l,N",N'",N'"-hexaacetic acid, and combinations thereof. Humectants

Suitable humectants include, but are not limited to, glycerin, butylene glycol, propylene glycol, sorbitol, triacetin, and combinations thereof. pH Modifying Agents The compositions described herein may further contain sufficient amounts of at least one pH modifier to ensure that the composition has a final pH of about 3 to about 11. Suitable pH modifying agents include, but are not limited to, sodium hydroxide, citric acid, hydrochloric acid, acetic acid, phosphoric acid, succinic acid, sodium hydroxide, potassium hydroxide, ammonium hydroxide, magnesium oxide, calcium carbonate, magnesium carbonate, magnesium aluminum silicates, malic acid, potassium citrate, sodium citrate, sodium phosphate, lactic acid, gluconic acid, tartaric acid, 1,2,3,4-butane tetracarboxylic acid, fumaric acid, diethanolamine, monoethanolamine, sodium carbonate, sodium bicarbonate, triethanolamine, and combinations thereof. Preservatives

Preservatives can be used to prevent the growth of fungi and other microorganisms. Suitable preservatives include, but are not limited to, benzoic acid, butylparaben, ethyl paraben, methyl paraben, propylparaben, sodium benzoate, sodium propionate, benzalkonium chloride, benzethonium chloride, benzyl alcohol, cetypyridinium chloride, chlorobutanol, phenol, phenylethyl alcohol, thimerosal, and combinations thereof. III. Methods of Making

The compositions described can be prepared by a variety of methods. For example, the active agent to be delivered can be encapsulated in a polymeric microparticles using one of techniques described above. The polymeric microparticles can then be coated with a bile salt, coated with a coating containing a bile salt, or suspended in a bile salt emulsion using techniques well known in the art. Alternatively, the bile salt can be encapsulated with the active agent to be delivered using the techniques described above.

A. Formation of Microparticles and Nanoparticles. There are many methods that can be used to form microparticles or nanoparticles.

Solvent Evaporation.

In this method the polymer is dissolved in a volatile organic solvent, such as methylene chloride. The drug (either soluble or dispersed as fine particles) is added to the solution, and the mixture is suspended in an aqueous solution that contains a surface active agent such as poly(vinyl alcohol). The resulting emulsion is stirred until most of the organic solvent evaporated, leaving solid microparticles. The resulting microparticles are washed with water and dried overnight in a lyophilizer. Microparticles with different sizes (0.5-1000 microns) and morphologies can be obtained by this method. This method is useful for relatively stable polymers like polyesters and polystyrene.

However, labile polymers, such as polyanhydrides, may degrade during the fabrication process due to the presence of water. For these polymers, the following two methods, which are performed in completely anhydrous organic solvents, are more useful. Interfacial polycondensation

Interfacial polycondensation is used to microencapsulate a core material in the following manner. One monomer and the core material are dissolved in a solvent. A second monomer is dissolved in a second solvent (typically aqueous) which is immiscible with the first. An emulsion is formed by suspending the first solution through stirring in the second solution. Once the emulsion is stabilized, an initiator is added to the aqueous phase causing interfacial polymerization at the interface of each droplet of emulsion. Solvent Evaporation Microencapsulation

In solvent evaporation microencapsulation, the polymer is typically dissolved in a water immiscible organic solvent and the material to be encapsulated is added to the polymer solution as a suspension or solution in an organic solvent. An emulsion is formed by adding this suspension or solution to a beaker of vigorously stirring water (often containing a surface active agent, for example, polyethylene glycol or polyvinyl alcohol, to stabilize the emulsion). The organic solvent is evaporated while continuing to stir. Evaporation results in precipitation of the polymer, forming solid microcapsules containing core material. The solvent evaporation process can be used to entrap a liquid core material in a polymer such as PLA, PLA/PGA copolymer, or PLA/PCL copolymer microcapsules. The polymer or copolymer is dissolved in a miscible mixture of solvent and nonsolvent, at a nonsolvent concentration which is immediately below the concentration which would produce phase separation (i.e., cloud point). The liquid core material is added to the solution while agitating to form an emulsion and disperse the material as droplets. Solvent and nonsolvent are vaporized, with the solvent being vaporized at a faster rate, causing the polymer or copolymer to phase separate and migrate towards the surface of the core material droplets. This phase-separated solution is then transferred into an agitated volume of nonsolvent, causing any remaining dissolved polymer or copolymer to precipitate and extracting any residual solvent from the formed membrane. The result is a microcapsule composed of polymer or copolymer shell with a core of liquid material.

Solvent evaporation microencapsulation can result in the stabilization of insoluble active agent particles in a polymeric solution for a period of time ranging from 0.5 hours to several months. Stabilizing an insoluble pigment and polymer within the dispersed phase (typically a volatile organic solvent) can be useful for most methods of microencapsulation that are dependent on a dispersed phase, including film casting, solvent evaporation, solvent removal, spray drying, phase inversion, and many others.

The stabilization of insoluble active agent particles within the polymeric solution could be critical during scale-up. By stabilizing suspended active agent particles within the dispersed phase, the particles can remain homogeneously dispersed throughout the polymeric solution as well as the resulting polymer matrix that forms during the process of microencapsulation..

Solvent evaporation microencapsulation (SEM) have several advantages. SEM allows for the determination of the best polymer-solvent- insoluble particle mixture that will aid in the formation of a homogeneous suspension that can be used to encapsulate the particles. SEM stabilizes the insoluble particles or pigments within the polymeric solution, which will help during scale-up because one will be able to let suspensions of insoluble particles or pigments sit for long periods of time, making the process less time-dependent and less labor intensive. SEM allows for the creation of microparticles or nanoparticles that have a more optimized release of the encapsulated material.

Hot Melt Microencapsulation.

In this method, the polymer is first melted and then mixed with the solid particles. The mixture is suspended in a non-miscible solvent (like silicon oil), and, with continuous stirring, heated to 5DC above the melting point of the polymer. Once the emulsion is stabilized, it is cooled until the polymer particles solidify. The resulting microparticles are washed by decantation with petroleum ether to give a free-flowing powder. Microparticles with sizes between 0.5 to 1000 microns are obtained with this method. The external surfaces of spheres prepared with this technique are usually smooth and dense. This procedure is used to prepare microparticles made of polyesters and polyanhydrides. However, this method is limited to polymers with molecular weights between 1,000-50,000.

Solvent Removal Microencapsulation In solvent removal microencapsulation, the polymer is typically dissolved in an oil miscible organic solvent and the material to be encapsulated is added to the polymer solution as a suspension or solution in organic solvent. Surface active agents can be added to improve the dispersion of the material to be encapsulated. An emulsion is formed by adding this suspension or solution to vigorously stirring oil, in which the oil is a nonsolvent for the polymer and the polymer/solvent solution is immiscible in the oil. The organic solvent is removed by diffusion into the oil phase while continuing to stir. Solvent removal results in precipitation of the polymer, forming solid microcapsules containing core material.

Phase Separation Microencapsulation In phase separation microencapsulation, the material to be encapsulated is dispersed in a polymer solution with stirring. While continually stirring to uniformly suspend the material, a nonsolvent for the polymer is slowly added to the solution to decrease the polymer's solubility. Depending on the solubility of the polymer in the solvent and nonsolvent, the polymer either precipitates or phase separates into a polymer rich and a polymer poor phase. Under proper conditions, the polymer in the polymer rich phase will migrate to the interface with the continuous phase, encapsulating the core material in a droplet with an outer polymer shell.

Spontaneous Einulsification Spontaneous emulsification involves solidifying emulsified liquid polymer droplets by changing temperature, evaporating solvent, or adding chemical cross-linking agents. The physical and chemical properties of the encapsulant, and the material to be encapsulated, dictates the suitable methods of encapsulation. Factors such as hydrophobicity, molecular weight, chemical stability, and thermal stability affect encapsulation.

Coacervation Encapsulation procedures for various substances using coacervation techniques have been described in the prior art, for example, in GB-B-929 406; GB-B-929401; U.S. Patent nos. 3,266,987; 4,794,000 and 4,460,563. Coacervation is a process involving separation of colloidal solutions into two or more immiscible liquid layers (Ref. Dowben, R. General Physiology, Harper & Row, New York, 1969, pp. 142-143.). Through the process of coacervation compositions comprised of two or more phases and known as coacervates may be produced. The ingredients that comprise the two phase coacervate system are present in both phases; however, the colloid rich phase has a greater concentration of the components than the colloid poor phase. Solvent Removal. This technique is primarily designed for polyanhydrides. In this method, the drug is dispersed or dissolved in a solution of the selected polymer in a volatile organic solvent like methylene chloride. This mixture is suspended by stirring in an organic oil (such as silicon oil) to form an emulsion. Unlike solvent evaporation, this method can be used to make microparticles from polymers with high melting points and different molecular weights. Microparticles that range between 1-300 microns can be obtained by this procedure. The external morphology of spheres produced with this technique is highly dependent on the type of polymer used. Spray-Drying In this method, the polymer is dissolved in organic solvent. A known amount of the active drug is suspended (insoluble drugs) or co- dissolved (soluble drugs) in the polymer solution. The solution or the dispersion is then spray-dried. Typical process parameters for a mini-spray drier (Buchi) are as follows: polymer concentration = 0.04 g/mL, inlet temperature = -24DC, outlet temperature = 13-15 DC, aspirator setting = 15, pump setting = 10 mL/minute, spray flow = 600 Nl/hr, and nozzle diameter = 0.5 mm. Microparticles ranging between 1-10 microns are obtained with a morphology which depends on the type of polymer used.

Hydrogel Microparticles Microparticles made of gel-type polymers, such as alginate, are produced through traditional ionic gelation techniques. The polymers are first dissolved in an aqueous solution, mixed with barium sulfate or some bioactive agent, and then extruded through a microdroplet forming device, which in some instances employs a flow of nitrogen gas to break off the droplet. A slowly stirred (approximately 100-170 RPM) ionic hardening bath is positioned below the extruding device to catch the forming microdroplets. The microparticles are left to incubate in the bath for twenty to thirty minutes in order to allow sufficient time for gelation to occur. Microparticle particle size is controlled by using various size extruders or varying either the nitrogen gas or polymer solution flow rates. Chitosan microparticles can be prepared by dissolving the polymer in acidic solution and crosslinking it with tripolyphosphate. Carboxymethyl cellulose (CMC) microparticles can be prepared by dissolving the polymer in acid solution and precipitating the microparticle with lead ions. In the case of negatively charged polymers (e.g., alginate, CMC), positively charged ligands (e.g., polylysine, polyethyleneimine) of different molecular weights can be ionically attached.

B. Methods for Attachment or Binding to Surface Functionality refers to conjugation of a ligand to the surface of the particle via a functional chemical group (carboxylic acids, aldehydes, amines, sulfhydryls and hydroxyls) present on the surface of the particle and present on the ligand to be attached. Functionality may be introduced into the particles in two ways. The first is during the preparation of the microparticles, for example during the emulsion preparation of microparticles by incorporation of stabilizers with functional chemical groups. Example 1 demonstrates this type of process whereby functional amphiphilic molecules are inserted into the particles during emulsion preparation. A second is post-particle preparation, by direct crosslinking particles and ligands with homo- or heterobifunctional crosslinkers. This second procedure may use a suitable chemistry and a class of crosslinkers (CDI, EDAC, glutaraldehydes, etc. as discussed in more detail below) or any other crosslinker that couples ligands to the particle surface via chemical modification of the particle surface after prepartion. This second class also includes a process whereby amphiphilic molecules such as fatty acids, lipids or functional stabilizers may be passively adsorbed and adhered to the particle surface, thereby introducing functional end groups for tethering to ligands.

In one embodiment, the surface is modified to insert amphiphilic polymers or surfactants that match the polymer phase HLB or hydrophilic- lipophilic balance, as demonstrated in the following example. HLBs range from 1 to 15. Surfactants with a low HLB are more lipid loving and thus tend to make a water in oil emulsion while those with a high HLB are more hydrophilic and tend to make an oil in water emulsion. Fatty acids and lipids have a low HLB below 10. After conjugation with target group (such as hydrophilic avidin), HLB increases above 10. This conjugate is used in emulsion preparation. Any amphiphilic polymer with an HLB in the range 1-10, more preferably between 1 and 6, most preferably between 1 and up to 5, can be used. This includes all lipids, fatty acids and detergents.

One useful protocol involves the "activation" of hydroxyl groups on polymer chains with the agent, carbonyldiimidazole (CDI) in aprotic solvents such as DMSO, acetone, or THF. CDI forms an imidazolyl carbamate complex with the hydroxyl group which may be displaced by binding the free amino group of a ligand such as a protein. The reaction is an N- nucleophilic substitution and results in a stable N-alkylcarbamate linkage of the ligand to the polymer. The "coupling" of the ligand to the "activated" polymer matrix is maximal in the pH range of 9-10 and normally requires at least 24 hrs. The resulting ligand-polymer complex is stable and resists hydrolysis for extended periods of time. Another coupling method involves the use of l-ethyl-3-(3- dimethylaminopropyl) carbodiimide (EDAC) or "water-soluble CDI" in conjunction with N-hydroxylsulfosuccinimide (sulfo NHS) to couple the exposed carboxylic groups of polymers to the free amino groups of ligands in a totally aqueous environment at the physiological pH of 7.0. Briefly, EDAC and sulfo-NHS form an activated ester with the carboxylic acid groups of the polymer which react with the amine end of a ligand to form a peptide bond. The resulting peptide bond is resistant to hydrolysis. The use of sulfo-NHS in the reaction increases the efficiency of the EDAC coupling by a factor of ten-fold and provides for exceptionally gentle conditions that ensure the viability of the ligand-polymer complex.

By using either of these protocols it is possible to "activate" almost all polymers containing either hydroxyl or carboxyl groups in a suitable solvent system that will not dissolve the polymer matrix. A useful coupling procedure for attaching ligands with free hydroxyl and carboxyl groups to polymers involves the use of the cross-linking agent, divinylsulfone. This method would be useful for attaching sugars or other hydroxylic compounds with bioadhesive properties to hydroxylic matrices. Briefly, the activation involves the reaction of divinylsulfone to the hydroxyl groups of the polymer, forming the vinylsulfonyl ethyl ether of the polymer. The vinyl groups will couple to alcohols, phenols and even amines. Activation and coupling take place at pH 11. The linkage is stable in the pH range from 1-8 and is suitable for transit through the intestine.

Any suitable coupling method known to those skilled in the art for the coupling of ligands and polymers with double bonds, including the use of UV crosslinking, may be used for attachment of molecules to the polymer.

Coupling is preferably by covalent binding but it may also be indirect, for example, through a linker bound to the polymer or through an interaction between two molecules such as strepavidin and biotin. It may also be by electrostatic attraction by dip-coating.

The molecules to be delivered can also be encapsulated into the polymer using double emulsion solvent evaporation techniques, such as that described by Luo et al, Controlled DNA delivery system, Phar. Res., 16: 1300-1308 (1999).

C. Methods for making emulsions and dispersions

An emulsion is the mixture of two immiscible substances. A discrete or discontinuous phase (e.g. oil) is dispersed in continuous phase (e.g., water). Examples of emulsions include an oil-in-water (O/W) emulsion and an water-in-oil (W/O) emulsion. Emulsions are unstable and thus do not form spontaneously. Energy input through shaking, stirring, homogenization, or spray processing are generally needed to form an emulsion. Emulsions are part of a more general class of two-phase systems of matter called colloids. Although the terms colloid and emulsion are sometimes used interchangeably, emulsion tends to imply that both the dispersed and the continuous phase are liquid. Emulsifiers, such as surfactants, may be used to promote dispersion of the discrete phase in the continuous phase and thus stabilize the emulsion.

A colloid dispersion generally refers to a solid discontinuous phase dispersed in a liquid continuous phase. Natural colloids are those that are self-dispersing upon addition of the solid to the liquid dispersing medium. Artifical colloids require additional means for dispersion of the solid in the continuous phase. Such means include pulverization of coarse particles to colloidal size by a colloid mill or a micropulvirizer or colloidal size particles may be formed by chemical reaction under controlled conditions. IV. Methods of Use

The submicron size of nanoparticulates offers distinct advantages over larger systems: first, the small size enables them to extravasate through blood vessels and tissue. This is especially important for tumor vessels, which are often dilated and fenestrated with an average pore size less than a micron, compared to normal tissue. Second, solid nanoparticles made from biodegradable polymers and encapsulating drug are ideal for sustained intracellular drug delivery, especially for drugs whose targets are cytoplasmic. The dosage loading varies depending on the nature of encapsulant. Up to 80% of initial total amount of agent to be incorporated can be encapsulated in the microparticles.

The microparticles are useful in drug delivery (as used herein "drug" includes therapeutic, nutritional, diagnostic and prophylactic agents), whether administered to a mucosal surface (vaginal, rectal, buccal, sublingual, nasal, or pulmonary), or encapsulated for oral delivery. The dosage is determined using standard techniques based on the drug to be delivered and the method and form of administration. The microparticles may be administered as a dry powder, as a suspension, in a hydrogel, organogel, or liposome, in capsules, tablets, troches, or other standard pharmaceutical excipient.

The bile salts can act to enhance transport of the active agent and/or inhibit degradation of the active agent in adverse conditions, such as the acidic environment of the stomach. In particulate form (alone, as a component of microparticles or as bile salt microparticles), surface protonation and decreased solubility of colloids appears to cause aggregation in the low pH of the stomach, which may reduce the rate of erosion and delay release of the active agent. This would increase the amount of encapsulated material present in the small intestine for absorption and limit exposure of the active agent to degradative conditions. The combination of permeation enhancement and pH-responsiveness addresses two primary challenges facing oral delivery formulations and makes bile salt colloids a potentially ideal vehicle for a delivery system.

This system can be utilized for drug targeting to the liver and kidney increasing oral bioavailability.

The formulations are particularly useful for treatment of Hepatitis A, B, C, D E and other hepatitis causing paradigms; Hepatic cancers such as hepatocellular carcinoma; metastases to the liver such as metastatic colon, rectal, colorectal, ovarian, lung, prostate, pancreatic, gastric and other cancers; parasitic infections such as those in the liver or other organs such as the lungs and brain; transplantation of organs such as the liver; hypercholesterolemia, hyperlipidemia and other such disease which often involve enterohepatic organs. As used herein, hepatitis is disease caused by: Hepatitis A to E Herpes simplex, Cytomegalovirus, Epstein-Barr, yellow fever virus, adenoviruses. Additional disorders include Non viral infection such as: toxoplasma, Leptospira, Q fever, rocky mountain spotted fever; disease caused by alcohol or toxins, including toxins such as: Amanita toxin in mushrooms, Carbon tetrachloride, asafetida; and drugs such as Paracetamol, amoxycillin, anti tuberculosis medicines, minocycline and many others; circulatory insufficiency; pregnancy; auto immune conditions e.g. SLE; and metabolic diseases e.g. Wilson's disease. Ursodeoxycholic acid-methotrexate combination therapy in a colloidal system for primary biliary cirrhosis is an example of an application of the method and system described herein.

Primary biliary cirrhosis (PBC) is a chronic cholestatic liver disease of unknown cause. The median age of PBC sufferers is 50, with women being primarily affected by a 9: 1 margin. High incidence rates among those with predisposition to autoimmunity and patterns of inheritance suggest a genetic origin, although the presence of tobacco and other environmental factors has been associated with the disease. Best current evidence suggests PBC is an immune-mediate condition, with abnormal suppressor T-cell activity and antibody formation against pyruvate dehydrogenase reported pre-symptomatically. Progressive bile-duct injury from portal inflammation often results in progressive fibrosis and eventual cirrhosis, leading to altered bile acid metabolism. Common symptoms include fatigue and pruritus, excessive subcutaneous deposition of cholesterol, and jaundice. Ursodeoxycholic acid (UDCA) is the only currently FDA-approved treatment for PBC and other choleostatic disorders. It is administered orally in its unconjugated form, absorbed passively in the small intestine, and metabolized in the liver. UDCA stimulates biliary secretion of bile acids by transcriptional and post-transcriptional mechanisms in hepatocytes. In addition, a wide range of immunosuppressors have been investigated to counteract the autoimmune aspects of the disorder. Methotrexate is an immunosuppressive folic-acid antagonist widely indicated in low and high dose regimens for a range of pathologies, most prominently rheumatoid arthritis and PBC.

Clinical trials of ursodeoxycholic acid and ursodeoxycholic acid- methotrexate combination therapy in PBC have yielded conflicting results, although most have advocated continued treatment, particularly in light of UDCA being the only FDA-approved PBC treatment. Combination therapy with methotrexate has not been shown successful in clinical trials, although recent biochemical studies have re-emphasized the potential of combination therapy in PBC, suggesting the tremendous variety in patient response to treatment has obscured the significance of these clinical trials. Long-term medium-dose UDCA-methotrexate was shown to improve histological and symptomatic response in PBC patients who are incomplete biochemical responders to ursodeoxycholic acid therapy, suggesting potential for further investigation of oral ursodeoxycholic acid-methotrexate formulations. Furthermore, although methotrexate can be administered orally with acceptable bioavailability and toxicity, several aspects of its oral pharmacokinetics are problematic: 1) bioavailability is incomplete and highly variable among the patient population, with decreased absorption among the elderly and those with impaired hepatic and renal function, a key demographic for PBC, 2) there is a dose-dependant gastrointestinal toxicity mediated by altered folate metabolism (adverse effects from low-dose methotrexate cause as many as 35% of patients to discontinue use) absorption is rapid and requires frequent administrations of drug with high spikes in that limit administration levels with toxicity. A bile-salt particulate methotrexate delivery system should address all three of these concerns via permeation enhancement, sequestering drug from GI tract, and delayed, controlled release of drug, respectively. Ursodeoxycholic acid in PBC could play a double role as both colloidal carrier and therapeutic, as controlled erosion of particulate would increase local concentrations of UDCA while simultaneously releasing encapsulated drug. The present invention will be further understood by reference to the following non-limiting examples.

Examples Materials PLGA with an inherent viscosity of 0.59 dL/g, lot D02022 was supplied from Birmingham Polymers Inc. Polyvinyl alcohol (Mw average 30-70 kDa), deoxycholic acid (99% purity), ursodeoxycholic acid (99% purity), pepsin, bovine serum albumin and trypsin were all obtained from Sigma Chemical Co. Methylene chloride was of chromatography grade and supplied by Fischer Chemicals. All other reagents were of reagent grade and used as received. Example 1. Preparation of PLGA Particles

Polylactide-co-glycolide (PLGA) nanoparticles were prepared using a modified water-oil-water (W/O/W) emulsion process. In the first emulsion, 100 uL of rhodamine B at 10 mg/ml in phosphate buffered saline was added dropwise to a vortexing PLGA solution in methylene chloride (200 mg of PLGA in 4 ml of methylene chloride). The emulsion was sonicated for thirty seconds (three times at 10 seconds each time) on ice. The W/O emulsion was added to 8 mL of 5% polyvinyl alcohol (PVA) with vortexing. The mixture was sonicated for thirty seconds (three times at 10 seconds each time) on ice. After sonication, the mixture was added to 200 mL of 0.3% PVA and spun for 3 hours at room temperature. The resultant emulsion was purified by centrifugation at 13,000 rpm for 10 minutes at 4⁰C and washed three times with deionized (DI) water. The particles were freeze-dried, lyophilized, and stored at 2O⁰C.

Samples were characterized by scanning electron microscopy (SEM). The particles were fixed on an aluminum stub using 2-sided carbon tape and coated with gold in an argon atmosphere using a sputter current of 4OmA (Dynavac Mini Coater, Dynavac, USA). SEM analysis was carried out with a Philips XL30 SEM using a LaB electron gun with an accelerating voltage of 5-10 kV. Diameters were determined using the ImageJ particle sizing software from the NIH. The relative frequencies of the particulate diameters for PLGA particles prepared by the double emulsion techniques are shown in Figure 1. Example 2. Preparation of deoxycholic and ursodeoxycholic acid microparticles Deoxycholic and Ursodeoxycholic acid particles were prepared as single (0/W) or double (W/O/W) emulsions, depending on the nature of the compound to be encapsulated. The compound to be encapsulated and 1 OO mg of bile salt were dissolved in 1 mL of methanol. In a double emulsion, 100 μL of the compound to be encapsulated were added dropwise while vortexing. The bile salt suspension was added dropwise to 1 mL of 1% PVA while vortexing. To vary size, 0.5 or 2 mL of 2% and 0.5% PVA, respectively, were also used as the aqueous phases. The resultant emulsion was then purified by centrifugation at 12,00Og for 10 minutes and washed with DI water. The particles were freeze-dried, lyophilized, and stored at 2O⁰C. Stable, uniform nanoparticles were obtained using these methods. A schematic showing the methods for preparing these formulations is shown in Figure 2.

Samples were characterized by scanning electron microscopy (SEM). Samples were sputter-coated with gold under vacuum in an argon atmosphere using a sputter current of 4OmA (Dynavac Mini Coater,

Dynavac, USA). SEM analysis was carried out with a Philips XL30 SEM using a LaB electron gun with an accelerating voltage of 5-10 kV. Diameters were determined using the ImageJ particle sizing software from the NIH. Total encapsulant content was measured by dissolving the particles in ethanol overnight and measuring the amount of material released from the particles.

Particulate mean diameter may be varied within the appropriate absorptive size range by modifying formulation volume. Volume restriction likely induces aggregation of nucleation sites, leading to increasing particulate size as total emulsion volume was decreased. A constant quantity of deoxycholic acid was dissolved in methanol and added to different PVA volumes to produce a variety of particle sizes. The change in diameter as a function of formulation volume is shown in the table below.

In a manner similar to PLGA particulates in a deoxycholic acid emulsion, deoxycholic acid-based particulates demonstrate strong pH dependant release properties for the model active agent rhodamine. These differences in release profiles as a function of pH are shown in Figure 4. Rhodamine release from particulate at physiological temperature is pH- dependant. Protonation at pH 2 (pKa deoxycholic acid = 5.5) appears to induce increased hydrophobicity and aggregation of particulates as demonstrated by SEM and light microscopy. Rhodamine release is thus delayed at low pH likely as a result of decreased fluid exposure to particulates in the interior of the aggregate (dark-colored squares). Full release occurs over an 8 hour time period. Exposure of particles to physiological pH following 4 hours at pH 2, as would occur in the GI tract, induces more rapid degradation with full release after 2 hours at pH 7 (dark- colored triangles). pH dependant release behavior indicates potential as a protective agent in the acidic stomach environment.

Particulates can be fabricated as spontaneous single or double emulsions, depending on the nature of the encapsulant. A double emulsion allows for the presentation of hydrophilic encapsulants in an aqueous phase (and insulates peptides and nucleotides from harsh organics), while restricting the volume in which the encapsulant can be present (usually approximately 100 uL per 1 mL of organic phase). Dissolving less hydrophilic encapsulants in the organic phase allows a larger volume to be used for encapsulation, as long as they can be exposed to harsh hydrophobic conditions. As shown in Figures 3a and 3b, deoxycholic acid is able to encapsulate rhodamine in both the aqueous and organic phase. Encapsulation in organic phase reduces encapsulation efficiencies while allowing loading as high as 40 ng drug/ mg bile salt. With an aqueous loading, encapsulation efficiencies near 100% were achieved, and in all cases appeared higher than their organic counterparts. Thus, organic encapsulation increases loading at the expense of encapsulation. In both cases, as expected, presenting a larger quantity of drug initially increases loading while decreasing efficiency. Example 3. In vitro release of rhodamine from PLGA nanoparticles suspended in a deoxycholic acid emulsion

Release of encapsulated rhodamine was carried out in sodium phosphate buffer titrated with hydrochloric acid to pH 2 and 7 at 37⁰C. Samples were placed in dialysis tubing (exclusion size 10,000 MW) at 20 mg/ml in buffer dialyzed against 50 mL of buffer. At appropriate time points, 100 uL of buffer was removed and rhodamine concentration was read by fluorescence (excitation 540; emission 620). The fraction of protein released was calculated by dividing the amount of rhodamine at the indicated time points by the total content of both model active agent in 10 mg of the same stock of particles. Total rhodamine content was measured by dissolving 10 mg of particles in 1 N dimethyl sulfoxide overnight.

The percentage of rhodamine released from PLGA particles (dark and light triangles) and from PLGA particles suspended in a deoxycholic acid emulsion (dark and light squares) at pH 2 and pH 7 is shown in Figure 5. The PLGA particles alone showed accelerated release kinetic at pH 2 (dark- colored triangles) as compared to pH 7 (light-colored triangles). Suspension of the PLGA particles in a deoxycholic acid emulsion formulation delayed accelerated release at low pH (dark-colored squares) while not affected release at high pH (light-colored squares).

A proposed model to explain this observation is shown in Figure 6. Without being bound by any one theory, it is believed that at low pH, the PLGA particles aggregate together and are surrounded by the deoxycholic acid emulsion.

Example 4. In vivo release of rhodamine from PLGA nanoparticles suspended in a deoxycholic acid emulsion To test whether deoxycholic acid improves the dynamics of absorption of PLGA, mice were fed PLGA nanoparticles loaded with Rhodamine B with and without a DCA emulsion, and the concentrations of rhodamine in serum and tissues were measured over time. C3H mice were obtained from Charles River Laboratories (Wilmington, MA) and maintained under pathogen free conditions and routinely monitored by Yale Animal Resource Center. Mice of 10-12 weeks were fasted overnight and fed 300μl of solution using a blunted end oral gavage needle containing 25 μg of rhodamine either alone or in particles PLGA particles delivered without deoxycholate resulted in a kinetic profile similar to that observed with free rhodamine (data not shown); peak rhodamine levels were measured 4 hrs after PLGA administration and levels of the dye were observed up to 12 hrs. At indicated timepoints, mice were sacrificed and blood was collected by cardiac puncture. Blood was allowed to clot at 37 ⁰C for 15 minutes, centrifuged at 3000 G for 15 minutes, and serum was collected for analysis. Heart, lung, liver, spleen, and kidney were collected and homogenized in water. Extraction was performed in a solution of 8 : 1 : 1 70% methanol, 10% Triton-X 100, and sample at -20 ⁰C overnight. The samples were then centrifuged at 13,000 RPM and the fluorescence of the supernatant was measured (Excitation: 540 nm; Emission: 620 nm). The area-under- curve (AUC) was estimated by the trapezoidal method applied to the fluorescence intensity vs. time curve. The PLGA particles in the DCA emulsion produced extended serum levels after oral administration, with peak levels occurring 4 to 24 hrs and the duration of delivery extending beyond 24 hrs. The results are shown in Figure 7. AUC was calculated using the log-linear trapezoidal rule due to the limit on data points. Increased bioavailability was also observed since the particles with deoxycholic acid yielded an AUC of 9.74 ± 1.34 compared to 5.37 ± .282 without deoxycholic acid or a relative bioavailability of 1.81 (p < 0-01 ). A significantly higher C_max, was seen with the free particles potentially exposing cells to toxic levels as compared to the intermediate levels maintained with the emulsion. Rhodamine concentrations in the liver were significantly higher with deoxycholic acid potentially due to the hepatic portal reabsorption of deoxycholate (Figure 8). Free particles were found to be similar to free rhodamine most likely due to acidcatalyzed degradation of the PLGA in the stomach. Deoxycholic acid/PLGA emulsion showed increased bioavailability with maintenance of rhodamine concentrations at intermediate levels for 24- 48 hrs. Rhodamine B has been shown to be cleared from circulation within hours so the levels observed in the blood can be attributed to additional absorption from the intestine or release from particles. Rhodamine B has also been shown to have several metabolites with different fluorescent emissions, demonstrating that the system delivers significant amounts of unmetabolized dye to the circulation. This increased absorption could be due to several factors. Aggregation of the particles in the stomach could result in delayed transit time, facilitating increased absorption. Disruption of the tight junctions by deoxycholic acid could allow transport of the nanoparticles across the intestinal lining between the eel 1. Alternatively, the dye or particles may have been transported through the cells via the active and passive pathways for deoxycholic acid. In addition, cycling of the dye in the enterohepatic circulation could provide sustained release into the bloodstream.

Example 4. Release characteristics of bovine serum albumin encapsulated in deoxycholic acid particles Initial observations of the degradation behavior with the model protein bovine serum albumin (BSA) encapsulated in deoxycholic acid particulates showed that these formulations were able to resist in vitro simulated digestive conditions (pepsin at pH=2) as demonstrated by gel electrophoresis. Although many bands were visible even for the pure BSA lane (this purity is consistent with literature for the highly sensitive silver staining regiment, which can detect impurities to a nanomolar concentration), a strong BSA-associated band is present in the pure BSA, BSA in particulate, and BSA in particulate in the presence of pepsin and low pH band. This suggests the preservation of BSA structure (no digestion) in the presence of digestive enzymes when encapsulated. The relatively gentle particulate formulation process, which is spontaneous and requires no sonication, should allow for the encapsulation of intact and activated forms of peptides and nucleotides. Example 5. Preparation of polydeoxycholic acid

Deoxycholic acid (0.53 g, 1.35 mmol) and a 1 :1 salt of dimethylaminopyridine (DMAP) and para-toluene sulfonic acid (PTSA) (0.045g, 0.143 mmol) were mixed in a 100 mL, round bottom 3-necked flask under nitrogen. Using a syringe, 15 mL of anydroυs methylene chloride (CH₂Cl₂) was added slowly while stirring at 4O⁰C. N.N'-diisopropyl carbodiimide (DIC, 0.22g, 1.73 mmol) was added and the homogeneous solution was continuously stirred at room temperature for 30 hours. The polymer product was precipitated by pouring the reaction mixture into a solution of 200 mL of dry methanol (CH3OH) while stirring. After centrifugation, 0.45 g (47.3 % yield) of a while solid, poly(deoxycholic acid) was obtained and characterized by proton NMR: (CDC13, d), with peaks at 0.68 (s, 3H) [C18-CH3]; 0.92 (s, 3H) [C19 -CH3]; 0.98 (d, 3H) [C21-CH3]; 0.99-2.4 (multitude of signals); 4.0 (m, IH) [Cl 2-H]; 4.7 (m, IH) [C3-H]. Example 6. Caco-2 studies of intestinal transport and cytotoxicity

Caco-2 cells were seeded at 7 x 1 o4 cells/cm² on 0.4 μm pore transwell filters in Dulbecco's modified eagle media containing 10% fetal bovine serum (FBS), 100 U/mL penicillin, 100 μg/mL streptomycin, and 0.1 mM nonessential amino acids. The cells were grown to confluency and allowed to mature for approximately 30 days at 37⁰C and 5% CO₂. Cell culture media was changed every 2-3 days.

Prior to performing permeability studies, the transepithelial electrical resistance (TEER) was measured using an epithelial voltometer (World Precision Instruments, EVOMX with STX2 electrodes). Confluent cell layers with TEER values greater than 300 ohms x cm² were used for permeability and cytotoxicity studies.

For permeability studies, a solution of 40 mg/mL rhodamine-loaded PLGA nanoparticles was prepared in phenol-free Hank's balanced salt solution (HBSS) containing 25 mM glucose and varying concentrations of deoxycholic acid. The cells were kept incubated at 37⁰C and 5% CO₂. 400 μL of this solution was added to the apical chamber of the transwell filter, and 400 μL of HBSS containing 25 mM glucose was added to the basolateral chamber. Every 30 minutes, 100 μL of the media in the basolateral chamber was sampled and replaced with 100 μL of fresh HBSS containing 25 mM glucose.

Basolateral media samples were obtained for five hours. The amount of rhodamine in the basolateral sampled media was determined by dissolving it with 100 μL of dimethyl sulfoxide overnight in a 37⁰C rotary shaker, and then measuring rhodamine fluorescence (Ex: 540 nm, Em: 620 nm). From these measurements, the cumulative amount of rhodamine transport to the basolateral chamber was determined as a function of time. The rate of cumulative rhodamine transport to the basolateral chamber gave the flux, dC/dt. The permeability (P) was calculated by dividing the flux by the initial concentration of total rhodamine in the apical chamber (Co) and the area of the transwell filter (A).

As seen in Figures 9a and 9b, increased permeability of the monolayer was observed as the concentration of deoxycholic acid was increased. This has been demonstrated for a wide variety of molecules but not for a nanoparticulate system.

Example 7. Evaluation of the cytotoxicity of deoxycholate Cell titer blue assay (PromegaB) was used to measure the cytotoxicity of deoxycholate. After the 5 hour permeability measurements, cells were washed with buffer, then replaced with 200 μL of varying concentrations of deoxycholic acid in the apical chamber. 50 μL of cell titer blue reagent was added to the apical chamber, and allowed to incubate with cells for an additional 90 minutes. Following incubation, 100 μL of media from the apical chamber was read in fluorimeter (Excitation: 560 nm, Emission: 590 nm). The media was diluted until the fluorescence measurement was linear with dilution.

Cytotoxicity, using this assay, was observed at high concentrations An effective but non-toxic range between 1 and 2.5 mg/ml of DCA was demonstrated in these conditions. This suggests that conditions may exist in vivo where DCA enhances permeability with limited damage to the epithelial lining. However, levels of deoxycholic acid must be maintained in a narrow effective range due to its potential toxicity. Deoxychoiic acid has been suggested as a potential tumor promoter and induces apoptosis in cancer cells, suggesting that the chemopreventive ursodeoxycholic acid, which has similar properties to deoxychoiic acid, should potentially be used instead. Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of skill in the art to which the disclosed invention belongs. Publications cited herein and the materials for which they are cited are specifically incorporated by reference. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the following claims.

Claims

We claim:

1. A pharmaceutically acceptable formulation comprising microparticles, nanoparticles, a dispersion or an emulsion comprising bile salts or polymer thereof for delivery of the bile salts or active agents associated therewith.

2. The formulation of claim 1 wherein the microparticles or nanoparticles comprise bile salts as a coating, layer, core, or incorporated into or forming the matrix of the microparticle or nanoparticle.

3. The formulation of claim 1 comprising active agent selected from the group consisting of therapeutic, nutritional, diagnostic and prophylactic agents.

4. The formulation of claim 1 wherein the bile salt or polymer thereof is in a dispersion or emulsion.

5. The formulation of claim 1 further comprising attachment or targeting molecules bound to or incorporated in the microparticles or nanoparticles.

6. The formulation of claim 3 comprising an active agent selected from the group consisting of Therapeutic agents include antibiotics, antivirals, anti-parasites, chemotherapeutics, antibodies and bioactive fragments thereof, antigen and vaccine formulations, peptide drugs, antiinflammatories, oligonucleotide drugs, antiinflammatories, anti rejection medications; antineoplastics, protease inhibitors, polymerase inhibitors, vaccines.

7. The formulation of claim 2 wherein the microparticles or nanoparticles comprise a natural or synthetic polymer.

8. The formulation of claim 1 wherein the bile salt or polymer thereof is the active aent.

9. A method of drug delivery comprising administering to an individual in need thereof an effective amount of the formulation of any of claims 1-8.

10. The method of claim 9 wherein the formulation is administered orally.

11. The method of claim 9 wherein the formulation is administered to a region selected from the group consisting of buccal, nasal, sublingual, pulmonary, rectal, and vaginal.

12. The method of claim 9 wherein the formulation is administered orally for delivery to the hepatic or portal circulation.

13. A method of making a drug delivery formulation comprising formulating the formulation of any of claims 1-8.