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  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K31/00—Medicinal preparations containing organic active ingredients
  • A61K31/21—Esters, e.g. nitroglycerine, selenocyanates
  • A61K31/215—Esters, e.g. nitroglycerine, selenocyanates of carboxylic acids
  • A61K31/216—Esters, e.g. nitroglycerine, selenocyanates of carboxylic acids of acids having aromatic rings, e.g. benactizyne, clofibrate
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K9/00—Medicinal preparations characterised by special physical form
  • A61K9/48—Preparations in capsules, e.g. of gelatin, of chocolate
  • A61K9/50—Microcapsules having a gas, liquid or semi-solid filling; Solid microparticles or pellets surrounded by a distinct coating layer, e.g. coated microspheres, coated drug crystals
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K39/00—Medicinal preparations containing antigens or antibodies
  • A61K39/02—Bacterial antigens
  • A61K39/085—Staphylococcus
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K39/00—Medicinal preparations containing antigens or antibodies
  • A61K39/12—Viral antigens
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K39/00—Medicinal preparations containing antigens or antibodies
  • A61K39/39—Medicinal preparations containing antigens or antibodies characterised by the immunostimulating additives, e.g. chemical adjuvants
• • A—HUMAN NECESSITIES
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  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K9/00—Medicinal preparations characterised by special physical form
  • A61K9/14—Particulate form, e.g. powders, Processes for size reducing of pure drugs or the resulting products, Pure drug nanoparticles
  • A61K9/16—Agglomerates; Granulates; Microbeadlets ; Microspheres; Pellets; Solid products obtained by spray drying, spray freeze drying, spray congealing,(multiple) emulsion solvent evaporation or extraction
  • A61K9/1605—Excipients; Inactive ingredients
  • A61K9/1629—Organic macromolecular compounds
  • A61K9/1635—Organic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds, e.g. polyvinyl pyrrolidone, poly(meth)acrylates
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K9/00—Medicinal preparations characterised by special physical form
  • A61K9/14—Particulate form, e.g. powders, Processes for size reducing of pure drugs or the resulting products, Pure drug nanoparticles
  • A61K9/16—Agglomerates; Granulates; Microbeadlets ; Microspheres; Pellets; Solid products obtained by spray drying, spray freeze drying, spray congealing,(multiple) emulsion solvent evaporation or extraction
  • A61K9/1605—Excipients; Inactive ingredients
  • A61K9/1629—Organic macromolecular compounds
  • A61K9/1641—Organic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds, e.g. polyethylene glycol, poloxamers
  • A61K9/1647—Polyesters, e.g. poly(lactide-co-glycolide)
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K9/00—Medicinal preparations characterised by special physical form
  • A61K9/48—Preparations in capsules, e.g. of gelatin, of chocolate
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P37/00—Drugs for immunological or allergic disorders
  • A61P37/02—Immunomodulators
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P37/00—Drugs for immunological or allergic disorders
  • A61P37/02—Immunomodulators
  • A61P37/04—Immunostimulants
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K39/00—Medicinal preparations containing antigens or antibodies
  • A61K2039/54—Medicinal preparations containing antigens or antibodies characterised by the route of administration
  • A61K2039/541—Mucosal route
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K39/00—Medicinal preparations containing antigens or antibodies
  • A61K2039/545—Medicinal preparations containing antigens or antibodies characterised by the dose, timing or administration schedule
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K39/00—Medicinal preparations containing antigens or antibodies
  • A61K2039/555—Medicinal preparations containing antigens or antibodies characterised by a specific combination antigen/adjuvant
  • A61K2039/55511—Organic adjuvants
  • A61K2039/55555—Liposomes; Vesicles, e.g. nanoparticles; Spheres, e.g. nanospheres; Polymers
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K38/00—Medicinal preparations containing peptides
• • C—CHEMISTRY; METALLURGY
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  • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
  • C12N2770/00—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA ssRNA viruses positive-sense
  • C12N2770/00011—Details
  • C12N2770/24011—Flaviviridae
  • C12N2770/24111—Flavivirus, e.g. yellow fever virus, dengue, JEV
  • C12N2770/24134—Use of virus or viral component as vaccine, e.g. live-attenuated or inactivated virus, VLP, viral protein
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
  • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
  • Y02A50/30—Against vector-borne diseases, e.g. mosquito-borne, fly-borne, tick-borne or waterborne diseases whose impact is exacerbated by climate change
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
  • Y10T428/2982—Particulate matter [e.g., sphere, flake, etc.]
  • Y10T428/2984—Microcapsule with fluid core [includes liposome]
  • Y10T428/2985—Solid-walled microcapsule from synthetic polymer
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
  • Y10T428/2982—Particulate matter [e.g., sphere, flake, etc.]
  • Y10T428/2989—Microcapsule with solid core [includes liposome]

Definitions

• This invention relates to a method and a formulation for orally administering a bioactive agent encapsulated in one or more biocompatible polymer or copolymer excipients, preferably a biodegradable polymer or copolymer, affording microcapsules which due to their proper size and physicalchemical properties results in the microcapsules and contained agent reaching and being effectively taken up by the folliculi lymphatic aggregati, otherwise known as the "Peyer's patches", of the gastrointestinal tract in an animal without loss of effectiveness due to the agent having passed through the gastrointestinal tract.
• the folliculi lymphatic aggregati can be found in the respiratory tract, genitourinary tract, large intestine and other mucosal tissues of the body.
• the above-described tissues are referred to in general as mucosallyassociated lymphoid tissues.
• microencapsulation to protect sensitive bioactive agents from degradation has become well-known.
• a bioactive agent is encapsulated within any of a number of protective wall materials, usually polymeric in nature.
• the agent to be encapsulated can be coated with a single wall of polymeric material (microcapsules), or can be homogeneously dispersed within a polymeric matrix (microspheres).
• microcapsules refers to both microcapsules and microspheres.
• the amount of agent inside the microcapsule can be varied as desired, ranging from either a small amount to as high as 95% or more of the microcapsule composition.
• the diameter of the microcapsule can also be varied as desired, ranging from less than one micrometer to as large as three millimeters or more.
• Peyer's patches are aggregates of lymphoid nodules located in the wall of the small intestine, large intestine and appendix and are an important part of body's defense against the adherence and penetration of infectious agents and other substances foreign to the body.
• Antigens are substances that induce the antibodyproducing and/or cell-mediated immune systems of the body, and include such things as foreign protein or tissue.
• the immunologic response induced by the interaction of an antigen with the immune system may be either positive or negative with respect to the body's ability to mount an antibody or cell-mediated immune response to a subsequent reexposure to the antigen.
• Cell-mediated immune responses include responses such as the killing of foreign cells or tissues, "cell-mediated cytoxicity", and delayed-type hypersensitivity reactions.
• Antibodies belong to a class of proteins called immunoglobulins (Ig), which are produced in response to an antigen, and which combine specifically with the antigen. When an antibody and antigen combine, they form a complex. This complex may aid in the clearance of the antigen from the body, facilitate the killing of living antigens such as infectious agents and foreign tissues or cancers, and neutralize the activity of toxins or enzymes.
• Ig immunoglobulins
• secretory immunoglobulin A secretory immunoglobulin A
• Secretory IgA antibodies prevent the adherence and penetration of infectious agents and other antigens to and through the mucosal tissues of the body.
• IgA precursor B cells which can populate the lamina intestinal regions of the gastrointestinal and upper respiratory tracts and differentiate into mature IgA synthesizing plasma cells. It is these plasma cells which actually secrete the antibody molecules.
• Studies by Heremans and Bazin measuring the development of IgA responses in mice orally immunized with antigen showed that a sequential appearance of antigen-specific IgA plasma cells occurred, first in mesenteric lymph nodes, later in the spleen, and finally in the lamina intestinal tract (Bazin, H., Levi, G . , and Doria, G.
• This circular pattern provides a mucosal immune system by continually transporting sensitized B cells to mucosal sites for responses to gut-encountered environmental antigens and potential pathogens.
• oral immunization is the ability of oral immunization to induce protective antibodies. It is known that the ingestion of antigens by animals results in the appearance of antigen-specific slgA antibodies in bronchial and nasal washings. For example, studies with human volunteers show that oral administration of influenza vaccine is effective at inducing secretory anti-influenza antibodies in nasal secretions.
• This invention relates to a method and formulation for targeting to and then releasing a bioactive agent in the body of an animal by mucosal application, and in particular, oral and intratracheal administration.
• the agent is microencapsulated in a biocompatible polymer or copolymer, preferably a biodegradable polymer or copolymer which is capable of passing through the gastrointestinal tract or existing on a mucosal surface without degradation or with minimal degradation so that the agent reaches and enters the
• biocompatible is defined as a polymeric material which is not toxic to the body, is not carcinogenic, and which should not induce inflammation in body tissues. It is preferred that the microcapsule polymeric excipient be biodegradable in the sense that it should degrade by bodily processes to products readily disposable by the body and should not accumulate in the body.
• the microcapsules are also of a size and physicalchemical composition capable of being effectively and selectively taken up by the Peyer's patches. Therefore, the problems of the agent reaching the Peyer's patch or other mucosally-associated tissue and being taken up are solved.
• Figure 1 represents the plasma IgA responses in mice determined by endpoint titration.
• poly(DL-lactide-co-glycolide) examples include, but are not limited to, poly(glycolide), poly(DL-lactide-coglycolide), copolyoxalates, polycaprolactone, poly (lactide-co-caprolactone), poly (esteramides), polyorthoesters and poly (8-hydroxybutyric acid), and polyanhydrides.
• bioactive ingredients may be used.
• examples of such include, but are not limited to, antigens to vaccinate against viral, bacterial, protozoan, fungal diseases such as influenzae, respiratory syncytial, parainfluenza viruses, Hemophilus influenza, Bordetella pertussis, Neisseria gonorrhoeae, Streptococcus pneumoniae and Plasmodium falciparum or other diseases caused by pathogenic microorganisms or antigens to vaccinate against diseases caused by macroorganisms such as helminthic pathogens or antigens to vaccinate against allergies.
• Additional bioactive agents which may be used included but are not limited to, immunomodulators, nutrients, drugs, peptides, lymphokines and cytokines.
• a polymer solution is prepared by dissolving 4.95 g of polystyrene (Type 685D, Dow
• aqueous poly (vinyl alcohol) (PVA) solution the processing medium, is prepared by dissolving 40 g of PVA (Vinol 2050, Air Products and Chemicals, Allentown, PA) in 360 g of deionized water. After preparing the PVA solution, the solution is saturated by adding 6 g of methylene chloride. Next, the PVA solution is added to a 1-L resin kettle (Ace Glass, Inc., Vineland, NJ) fitted with a truebore stir shaft and a 2.5-in. teflon impeller and stirred at about 380 rpm by a Fisher stedi speed motor.
• PVA poly (vinyl alcohol)
• the polystyrene/coumarin mixture is then added to the resin kettle containing the PVA processing media. This is accomplished by pouring the polystyrene/coumarin mixture through a long-stem 7-mm bore funnel which directs the mixture into the resin kettle. A stable oil-in-water emulsion results and is subsequently stirred for about 30 minutes at ambient pressure to afford oil microdroplets of the appropriate size. Then the resin kettle is closed, and the pressure in the resin kettle is gradually reduced to 520 mm Hg by means of a water aspirator connected to a manometer and a bleed valve. The resin kettle contents are stirred at reduced pressure for about 24 hours to allow all of the methylene chloride to evaporate. After all of the methylene chloride has evaporated, the hardened microcapsules are collected by centrifugation and dried for 72 hours in a vacuum chamber maintained at room temperature.
• TNP-KLH a water-soluble antigen
• poly(DL-lactide-co-glycolide) a biocompatible, biodegradable polyester.
• the procedure used to prepare the microcapsules follows: First, a polymer solution was prepared by dissolving 0.5g of 50:50 poly (DL-lactide-co-glycolide) in 4.0 g of methylene chloride.
• an aqueous solution of TNP-KLH 46 mg TNP-LKH/mL; after dialysis
• aqueous solution of TNP-KLH 46 mg TNP-LKH/mL; after dialysis
• poly (DL-lactide-co-glycolide) solution by vortexing the mixture with a Vortex-Genie 2 (Scientific Industries, Inc., Bohemia, NY).
• an 8 wt% aqueous PVA solution was prepared by dissolving 4.8 g of PVA in 55.2 g of deionized water.
• the PVA solution was added to a 100-mL resin kettle (Kontes Glass, Inc., Vineland, NJ) fitted with a truebore stirrer and a 1.5-in. teflon turbine impeller.
• the polymer solution was then added to the PVA processing medium by pouring through a long-stem 7-mm bore funnel. During this addition, the PVA solution was being stirred at about 650 rpm.
• the contents of the resin kettle were transferred to 3.5 L of deionized water contained in a 4-L beaker and being stirred at about 800 rpm with a 2-in. stainless steel impeller.
• microcapsules were stirred in the deionized water for about 30 minutes, collected by centrifugation, washed twice with deionized water to remove any residual PVA, and were then collected by freeze drying.
• the microcapsule products consisted of spherical particles about 1 to 10 micrometers in diameter.
• Other microcapsules, such as staphylococcal enterotoxin B microcapsules, can be made in a similar manner.
• the TNP-KLH content of the antigen-loaded microcapsules was determined by weighing out 10 mg of antigen-loaded microcapsules in a 12-mL centrifuge tube. Add 3.0 mL of methylene chloride to the tube and vortex to dissolve the poly(DL-lactide-co-glycolide). Next, add 3.0 mL of deionized water to the tube and vortex vigorously for 1 minute. Centrifuge the contents of the centrifuge tube to separate the organic and aqueous layers. Transfer the aqueous layer to a 10-mL volumetric flask. Repeat the extraction combining the aqueous layers in the volumetric flask.
• TNP-KLH in the flask is then quantified using a protein assay.
• the microcapsules contained 0.2% TNP-KLH by weight.
• the staphylococcal enterotoxin B content of staphylococcal enterotoxin B microcapsules can be quantified in a similar manner.
• mice polystyrene microcapsules loaded with the fluorescent dye coumarin.
• Unanesthetized, fasted BALB/c mice were administered 0.5 mL of a 100 mg/mL suspension of various sized fluorescent microcapsules (less than 5 micrometers or 8 to 50 micrometers in diameter) in tap water into the stomach using a feeding needle.
• the mice were sacrificed and the small intestine excised.
• Onecentimeter sections of gut containing a discrete Peyer's patch were isolated, flushed of lumenal contents, everted and snap frozen. Frozen sections were prepared and examined under a fluorescence microscope to observe the number, location and size of the microcapsules which were taken up into the Peyer's patch from the gut lumen.
• microcapsules >10 micrometers in diameter were not absorbed into the Peyer's patches while microcapsules of 1 to 10 micrometers in diameter were rapidly and selectively taken up.
• microcapsules composed of biodegradable wall materials would serve as an effective means for the targeted delivery of antigens to the lymphoreticular tissues for the induction of immunity at mucosal surfaces.
• mice were administered biodegradable microcapsules containing the fluorescent dye coumarin-6 as a suspension in tap water via a gastric tube.
• the microcapsule wall material chosen for these studies consisted of 85:15 poly (DL-lactide-co-glycolide) due to its ability to resist significant bioerosion for a period of six weeks.
• three representative Peyer's patches, the major mesenteric lymph nodes and the spleens from individual mice were removed, processed and serial frozen sections prepared. When viewed with a fluorescence microscope using appropriate excitation and barrier filters the coumarin exhibited a deep green fluorescence which allowed the visual detection of microcapsules substantially less than 1 micrometer in diameter.
• the efficiency of uptake for the entrapped microcapsules must be several orders of magnitude greater than that of the microcapsules present in the gut lumen, but above the mucus layer.
• Microcapsules of various sizes were observed within the Peyer's patches at all time points tested as shown in Table 1.
• the proportion of ⁇ 2 micrometers (45-47%), 2-5 micrometers (31-35%) and >5 micrometers (18-23%) microcapsules remained relatively constant.
• the small ( ⁇ 2 micrometers) and medium (2-5 micrometers) microcapsules ceased to predominate and the large (>5 micrometers) microcapsules became the numerically greatest species observed.
• This shift was concurrent with the decrease in total microcapsule numbers in the Peyer's patches observed on and after Day 7.
• Consistent with the preferential migration of the small and medium microcapsules out of the Peyer's patches are the data pertaining to the location of microcapsules within the architecture of the Peyer's patches.
• a microcapsule was observed within the Peyer's patch, it was noted to be either relatively close to the dome epithelium where it entered the Peyer's patch (within 200 micrometers) or deeper within the lymphoid tissue ( ⁇ 200 micrometers from the closest identifiable dome epithelium) (Table 1).
• Microcapsules observed deep within the Peyer's patch tissue were almost exclusively of small and medium diameter. At 1 day post-administration, 92% of the microcapsules were located close to the dome epithelium.
• the proportion of deeply located microcapsules increased through Day 4 to 24% of the total, and thereafter decreased with time to approximately 2% at Day 14 and later.
• the small and medium microcapsules migrate through and out of the Peyer's patches, while the large (>5 micrometers) microcapsules remain within the dome region for an extended period of time.
• microcapsules were observed in the mesenteric lymph nodes at 1 day postadministration, and the numbers progressively increased through Day 7, as shown in Table 2. After Day 7, the numbers decreased but were still detectable on Day 35.
• the size distribution clearly showed that microcapsules >5 micrometers in diameter did not enter this tissue, and the higher proportion of small ( ⁇ 2 micrometers) relative to medium (2-5 micrometers) microcapsules at the earlier time points indicated that the smaller diameter microcapsules migrate to this tissue with greatest efficiency.
• the majority of the microcapsules were located just under the capsule in the subcapsular sinus.
• tissue sections from Peyer's patches, mesenteric lymph node and spleen which contained absorbed 85:15 DL-PLG microcapsules were examined by histochemical and immunohistochemical techniques.
• these studies clearly showed that the microcapsules which were absorbed into the Peyer's patches were present within macrophage-like cells which were stained by periodic acid Schiff's reagent (PAS) for intracellular carbohydrate, most probably glycogen, and for major histocompatibility complex (MHC) class II antigen.
• PAS periodic acid Schiff's reagent
• MHC major histocompatibility complex
• the microcapsules observed in the mesenteric lymph nodes and in the spleen were universally found to have been carried there within these PAS and MHC class II positive cells.
• the antigen containing microcapsules have been internalized by antigenpresenting accessory cells (APC) in the Peyer's patches, and these APC have disseminated the antigenmicrocapsules to other lymphoid tissues.
• APC antigenpresenting accessory cells
• Microcapsules ⁇ 5 micrometers in diameter extravasate from the Peyer's patches within APC and release the antigen in lymphoid tissues which are inductive sites for systemic immune responses.
• the microcapsules 5 to 10 micrometers in diameter remain in the Peyer's patches, also within APC, for extended time and release the antigen into this slgA inductive site.
• microcapsules prepared from 7 of the 10 excipients, were absorbed and were predominantly present in the dome region of the Peyer's patches 48 hours after oral administration of a suspension containing 20 mg of microcapsules, as shown in Table 3. None of the microspheres were seen to penetrate into tissues other than the Peyer's patches.
• ethyl cellulose the efficiency of absorption was found to correlate with the relative hydrophobicity of the excipient.
• the cellulosics were not absorbed.
• microcapsules regulate the targeting of the microcapsules through the efficiency of their absorption from the gut lumen by the Peyer's patches, and that this is a surface phenomenon. Therefore, alterations in the surface characteristics of the microcapsules, in the form of chemical modifications of the polymer or in the form of coatings, can be used to regulate the efficiency with which the microcapsules target the delivery of bioactive agents to mucosally-associated lymphoid tissues and to APC.
• coatings which may be employed but are not limited to, chemicals, polymers, antibodies, bioadhesives, proteins, peptides, carbohydrates, lectins and the like of both natural and man made origin.
• mice BALB/c mice, 8 to 12 weeks of age, were used in these studies.
• Trinitrophenyl - Keyhole Limpet Hemocyanin Hemocyanin from the keyhole limpet (KLH) Megathura crenulate was purchased from Calbiochem (San Diego, CA). It was conjugated with the trinitrophenyl hapten (TNP-KLH) using 2, 4, 6-trinitrobenzene sulfonic acid according to the procedure of Rittenburg and Amkraut (Rittenburg, M.B. and Amkraut, A.A. Immunogenicity of trinitrophenyl-hemocyanin: Production of primary and secondary anti-hapten precipitins. J. Immunol. 97:421; 1966). The substitution ratio was spectrophotometrically determined to be TNP 861 -KLH using a molar extinction coefficient of 15,400 at a wavelength of 350 nm and applying a 30% correction for the contribution of KLH at this wavelength.
• Staphylococcal Enterotoxin B Vaccine A formalinized vaccine of staphylococcal enterotoxin B (SEB) was prepared as described by Warren et al. (Warren, J.R., Spero, L. and Metzger, J.F. Antigenicity of formalininactivated staphylococcal enterotoxin B. J. Immunol. 111:885; 1973). In brief, 1 gm of enterotoxin was dissolved in 0. 1 M sodium phosphate buffer, pH 7.5, to 2 mg/mL. Formaldehyde was added to the enterotoxin solution to achieve a formaldehyde: enterotoxin mole ratio of 4300:1.
• the solution was placed in a slowly shaking 37oC controlled environment incubator-shaker and the pH was monitored and maintained at 7.5 + 0.1 daily. After 30 days, the toxoid was concentrated and washed into borate buffered saline (BBS) using a pressure filtration cell (Amicon), and sterilized by filtration.
• BBS borate buffered saline
• Amicon a pressure filtration cell
• mice were administered four doses (0.5 mL) of lavage solution [25 mM NaCl, 40 mM Na 2 SO 4 , 10 mM KCl, 20 mM NaHCO 3 , and 48.5 mM poly(ethylene glycol), osmolarity of 530 mosM] at 15-minute intervals (Elson, CO., Ealding, W. and Lefkowitz, J. A lavage technique allowing repeated measurement of IgA antibody on mouse intestinal secretions. J. Immunol. Meth. 67:101; 1984). Fifteen minutes after the last dose of lavage solution, the mice were anesthetized and after an additional 15 minutes they were administered 0.1 mg pilocarpine by ip injection.
• lavage solution 25 mM NaCl, 40 mM Na 2 SO 4 , 10 mM KCl, 20 mM NaHCO 3 , and 48.5 mM poly(ethylene glycol), osmolarity of 530 mosM
• Saliva Concurrent with the intestinal discharge, a large volume of saliva is secreted and 0.25 mL was collected into a pasteur pipette by capillary action. Twenty microliters each of trypsin inhibitor, PMSF, sodium azide and FCS was added prior to clarification.
• Bronchial-Alveolar Wash Fluids Bronchial-Alveolar wash fluids were obtained by lavaging the lungs with 1.0 mL of PBS. An animal feeding needle was inserted intratracheally and fixed in place by tying with suture material. The PBS was inserted and withdrawn 5 times to obtain washings, to which were added 20 microliters each of trypsin inhibitor, PMSF, sodium azide, and FCS prior to clarification by centrifugation.
• Immunochemical Reagents Solid-phase absorbed and affinity-purified polyclonal goat IgG antibodies specific for murine IgM, IgG and IgA were obtained commercially (Southern Biotechnology Associates, Birmingham, AL). Their specificity in radioimmunoassays was tested through their ability to bind appropriate purified monoclonal antibodies and myeloma proteins. 6. Solid-Phase Radioimmunoassays. Purified antibodies were labeled with carrier-free Na 125 l (Amersham) using the chloramine T method [Hunter, W.M. Radioimmunoassay. In: Handbook of Experimental Immunology, M. Weir (editor). Blackwell Scientific Publishing, Oxford, p. 14.1; 1978).
• Immulon Removawell assay strips (Dynatech) were coated with TNP conjugated bovine serum albumin (BSA) or staphylococcal enterotoxin B at 1 microgram/mL in BBS overnight at 4oC. Control strips were left uncoated but all strips were blocked for 2 hours at room temperature with 1% BSA in BBS, which was used as the diluent for all samples and 1251-labeled reagents. Samples of biologic fluids were appropriately diluted, added to washed triplicate replicate wells, and incubated 6 hours at room temperature. After washing, 100,000 cpm of 1251-labeled isotype-specific antiimmunoglobulin was added to each well and incubated overnight at 4oC. Following the removal of unbound
• EXAMPLE 1 Adjuvant Effect Imparted by Microencapsulation-Intraperitoneal Administration. Research in our laboratories has shown that microencapsulation results in a profoundly heightened immune response to the incorporated antigen or vaccine in numerous experimental systems. An example is provided by the direct comparison of the level and isotype distribution of the circulating antibody response to Staphylococcal enterotoxin B, the causative agent of Staphylococcal food poisoning, following immunization with either soluble or microencapsulated enterotoxoid.
• mice were administered various doses of the toxoid vaccine incorporated in 50:50 poly (DL-lactide-co-glycolide) microcapsules, or in soluble form, by intraperitoneal (IP) injection.
• IP intraperitoneal
• plasma samples were obtained and assayed for anti-toxin activity by end-point titrationin in isotype-specific immunoradiometric assays (Table 4).
• the optimal dose of soluble toxoid 25 micrograms
• elicited a characteristically poor immune response to the toxin which was detected only in the IgM isotype.
• toxoid incorporated within microcapsules induced not only an IgM response, but an IgG response which was detectable at a plasma dilution of 1/2,560 on Day 20 post immunization.
• larger doses of toxoid could be administered in microencapsulated form without decreasing the magnitude of the response, as is seen with the 50 microgram dose of soluble toxoid.
• the measured release achieved with the microcapsules allows for 4-5 times the dose to be administered without causing high zone paralysis, resulting in substantially heightened immunity. This adjuvant activity is even more pronounced following secondary (Table 5) and tertiary immunizations (Table 6).
• the Day 20 IgG anti-toxin response following secondary immunization was 512 times higher in mice receiving 50 micrograms of microencapsulated toxoid than in mice receiving the optimal dose of soluble toxoid. Further, tertiary immunization with the soluble toxoid at its optimal dose was required to raise an antibody response to the toxin which was equivalent to that observed following a single immunization with 100 micrograms of microencapsulated enterotoxoid.
• Adjuvant activity of equal magnitude has been documented to common laboratory protein antigens such as haptenated keyhole limpet hemocyanin and influenza virus vaccine.
• the present delivery system was found to be active following intramuscular or subcutaneous (SC) injection. This was investigated by directly comparing the time course and level of the immune response following IP and SC injection into groups of mice, as shown in Table 7.
• One hundred micrograms of enterotoxoid in microspheres administered by SC injection at 4 sites along the backs of mice stimulated a peak IgG anti-toxin response equivalent to that observed following IP injection. Some delay in the kinetics of anti-toxin appearance were observed. However, excellent antibody levels were attained, demonstrating the utility of injection at sites other than the peritoneum.
• the IP and SC routes were again equivalent with respect to peak titer, although the delayed response of the SC route was again evident, as shown in Table 8.
• EXAMPLE 1 The Adjuvant Effect Imparted by Microencapsulation is Not the Result of Adjuvant Activity Intrinsic to the Polymer.
• microspheres in this size range are readily phagocytized by antigen processing and presenting cells. Therefore, targeted delivery of a comparatively large dose of nondegraded antigen directly to the cells responsible for the initiation of immune responses to T cell-dependent antigens must also be considered.
• the microcapsules may possess intrinsic immunopotentiating activity through their ability to activate cells of the immune system in a manner analogous to adjuvants such as bacterial lipopolysaccharide or muramyl-di-peptide. Immunopotentiation by this latter mechanism has the characteristic that it is expressed when the adjuvant is administered concurrently with the antigen.
• the antibody response to 100 micrograms of microencapsulated enterotoxoid was compared to that induced following the administration of an equal dose of enterotoxoid mixed with placebo microspheres containing no antigen.
• the various antigen forms were administered by IP injections into groups of 10 BALB/c mice and the plasma IgM and IgG enterotoxinspecific antibody responses determined by end-point titration RIAs, as shown in Table 9.
• the plasma antibody response to a bolus injection of the optimal dose of soluble enterotoxoid was characteristically poor and consisted of a peak IgM titer of 800 on day 10 and a peak IgG titer of 800 on day 20.
• Administration of an equal dose of microencapsulated enterotoxoid induced a strong response in both the IgM and IgG isotypes which was still increasing on day 30 after immunization.
• Coadministration of soluble enterotoxoid and a dose of placebo microspheres equal in weight, size and composition to those used to administer encapsulated antigen did not induce a plasma anti-toxin response which was significantly higher than that induced by soluble antigen alone.
• EXAMPLE 2 Retarding the Antigen Release Rate from 1-10 Micrometer Microcapsules Increases the Level of the Antibody Response and Delays the Time of the Peak Response.
• the first injection is given to afford a primary response
• the second injection is given to afford a secondary response
• a third injection is given to afford a tertiary response.
• Multiple injections are needed because repeated interaction of the antigen with immune system cells is required to stimulate a strong immunological response.
• a patient After receiving the first injection of vaccine, a patient, therefore, must return to the physician on several occasions to receive the second, third, and subsequent injections to acquire protection. Often patients never return to the physician to get the subsequent injections.
• the vaccine formulation that is injected into a patient may consist of an antigen in association with an adjuvant. For instance, an antigen can be bound to alum.
• the use of the antigen/adjuvant combination is important in that the adjuvant aids in the stimulation of an immune response.
• the administration of the antigen improves the immune response of the body to the antigen.
• the second and third administrations or subsequent administrations do not necessarily require an adjuvant.
• Alza Corporation has described methods for the continuous release of an antigen and an immunopotentiator (adjuvant) to stimulate an immune response (U.S. Patent No. 4,455,142).
• This invention differs from the Alza patent in at least two important manners. First, no immunopotentiator is required to increase the immune response, and second, the antigen is not continuously released from the delivery system.
• the present invention concerns the formulation of vaccine (antigen) into microcapsules (or microspheres) whereby the antigen is encapsulated in biodegradable polymers, such as poly (DL-lactide-co-glycolide). More specifically, different vaccine microcapsules are fabricated and then mixed together such that a single injection of the vaccine capsule mixture improves the primary immune response and then delivers antigen in a pulsatile fashion at later time points to afford secondary, tertiary, and subsequent responses.
• biodegradable polymers such as poly (DL-lactide-co-glycolide).
• the mixture of microcapsules consists of small and large microcapsules.
• the small microcapsules less than 10 microns, preferably less than 5 micrometers, or more preferable 1 to 5 micrometers, potentiate the primary response (without the need of an adjuvant) because the small microcapsules are efficiently recognized and taken up by macrophages.
• the microcapsules inside of the macrophages then release the antigen which is subsequently processed and presented on the surface of the macrophage to give the primary response.
• microcapsules greater than 5 micrometers, preferably greater than 10 microns, but not so large that they cannot be administered for instance by injection, preferably less than 250 micrometers, are made with different polymers so that as they biodegrade at different rates, they release antigen in a pulsatile fashion.
• the composition of the antigen microcapsules for the primary response is basically the same as the composition of the antigen microcapsules used for the secondary, tertiary, and subsequent responses. That is, the antigen is encapsulated with the same class of biodegradable polymers. The size and pulsatile release properties of the antigen microcapsules then maximizes the immune response to the antigen.
• the preferred biodegradable polymers are those whose biodegradation rates can be varied merely by altering their monomer ratio, for example, poly(DL-lactide-co-glycolide), so that antigen microcapsules used for the secondary response will biodegrade faster than antigen microcapsules used for subsequent responses, affording pulsatile release of the antigen.
• by controlling the size of the microcapsules of basically the same composition one can maximize the immune response to an antigen. Also important is having small microcapsules (microcapsules less than 10 micrometers, preferably less than 5 micrometers, most preferably 1 to 5 micrometers) in the mixture of antigen microcapsules to maximize the primary response.
• an immune enhancing delivery system such as small microcapsules
• an immune enhancing delivery system becomes even more important when one attempts to illicit an immune response to less immunogenic compounds such as killed vaccines, subunit vaccines, low-molecular-weight vaccines such as peptides, and the like.
• EXAMPLE 1 Coadministration of Free and Microencapsulated Vaccine.
• a Japanese Encephalitis virus vaccine (Biken) was studied.
• the virus used is a product of the Research Foundation for Microbial Disease of Osaka
• mice immunized with a standard three dose schedule of JE vaccine to the antiviral response of mice immunized with a single administration of JE vaccine consisting of one part unencapsulated vaccine and two parts encapsulated vaccine.
• the JE microcapsules were >10 micrometers. The results of immunizing mice with JE vaccine by these two methods were compared by measuring the serum antibody titers against JE vaccine detected through an ELISA assay.
• the ELISA assay measures the presence of serum antibodies with specificity of JE vaccine components, however, it does not measure the level of virus neutralizing antibody present in the serum.
• the virus neutralizing antibody activity was therefore measured by virus cytopathic effect (CPE) inhibition assays and virus plaque reduction assays. The results of those assays are presented here.
• CPE virus cytopathic effect
• mice which receive no immunization consisting of (1) untreated control mice which receive no immunization; (2) mice which received 3.0 mg of JE vaccine
• mice which received 3.0 mg of JE vaccine (unencapsulated) on Days 0, 14 and 42 (standard schedule) and (4) mice which received 3.0 mg of JE vaccine (unencapsulated) and 3.0 mg of JE vaccine (encapsulated) on day 0 were studied.
• the untreated controls provide background virus neutralization titers against which immunized animals can be compared.
• the animals receiving a single 3.0 mg dose of JE vaccine on Day 0 provide background neutralization titers against which animals receiving unencapsulated vaccine in conjunction with encapsulated vaccine can be compared. This comparison provides evidence that the administration of encapsulated vaccine augments the immunization potential of a single 3.0 mg dose of unencapsulated vaccine.
• the animals receiving 3 doses of unencapsulated vaccine provide controls against which the encapsulated vaccine group can be compared so as to document the ability of a single injection consisting of both nonencapsulated and encapsulated vaccine to produce antiviral activity comparable to a standard three dose immunization schedule.
• mice receiving encapsulated vaccine had a two-fold increase in the average serum neutralizing titer from Day 49 to Day 77.
• the animals receiving encapsulated vaccine Group 4 continued to demonstrate increases in serum virus neutralizing activity throughout the timepoints examined.
• mice receiving encapsulated JE vaccine had a two-fold increase in the average serum neutralizing titer from Day 49 to Day 77.
• the animals receiving encapsulated vaccine Group
• copolymer microcapsule delivery system One advantage of the copolymer microcapsule delivery system is the ability to control the time and/or rate at which the incorporated material is released. In the case of vaccines this allows for scheduling of the antigen release in such a manner as to maximize the antibody response following a single administration.
• a pulsed release analogous to conventional booster immunizations.
• the possibility of using a pulsed release profile was investigated by subcutaneously administering 100 micrograms of enterotoxoid to groups of mice either in 1-10 micrometer (50:50 DL-PLG; 1.51 wt% enterotoxoid), 20-125 mm (50:50 DL-PLG; 0.64 wt% enterotoxoid) or in a mixture of 1-10 micrometer and 20125 micrometer microcapsules in which equal parts of the enterotoxoid were contained within each size range.
• the groups of mice were bled at 10 day intervals and the plasma IgG responses were determined by endpoint titration in isotype-specific immunoradiometric assays employing solid-phase absorbed enterotoxin ( Figure 1).
• the plasma IgG response was detected on day 10, rose to a maximal titer of 102,400 on days 30 and 40, and decreased through day 60 to 25,600.
• the response to the toxoid administered in 20-125 micrometer microcapsules was delayed until day 30, and thereafter increased to a titer of 51,200 on days 50 and 60.
• the concomitant administration of equal parts of the toxoid in 1-10 and 20-125 micrometer microcapsules produced an IgG response which was for the first 30 days essentially the same as that stimulated by the 1-10 micrometer microcapsules administered alone.
• the antibody response obtained through the coadministration of 1-10 and 20-125 micrometer enterotoxoid-containing microcapsules is consistent with a two phase (pulsed) release of the antigen.
• the first pulse results from the rapid ingestion and accelerated degradation of the 1-10 micrometer particles by tissue histiocytes, which results in a potentiated primary immune response due to the efficient loading of high concentrations of the antigen into these accessory cells, and most probably their activation.
• the second phase of antigen release is due to the biodegradation of the 20-125 micrometer microcapsules, which are too large to be ingested by phagocytic cells. This second pulse of antigen is released into a primed host and stimulates an anamnestic immune response.
• a single injection vaccine delivery system can be constructed which potentiates antibody responses (1-10 micrometer microcapsules), and which can deliver a timed and long lasting secondary booster immunization (20-125 micrometer microcapsules).
• a timed and long lasting secondary booster immunization (20-125 micrometer microcapsules).
• the ratio of the copolymers it is possible to prepare formulations which release even later, in order to provide tertiary or even quaternary boostings without the need for additional injections. Therefore, there exist a number of possible approaches to vaccination by the injectable microcapsules of the present invention.
• microcapsules preferably 1 to 5 micrometers
• these include multiple injections of small microcapsules, preferably 1 to 5 micrometers, that will be engulfed by macrophages and obviate the need for immunopotentiators, as well as mixtures of free antigen for a primary response in combination with microcapsulated antigen in the form of microcapsules having a diameter of 10 micrometers or greater that release the antigen pulsatile to potentiate secondary and tertiary responses and provide immunization with a single administration.
• a combination of small microcapsules for a primary response and larger microcapsules for secondary and later responses may be used, thereby obviating the need for both immunopotentiators and multiple injections.
• EXAMPLE 1 Orally-Administered Microspheres Containing TNP-KLH Induce Concurrent Circulating and Mucosal Antibody Responses to TNP.
• Microcapsules containing the haptenated protein antigen trinitrophenyl-keyhole limpet hemocyanin (THP-KLH) were prepared using 50:50 DL-PLG as the excipient. These microcapsules were separated according to size and those in the range of 1 to 5 micrometers in diameter were selected for evaluation. These microcapsules contained 0.2% antigen by weight.
• mice Their ability to serve as an effective antigen delivery system when ingested was tested by administering 0.5 mL of a 10 mg/mL suspension (10 micrograms antigen) in bicarbonate buffered sterile tap water via gastric incubation on 4 consecutive days. For comparative purposes an additional group of mice was orally immunized in parallel with 0.5 mL of 20 micrograms/mL solution of unencapsulated TNP-KLH. Control mice were orally administered diluent only.
• serum, saliva and gut secretions were obtained from 5 fasted mice in each group. These samples were tested in isotype-specific radioimmunoassays to determine the levels of TNP-specific and total antibodies of the IgM, IgG and IgA isotypes (Table 13). The samples of saliva and gut secretions contained antibodies which were almost exclusively of the IgA class. These results are consistent with previous studies and provide evidence that the procedures employed to collect these secretions do not result in contamination with serum. None of the immunization protocols resulted in significant changes in the total levels of immunoglobulins present in any of the fluids tested.
• EXAMPLE 2 Orally Administered Microcapsules Containing SEB Toxoid Induce Concurrent Circulating and Mucosal Anti-SEB Toxin Antibodies.
• Table 14 show the plasma end point titers of the IgM and IgG anti-toxin responses for the Day 20 time point after the primary, secondary and tertiary oral immunizations. Mice receiving the vaccine incorporated in microcapsules exhibited a steady rise in plasma antibodies specific to the toxin with each immunization while soluble enterotoxoid was ineffective. This experiment employed the same lot of microcapsules and was performed and assayed in parallel with the experiments presented in Tables 4, 5 and 6 above.
• saliva and gut wash samples were obtained and assayed for toxin-specific antibodies of the IgA isotype (Table 15).
• saliva and gut wash samples were obtained and assayed for toxin-specific antibodies of the IgA isotype (Table 15).
• the ingestion of an equal amount of the toxoid vaccine incorporated into microcapsules resulted in a substantial slgA anti-toxoid response in both the saliva and gut secretions. It should be pointed out that the gut secretions from each mouse are diluted into a total of 5 mL during collection.
• Vaccine Microcapsules Administered Intratracheally.
• EXAMPLE 1 Intratracheally Administered Microcapsules Containing SEB Toxoid Induce Concurrent Circulating and Mucosal Anti-Toxin Antibodies.
• Folliculi lymphatic aggregati similar to the Peyer's patches of the gastrointestinal tract are present in the mucosally-associated lymphoid tissues found at other anatomical locations, such as the respiratory tract. Their function is similar to that of the Peyer's patches in that they absorb materials from the lumen of the lungs and are inductive sites for antibody responses which are characterized by a high proportion of slgA.
• the feasibility of immunization through the bronchial-associated lymphoid tissue was investigated. Groups of mice were administered 50 microliters of PBS containing 50 micrograms of SEB toxoid in either microencapsulated or nonencapsulated form directly into the trachea. On days 10, 20, 30 and 40 following the immunization, samples of plasma, saliva, gut washings and bronchial-alveolar washings were collected.
• toxin-specific antibodies in the bronchialalveolar washings were induced by the microencapsulated toxoid, but not by the nonencapsulated vaccine (Table 17).
• the kinetics of the appearance of the anti-toxin antibodies in the bronchial secretions was delayed somewhat as compared to the plasma response in that the Day 20 response was only detected in the IgG isotype and was low in comparison to the plateau levels eventually obtained.
• maximal titers of IgG and IgA antitoxin antibodies (1,280 and 320, respectively) were attained by Day 30 and were maintained through Day 40.
• mice were primed by IP immunization with 100 micrograms of microencapsulated SEB toxoid and 30 days later were challenged with 100 micrograms of microencapsulated SEB toxoid by either the IP, oral or IT routes. This was done to directly determine if a mixed immunization protocol utilizing microencapsulated antigen was advantageous with respect to the levels of slgA induced.
• Intratracheal boosting of previously IP immunized mice was particularly effective in the induction of a disseminated mucosal response and elicited the appearance of high concurrent levels of IgG and slgA antibodies in both the samples of bronchial-alveolar and gut secretions.
• Antibodies present within the respiratory tract originate from two different sources. Secretory IgA predominates in the mucus which bathes the nasopharynx and bronchial tree (Soutar, C.A. Distribution of plasma cells and other cells containing immunoglobulin in the respiratory tract of normal man and class of immunoglobulin contained therein. Thorax 31:58; 1976 and Kaltreider, H.B. and Chan, M.K.L. The classspecified immunoglobulin composition of fluids obtained from various levels of canine respiratory tract. J.
• microencapsulated antigen could be administered by both injection and ingestion during a single visit to a physician. By varying the lactide to glycolide ratio in the two doses, the systemically.
• administered dose could be released within a few days to prime the immune system, and the second (oral) dose could be released in the Peyer's patches at a later time to stimulate a boosted mucosal response.
• second (oral) dose could be released in the Peyer's patches at a later time to stimulate a boosted mucosal response.
• IV. ABSORPTION OF PHARMACEUTICALS The following example shows that small microcapsules (less than 5 micrometers, preferably 1 to 5 microns) can also improve the absorption of pharmaceuticals as well as antigens into the body.
• Etretinate (All-E)-9-(4-methoxy-2,3,6,-trimethyl) phenyl-3, 7-dimethyl-2,4,8-nonatetraenoic acid, ethyl ester) was microencapsulated in 50:50 poly(DL-lactide-co-glycolide).
• the microcapsules were 0.5 to 4 micrometers in diameter and contained 37.2 wt% etretinate.
• These etretinate microcapsules, as well as unencapsulated etretinate was administered to mice by oral gavage using 1 wt% Tween 80 in water as a vehicle. Only single doses of 50 mg etretinate/kg were given.
• the microcapsules carry the etretinate to the blood stream via the lymphoidal tissue (Peyer's patches) in the gastrointestinal tract. This same approach should be applicable to increasing the absorption of other drugs, where its application would be especially useful for the delivery of biological pharmaceuticals such as peptides, proteins, nucleic acids, and the like.
• Table 1 Penetration of Coumarin-6 85:15 DL-PLG Microspheres Into and Through the Peyer's Patches Following Oral Administration
• Group 2 3.0 mg unencapsulated JE vaccine IP on Day 10
• Group 3 3.0 mg unencapsulated JE vaccine IP on Days 0, 14 and
• Group 4 3.0 mg unencapsulated + 3.0 mg microencapsulated JE vaccine IP on Day 0
• aGMT Geometric mean titers.
• TNP-KLH Microcapsules Day 14 Gut wash 3 ⁇ 1 130 ⁇ 1 95,368 222
• Enterotoxoid dose ( ⁇ g) Form IgM IgG IgA IgM IgG IgA IgM IgG IgA IgM IgG IgA IgM IgG IgA IgM IgG IgA IgM IgG IgA IgM IgG IgA
• Enterotoxoid dose ( ⁇ g) Form IgM IgG IgA IgM IgG IgA IgM IgG IgA IgM IgG IgA IgM IgG IgA IgM IgG IgA IgM IgG IgA IgM IgG IgA
• 1P 1T 100 1,600 819,200 ⁇ 50 ⁇ 20 2,560 2,560 ⁇ 5 20,480 2,560

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