WO2022109279A1

WO2022109279A1 - Ion-pairing (ip) for producing microparticles

Info

Publication number: WO2022109279A1
Application number: PCT/US2021/060105
Authority: WO
Inventors: Hong Wang; Zimeng WANG
Original assignee: Phosphorex, Inc.
Priority date: 2020-11-19
Filing date: 2021-11-19
Publication date: 2022-05-27

Abstract

The invention described herein provides a method to enhance the encapsulation of certain otherwise hydrophilic compounds (such as hydrophilic proteins and hydrophilic small molecule compounds) with polymers into microspheres or nanoparticles, by ion-pairing with a hydrophobic counter ion to form a ion-pairing (IP) complex, such as a hydrophobic ion-pairing (HIP) complex.

Description

ION-PAIRING (IP) FOR PRODUCING MICROPARTICLES

REFERENCE TO RELATED APPLICATIONS

This International Patent Application claims the benefit of the filing dates of U.S. Provisional Patent Application Nos. 63/115695, filed on November 19, 2020, and 63/153479, filed on February 25, 2021, the entire contents of each of the referenced applications are incorporated by reference herein.

BACKGROUND OF THE INVENTION

Compared to small molecular drugs, biologies, such as peptide and protein APIs (Active Pharmaceutical Ingredients), usually have greater efficacy and more applications, and are the fastest growing segment of the pharmaceutical market. However, these highly potent therapeutics require frequent administration due to their short biological half-lives.

Controlled delivery of biologies from sustained release microspheres can potentially result in improved bioavailability, reduced toxicity, simplified dosing regimens, improved patient adherence, and enhanced overall efficacy.

The most commonly employed technique to encapsulate peptides or proteins into biodegradable microspheres is water-in-oil-in-water (W/O/W) double emulsion solvent evaporation method. In this process, protein in aqueous solution is first emulsified with an organic solution containing the (biodegradable) polymer to form a w/o (water-in-oil) primary emulsion. Subsequently, this primary emulsion is added to a large quantity of external aqueous phase containing a surfactant (e.g., polyvinyl alcohol, PVA). The solvent in the resulting mixture is then stirred to allow the organic solvent to evaporate, and the resulting microparticles are separated by centrifugation or other suitable methods.

However, one of the limiting factors in developing microspheres formulation of peptide or protein therapeutics is their hydrophilic nature, which cause them to partition poorly into polymer matrix, and rapidly penetrate to the external aqueous phase during encapsulation process, leading to poor encapsulation efficiency.

In addition to peptides and proteins, some small molecule APIs are very hydrophilic and water-soluble, and as a result, are also difficult to encapsulate into microparticles. Covalent conjugation to a hydrophobic group through a labile bond is generally used to convert a hydrophilic API to hydrophobic API. The hydrophobic API is essentially a prodrug that can be cleaved to form the original API after delivery. However, covalent modification of APIs results in the creation of a new molecular entity, which requires additional regulatory approval.

Thus, there is a need to develop new methods to efficiently encapsulate hydrophilic APIs, such as peptides, proteins and water-soluble small molecules, into microparticles.

SUMMARY OF THE INVENTION

The invention described herein provides a method to encapsulate, in microparticles, certain otherwise hydrophilic APIs or compounds (including small molecule chemical compounds with M.W. of no more than 5,000 Da, 2,000 Da, 1,500 Da, 1,000 Da, 500 Da, 300 Da, 200 Da, or 100 Da), particularly hydrophilic protein- or peptide-based biological therapeutic agents, to confer such hydrophilic APIs / agents higher solubility in organic solvent and higher compatibility with (biodegradable) polymers. The invention facilitates the encapsulation (e.g., through emulsion methods) of such hydrophilic APIs / agents as microparticles in biodegradable polymers, usually achieving high loading (e.g., >10%, 15%, 20%, 25%, 30% or higher loading).

While not wishing to be bound by any particular theory, one possible mechanism that the ion-pairing method of the invention can achieve such effect is increased hydrophobicity of the overall ion-pair, though the overall ion-pair may not necessarily be highly hydrophobic or even hydrophobic. In this case, the APIs, including small molecule compounds, peptides and proteins, will have reduced aqueous solubility, can partition largely into polymer matrix during the encapsulation process, or be dissolved in organic phase along with (biodegradable) polymers directly. With hydrophobically modified APIs (e.g., small molecules, peptides and proteins) dissolved in organic solvent containing the (biodegradable) polymer, an O/W single emulsion method could be used alternatively, which tends to give higher encapsulation efficiency, compared to W/O/W method.

Thus, in certain embodiments, the resulting ion-pair (IP) is hydrophobic. In other embodiments, the the resulting ion-pair (IP) is not hydrophobic. In yet other embodiments, the resulting ion-pair (IP) is hydrophilic.

Further, while not wishing to be bound by any particular theory, it is conceivable that another independent mechanism for achieving such effect, is that the increased overall size and other physical chemical property (such as diffusion) changes of the ion-paired APIs (small molecules and polypeptides), as compared to the original APIs, further facilitates the loading of the APIs into the microparticles and/or the sustained release profile of the APIs from the microparticles.

Thus in one aspect, the invention provides a method of encapsulating a hydrophilic compound (e.g., a hydrophilic polypeptide or a hydrophilic small molecule compound) having at least one net charge in a polymer matrix to form a microparticle, the method comprising contacting the hydrophilic compound with a counter ion of opposite charge (e.g., a hydrophobic counter ion of opposite charge) to form an ion-pair (IP) complex (e.g., a hydrophobic IP complex (HIP complex)), and encapsulating the IP complex in the polymer through an emulsion process.

In certain embodiments, the IP complex is formed in situ.

For example, in certain embodiments, the emulsion process is a w/o/w (water-in-oil- in-water) double emulsion process comprising the steps of: (a) emulsifying an aqueous phase in a larger volume of an organic phase to form a water-in-oil (w/o) primary emulsion, wherein: (1) the aqueous phase is formed by dissolving the hydrophilic compound in an aqueous solvent; (2) the organic phase is formed by dissolving the polymer and the (hydrophobic) counter ion in an organic solvent; and, (3) the IP complex forms in situ upon contacting the hydrophilic compound in the aqueous phase with the (hydrophobic) counter ion in the organic phase; (b) emulsifying said primary emulsion in a larger volume of an external aqueous phase comprising a surfactant to form the w/o/w double emulsion; (c) removing organic solvent (e.g., by evaporation); and, (d) isolating the resulting microparticle.

In certain embodiments, the emulsion process is an o/w (oil-in-water) emulsion process comprising the steps of: (a) emulsifying an organic phase in a larger volume of an aqueous phase to form an oil-in-water (o/w) emulsion, wherein: (1) the aqueous phase is formed by dissolving the hydrophilic compound in an aqueous solvent; (2) the organic phase is formed by dissolving the polymer and the (hydrophobic) counter ion in an organic solvent; and, (3) the IP complex forms in situ upon contacting the hydrophilic compound in the aqueous phase with the (hydrophobic) counter ion in the organic phase; (b) removing organic solvent (e.g., by evaporation); and, (c) isolating the resulting microparticle.

In certain embodiments, the IP complex is pre-formed.

For example, in certain embodiments, the emulsion process is an o/w (oil-in-water) emulsion process comprising the steps of: (a) emulsifying an organic phase in a larger volume of an aqueous phase to form an oil-in-water (o/w) emulsion, wherein: (1) the organic phase is formed by dissolving the polymer and the IP complex in an organic solvent; and, (2) the IP complex is pre-formed and isolated as a water-insoluble precipitate, by dissolving the hydrophilic compound and the (hydrophobic) counter ion in an aqueous solvent, or a mixture of the aqueous solvent and a second solvent miscible thereto; and, (b) removing organic solvent (e.g., by evaporation); and, (c) isolating the resulting microparticle.

In certain embodiments, the polymer is a biodegradable polymer selected from: polylactide (PLA) (such as poly(D,L-lactide) or PDLLA, poly(L-lactide) or PLLA, and poly(D-lactide) or PDLA); poly(lactide-co-glycolide) (PLGA); polyhydroxyalkanoate (PHA); polycaprolactone (PCL); and copolymers and mixtures thereof.

In certain embodiments, the hydrophilic compound is a hydrophilic therapeutic protein or therapeutic peptide.

In certain embodiments, the hydrophilic compound has one or more positive charge, and the (hydrophobic) counter ion is an anionic (hydrophobic) compound selected from: Sodium Dodecyl Sulphate (SDS), dextran sulphate (DS) and salt thereof (such as dextran sulfate sodium salt) optically with an average molecular weight of about 9,000-11,000 Da, 19,000-21,000 Da, 29,000-31,000 Da, 39,000-41,000 Da, or >500,000 Da, docusate or salt thereof (such as sodium salt), fatty acids (e.g., capric acid, or stearic acid), polyacids (e.g., polymerized high molecular weight carbon chain (e.g., alkyl chain) having multiple attached / branched carbpxyl groups), pamoic acid or PA, dioctyl sulfosuccinic acid, phospholipids, bile acids such as cholic acid and deoxycholic, or a mixture thereof.

In certain embodiments, the hydrophilic compound has one or more negative charge, and the (hydrophobic) counter ion is a cationic (hydrophobic) compound selected from: amine-based surfactants, lipids, polymers, and other hydrophobic molecules.

In certain embodiments, the organic solvent is chloroform, dichloromethane, ethyl acetate, benzyl alcohol, or a water-miscible solvent (such as alcohol, acetane, DMSO, DMF, THF, and acetonitrile).

In certain embodiments, the aqueous solvent is a pH-adjusted water or buffered solution.

In certain embodiments, the surfactant is a sorbitan fatty acid ester (such as sorbitan trioleate, polyoxyethylated sorbitan monooleate and other ethoxylated fatty acid esters of sorbitan), a phosphatide (such as lecithin), acacia, tragacanth, a polyoxyalkylene derivative of propylene glycol (such as those available under the trademark PLURONICS, especially PLURONICS F68); a polyoxyethylated fat, a polyoxyethylated oleotriglyceride, a linolizated oleotriglyceride, a polyethylene oxide condensation product of fatty alcohol, an alkylphenol or fatty acid or l-methyl-3-(2-hydroxyethyl)imidazolidone-(2).

It should be understood that any embodiment described herein, including those only described in one section of the application under one specific aspect of the invention, can be combined with any other embodiment unless explicitly disclaimed or improper.

DETAILED DESCRIPTION OF THE INVENTION

The invention described herein provides an alternative route to increase API (e.g., small molecule compounds, therapeutic proteins and peptides) size, hydrophobicity, and/or solubility in organic phase, by ion-pairing such API (e.g., small molecule compounds, therapeutic proteins and peptides) with a (hydrophobic) counter ion, through (hydrophobic) ion-pairing (e.g., HIP) complexation. An advantage of this approach is that the resultant products are not considered new molecular entities, and do not require full FDA re-approval.

Although the methods and compositions of the invention are particularly suitable for biologies, such as proteins and polypeptides, theare also effective for non-protein / peptide APIs, including typical small molecule compounds or drugs having molecular weight of less than about 5,000 Da, 2,000 Da, 1,500 Da, 1,000 Da, 500 Da, 300 Da, 200 Da, or 100 Da. For simplicity, the description herein may use therapeutic proteins or polypeptides as illustrative embodiments, but it should be understood that non-protein / non-peptide APIs including the traditional small molecule chemical compounds are encompassed within the scope of the invention, and any specific reference to therapeutic proteins / peptides is construed to include such small molecule compounds / drugs.

IP complex is formed by electrostatic interactions between ionizable groups of API molecules with oppositely charged groups of counter ion species. The resulting IP complex is reversible in nature, and can easily dissociate in the presence of excess amount of oppositely charged ions.

Lipophilicity of the resulting IP complex partly depends on the type of ion-pairing agent employed for IP complexation. The selection of the ion-pairing agents partly depends on certain properties of the APIs (e.g., therapeutic peptides and proteins) being complexed, such as their isoelectric points (pl), molecular weight, and the number of charges on both the APIs (e.g., therapeutic peptides and proteins) and the ion-pairing agents. This approach can be employed for the delivery of numerous APIs, therapeutic peptides and proteins bearing net positive charge, or with a pl of higher than 7, including without limitation: insulin, melittin, leuprolide, bovine serum albumin (BSA) and lysozyme.

For such positively-charged small molecule compound (such as a salt form) or therapeutic peptides and proteins, the chosen ion-pairing agents are anionic (hydrophobic) compounds, usually acids, such as sodium dodecyl sulphate (SDS), dextran sulphate (DS) and salt thereof (such as dextran sulfate sodium salt) optically with an average molecular weight of about 9,000-11,000 Da, 19,000-21,000 Da, 29,000-31,000 Da, 39,000-41,000 Da, or >500,000 Da, docusate or salt thereof (such as sodium salt), fatty acids (e.g., capric acid, or stearic acid), polyacids (e.g., polymerized high molecular weight carbon chain (e.g., alkyl chain) having multiple attached / branched carbpxyl groups), pamoic acid or PA, dioctyl sulfosuccinic acid, phospholipids, bile acids such as cholic acid and deoxycholic, or a mixture thereof.

For APIs, therapeutic peptides and proteins bearing net negative charges, such as peptides or proteins with a pl lower than 7, IP complexes can be formed between the negatively-charged peptides and proteins with positively-charged (hydrophobic) cationic compounds or counter ions.

Preferably, the chosen cationic compounds or counter ions have reduced or limited toxicity, such as amine-based surfactants, lipids, polymers, and other hydrophobic molecules.

Regardless of the types and charges involved, the method generally yields hydrophobic complexes of the API (e.g., small molecules, peptides and proteins), which would improve encapsulation efficiency into microparticles, stabilize the API (e.g., small molecules, peptides and proteins), thus achieving better sustained release of such APIs.

As used herein, microparticles, microspheres, and nanoparticles are terms of art, and may be loosely used interchangeably to refer to a class of particles encapsulating the ion- paired APIs with overlapping size ranges, shapes, and/or physial-chemical properties. In general, microparticles are micron sized particles (e.g., under 1000 micron, 100 micron, 10 micron, etc) while nanoparticles are nanometer sized particles (e.g., under 1 micron, 500 nm, 300 nm, 100 nm, 10 nm etc).

Described below are a few exemplary methods for forming a IP, depending on the specific properties of the APIs and the ion pairing agents.

In certain embodiments, the invention provides in situ ion pairing for a W/O/W double emulsion method. According to this embodiment, the HIP complexation forms in situ during emulsification. For example, the hydrophilic API (e.g., small molecules, therapeutic peptide or protein) is dissolved in an inner aqueous phase, and a (biodegradable) polymer and a hydrophobic ion pairing agent are dissolved in an outer organic phase. During homogenization, HIP forms once the API contacts the ion-pairing agent. As a result, the hydrophilic API is pulled into the organic phase due to the now decreased water solubility of the HIP complex, and is eventually encapsulated in microspheres after the completion of the double emulsion process.

In certain embodiments, the invention provides in situ ion pairing for an O/W emulsion method. Again, the HIP complexation forms in situ during emulsification. For example, a (biodegradable) polymer and a hydrophobic ion pairing agent are dissolved in an inner organic phase, and a hydrophilic API (e.g., small molecules, therapeutic peptide or protein) is dissolved in an external aqueous phase. During homogenization, HIP forms once the API contacts the ion-pairing agent. As a result, the hydrophilic API is pulled into the organic phase due to decreased water solubility of the HIP complex, and is eventually encapsulated in microspheres after the completion of the oil-in-water emulsion process.

In certain embodiments, the invention provides pre-ion pairing for an O/W emulsion method. According to this embodiment, small molecules, proteins and peptides and ionpairing agents are mixed in water, or in a mixture of water and a miscible solvent, to form a water-insoluble precipitate, an IP complex. The IP complex can then be collected by centrifugation, and then dissolved into an organic solvent containing a (biodegradable) polymer as the organic phase in an O/W emulsion. In this case, the IP complex is used as single component in the organic phase.

The API (e.g, small molecules, peptides and proteins) should bear one or more net charge(s), either negative or positive, under IP formation condition, which is obtained by adjusting pH of aqueous phase.

Suitable non-limiting (biodegradable) polymers include: polylactide (PLA) such as poly(D,L-lactide) or PDLLA, poly(L-lactide) or PLLA, and poly(D-lactide) or PDLA; poly(lactide-co-glycolide) (PLGA); polyhydroxyalkanoate (PHA); polycaprolactone (PCL); and copolymers and mixtures thereof.

Suitable organic solvents can be chloroform, dichloromethane, ethyl acetate, benzyl alcohol, or water-miscible solvent such as alcohols, acetane, DMSO, DMF, THF, acetonitrile.

Aqueous phase could be pH-adjusted water or buffered solution. Suitable surfactant for either double emulsion or single emulsion can be: sorbitan fatty acid esters such as sorbitan trioleate, phosphatides such as lecithin, acacia, tragacanth, polyoxyethylated sorbitan monooleate and other ethoxylated fatty acid esters of sorbitan, polyoxyalkylene derivatives of propylene glycol, such as those available under the trademark PLURONICS, especially PLURONICS F68; polyoxyethylated fats, polyoxyethylated oleotriglycerides, linolizated oleotriglycerides, polyethylene oxide condensation products of fatty alcohols, alkylphenols or fatty acids or l-methyl-3-(2-hydroxyethyl)imidazolidone-(2).

As used herein, “polyoxyethylated” means that the substances in question contain polyoxyethylene chains, the degree of polymerization of which generally is between 2 and 200, and preferably, between 10 and 20.

Therapeutic Proteins

As described herein, the terms “therapeutic protein” and “therapeutic (poly)peptide” are used interchangeably, and refer to any therapeutic protein/polypeptide molecules which exhibit biological activity that is associated with the therapeutic protein/polypeptide. The terms “protein,” “polypeptide,” and “peptide” are also used interchangeably.

In one embodiment, the therapeutic protein is a full-length protein.

In another embodiment, the therapeutic protein is a functional domain.

In certain embodiments, the therapeutic protein may be produced and purified from its natural source. Alternatively, the therapeutic protein is a “recombinant therapeutic protein” that includes any therapeutic protein obtained via recombinant DNA technology.

The therapeutic proteins provided herein should not be considered to be exclusive. Rather, as is apparent from the present disclosure provided herein, the methods of the present disclosure are applicable to any protein with at least one net charge, either positive or negative.

In certain embodiments, the therapeutic protein has 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 30, 40 50 or more net charges, either positive net charge or negative net charge.

In certain embodiments, the therapeutic protein has a pl value of 3, 4, 5, 6, 8, 9, 10, or 11.

In certain embodiments, the charge on the therapeuttic protein is partly due to charged side chain groups and/or terminal carboxyl and amino groups.

In certain embodiments, the charge on the therapeuttic protein is partly due to post- translational modification which can be either naturally occurring or engineered. In certain embodiments, the therapeutic protein is wild-type, in other embodiments, it is derivatized by, for example, attaching a linker and/or galactosylating moiety. In other embodiment, it is a variant and/or can contain conservative substitutions, particularly maintaining sequence identity, and/or can be desialylated.

As used herein, “endogenous therapeutic protein” includes a therapeutic protein which originates from the mammal intended to receive treatment. The term also includes therapeutic protein transcribed from a transgene or any other foreign DNA present in said mammal. As used herein, “exogenous therapeutic protein” includes a blood coagulation protein which does not originate from the mammal intended to receive treatment.

As used herein, “plasma-derived therapeutic protein” or “plasmatic” includes all forms of the protein, for example a blood coagulation protein, found in blood obtained from a mammal having the property participating in the coagulation pathway.

In certain embodiments, the therapeutic proteins include: enzymes, antigens, antibodies, receptors, blood coagulation proteins, growth factors, hormones, and ligands.

In certain embodiments, the therapeutic protein is a member of the serpin family of proteins, e.g., A1PI (alpha-1 proteinase inhibitor), or A1AT (alpha-l-antitrypsin), ATR (alpha- 1 -antitrypsin-related protein), AACT or ACT (alpha- 1 -antichymotrypsin), PI4 (proteinase inhibitor 4), PCI or PROCI (protein C inhibitor), CBG (corticosteroid-binding globulin), TBG (thyroxine-binding globulin), AGT (angiotensinogen), centerin, PZI (protein Z-dependent protease inhibitor), PI2 (proteinase inhibitor 2), PA 12 or PLANH2 (plasminogen activator inhibitor-2), SCCA1 (squamous cell carcinoma antigen 1), SCCA2 (squamous cell carcinoma antigen 2), PI5 (proteinase inhibitor 5), PI6 (proteinase inhibitor 6), megsin, PI8 (proteinase inhibitor 8), PI9 (proteinase inhibitor 9), PI10 (proteinase inhibitor 10), epipin, yukopin, PI13 (proteinase inhibitor 13), PI8L1 (proteinase inhibitor 8-like 1), AT3 or ATIII (antithrombin-III), HC-II or HCF2 (heparin cofactor II), PAI1 or PLANH1 (plasminogen activator inhibitor- 1), PN1 (proteinase nexin I), PEDF, (pigment epithelium-derived factor), PLI (plasmin inhibitor), Cl IN or Cl INH (plasma proteinase Cl inhibitor), CBP1 (collagen- binding protein 1), CBP2 (collagen-binding protein 2), PI12 (proteinase inhibitor 12), and PI14 (proteinase inhibitor 14)). The serpins (serine proteinase inhibitors) are a superfamily of proteins (300-500 amino acids in size) that fold into a conserved structure and employ an unique suicide substrate-like inhibitory mechanism (Silverman, G. A., et al., J. Biol. Chem., 276(36):33293-33296 (2001); incorporated by reference in its entirety). In certain embodiments, the therapeutic protein is a member of the coagulation factor family of proteins, e.g., Factor IX (FIX), Factor VIII (FVIII), Factor Vila (FVIIa), Von Willebrand Factor (VWF), Factor FV (FV), Factor X (FX), Factor XI (FXI), Factor XII (FXII), thrombin (FII), protein C, protein S, tPA, PAI-1, tissue factor (TF) and AD AMTS 13 protease.

In certain embodiments, the therapeutic protein include antibodies and antibody-like molecules, including antibody fragments and fusion proteins with antibodies and antibody fragments. These include human, non-human (such as mouse) and non-natural (i.e., engineered) proteins, antibodies, chimeric antibodies, humanized antibodies, and nonantibody binding scaffolds, such as fibronectins, DARPins, knottins, and the like.

In certain embodiments, the therapeutic protein is: Abatacept, Abciximab, Adalimumab, Adenosine deaminase, Ado-trastuzumab emtansine, Agalsidase alfa, Agalsidase beta, Aldeslukin, Alglucerase, Alglucosidase alfa, a- 1 -proteinase inhibitor, Anakinra, Anistreplase (anisoylated plasminogen streptokinase activator complex), Antithrombin III, Antithymocyte globulin, Ateplase, Bevacizumab, Bivalirudin, Botulinum toxin type A, Botulinum toxin type B, Cl -esterase inhibitor, Canakinumab, Carboxypeptidase G2 (Glucarpidase and Voraxaze), Certolizumab pegol, Cetuximab, Collagenase, Crotalidae immune Fab, Darbepoetin-a, Denosumab, Digoxin immune Fab, Dornase alfa, Eculizumab, Etanercept, Factor Vila, Factor VIII, Factor IX, Factor XI, Factor XIII, Fibrinogen, Filgrastim, Galsulfase, Golimumab, Histrelin acetate, Hyaluronidase, Idursulphase, Imiglucerase, Infliximab, Insulin [including recombinant human insulin (“rHu insulin”) and bovine insulin], Interferon-a2a, Interferon- a2b, Interferon-pia, Interferon- P lb, Interferon-ylb, Ipilimumab, L-arginase, L-asparaginase, L-methionase, Lactase, Laronidase, Lepirudin/hirudin, Mecasermin, Mecasermin rinfabate, Methoxy Natalizumab, Octreotide, Ofatumumab, Oprelvekin, Pancreatic amylase, Pancreatic lipase, Papain, Peg-asparaginase, Peg-doxorubicin HC1, PEG-epoetin-P, Pegfilgrastim, Peg-Interferon-a2a, Peg- Interferon- a2b, Pegloticase, Pegvisomant, Phenylalanine ammonia-lyase (PAL), Protein C, Rasburicase (uricase), Sacrosidase, Salmon calcitonin, Sargramostim, Streptokinase, Tenecteplase, Teriparatide, Tocilizumab (atlizumab), Trastuzumab, Type 1 alpha-interferon, Ustekinumab, vW factor. The therapeutic protein can be obtained from natural sources (e.g., concentrated and purified) or synthesized, e.g., recombinantly, and includes antibody therapeutics that are typically IgG monoclonal or fragments or fusions. Particular therapeutic protein, peptide, antibody or antibody-like molecules include Abciximab, Adalimumab, Agalsidase alfa, Agalsidase beta, Aldeslukin, Alglucosidase alfa, Factor VIII, Factor IX, Infliximab, Insulin (including rHu Insulin), L-asparaginase, Laronidase, Natalizumab, Octreotide, Phenylalanine ammonia-lyase (PAL), or Rasburicase (uricase) and generally IgG monoclonal antibodies in their varying formats.

Another particular group includes the hemostatic agents (Factor VIII and IX), Insulin (including rHu Insulin), and the non-human therapeutics uricase, PAL and asparaginase.

In certain embodiments, the therapeutic protein is: insulin, proinsulin, preproinsulin, glutamic acid decarboxylase-65 (GAD-65 or glutamate decarboxylase 2), GAD-67, glucose-6 phosphatase 2 (IGRP or islet-specific glucose 6 phosphatase catalytic subunit related protein), insulinoma-associated protein 2 (IA-2), and insulinoma-associated protein 2p (IA-2P); ICA69, ICA12 (SOX-13), carboxypeptidase H, Imogen 38, GLIMA 38, chromogranin-A, HSP-60, carboxypeptidase E, peripherin, glucose transporter 2, hepatocarcinoma-intestine- pancreas/pancreatic associated protein, SlOOp, glial fibrillary acidic protein, regenerating gene II, pancreatic duodenal homeobox 1, dystrophia myotonica kinase, islet- specific glucose-6-phosphatase catalytic subunit-related protein, and SST G-protein coupled receptors 1-5.

Claims

CLAIMS:

1. A method of encapsulating a hydrophilic compound (e.g., a hydrophilic polypeptide or a hydrophilic small molecule compound) having at least one net charge in a polymer to form a microparticle, the method comprising contacting the hydrophilic compound with a counter ion of opposite charge to form a ion-pair (IP) complex, and encapsulating the IP complex in the polymer through an emulsion process.

2. The method of claim 1, wherein the IP complex is formed in situ.

3. The method of claim 2, wherein the emulsion process is a w/o/w (water-in-oil-in- water) double emulsion process comprising the steps of:

(a) emulsifying an aqueous phase in a larger volume of an organic phase to form a water-in-oil (w/o) primary emulsion, wherein:

(1) the aqueous phase is formed by dissolving the hydrophilic compound in an aqueous solvent;

(2) the organic phase is formed by dissolving the polymer and the counter ion in an organic solvent; and,

(3) the IP complex forms in situ upon contacting the hydrophilic compound in the aqueous phase with the counter ion in the organic phase;

(b) emulsifying said primary emulsion in a larger volume of an external aqueous phase comprising a surfactant to form the w/o/w double emulsion;

(c) removing organic solvent (e.g., by evaporation); and,

(d) isolating the resulting microparticle.

4. The method of claim 2, wherein the emulsion process is an o/w (oil-in-water) emulsion process comprising the steps of:

(a) emulsifying an organic phase in a larger volume of an aqueous phase to form an oil-in-water (o/w) emulsion, wherein:

(3) the IP complex forms in situ upon contacting the hydrophilic compound in the aqueous phase with the counter ion in the organic phase; (b) removing organic solvent (e.g., by evaporation); and,

(c) isolating the resulting microparticle. The method of claim 1, wherein the IP complex is pre-formed. The method of claim 5, wherein the emulsion process is an o/w (oil-in-water) emulsion process comprising the steps of:

(1) the organic phase is formed by dissolving the polymer and the IP complex in an organic solvent; and,

(2) the IP complex is pre-formed and isolated as a water-insoluble precipitate, by dissolving the hydrophilic compound and the counter ion in an aqueous solvent, or a mixture of the aqueous solvent and a second solvent miscible thereto; and,

(b) removing organic solvent (e.g., by evaporation); and,

(c) isolating the resulting microparticle. The method of any one of claims 1-6, wherein the polymer is a biodegradable polymer selected from: polylactide (PLA) (such as poly(D,L-lactide) or PDLLA, poly(L-lactide) or PLLA, and poly(D-lactide) or PDLA); poly(lactide-co-glycolide) (PLGA); polyhydroxyalkanoate (PHA); polycaprolactone (PCL); and copolymers and mixtures thereof. The method of any one of claims 1-7, wherein the hydrophilic compound is a hydrophilic therapeutic protein or therapeutic peptide. The method of any one of claims 1-8, wherein the hydrophilic compound has one or more positive charge, and the counter ion is an anionic compound selected from: Sodium Dodecyl Sulphate (SDS), dextran sulphate (DS) and salt thereof (such as dextran sulfate sodium salt) optically with an average molecular weight of about 9,000-11,000 Da, 19,000-21,000 Da, 29,000-31,000 Da, 39,000-41,000 Da, or >500,000 Da, docusate or salt thereof (such as sodium salt), fatty acids (e.g., capric acid, or stearic acid), polyacids (e.g., polymerized high molecular weight carbon chain (e.g., alkyl chain) having multiple attached / branched carbpxyl groups), pamoic acid or PA, dioctyl sulfosuccinic acid, phospholipids, bile acids such as cholic acid and deoxycholic, or a mixture thereof. The method of any one of claims 1-8, wherein the hydrophilic compound has one or more negative charge, and the counter ion is a cationic compound selected from: amine-based surfactants, lipids, polymers, and other hydrophobic molecules. The method of any one of claims 3, 4, and 6-10, wherein the organic solvent is chloroform, dichloromethane, ethyl acetate, benzyl alcohol, or a water-miscible solvent (such as alcohol, acetane, DMSO, DMF, THF, and acetonitrile). The method of any one of claims 3, 4, and 6-11, wherein the aqueous solvent is a pH- adjusted water or buffered solution. The method of any one of claims 3 and 7-11, wherein the surfactant is a sorbitan fatty acid ester (such as sorbitan trioleate, polyoxyethylated sorbitan monooleate and other ethoxylated fatty acid esters of sorbitan), a phosphatide (such as lecithin), acacia, tragacanth, a polyoxyalkylene derivative of propylene glycol (such as those available under the trademark PLURONICS, especially PLURONICS F68); a polyoxyethylated fat, a polyoxyethylated oleotriglyceride, a linolizated oleotriglyceride, a polyethylene oxide condensation product of fatty alcohol, an alkylphenol or fatty acid or 1-methyl- 3 -(2-hydroxyethyl)imidazolidone-(2) .

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