WO2021167957A1 - Inorganic coatings for the sustained release of bioactive compounds - Google Patents

Abstract

The disclosure provides a pharmaceutical composition in which a bioactive compound is captured within an inorganic precipitate. Upon administration of the captured bioactive compound to a subject's target tissue, the dissolution of the inorganic precipitate results in the sustained release of the bioactive compound to the site of administration.

Description

INORGANIC COATINGS FOR THE SUSTAINED RELEASE OF BIO ACTIVE

COMPOUNDS

CROSS REFERENCE

This application claims priority to U.S. Provisional Patent Application No. 62/979,056, filed February 20, 2020, which application is herein incorporated by reference in its entirety for all purposes.

BACKGROUND

Synthetic corticosteroids, such as hydrocortisone, cortisone, prednisone and dexamethasone, are a class of anti-inflammatory drugs that are still routinely used to suppress inflammation and adverse immune responses encountered in patients afflicted with a variety of often systemic diseases including psoriasis, lupus, sarcoidosis, rheumatoid arthritis, asthma, allergies, colitis, autoimmune hemolytic anemia, idiopathic thrombocytopenic purpura or as a result of cancer, e.g., leukemia, lymphoma and multiple myeloma. While certainly effective at diminishing immune responses, long term use of oral steroids can have severe side effects such as glaucoma, osteoporosis and an increased risk of metabolic syndrome, which can lead to weight gain, high blood sugar, high blood pressure, heart disease and diabetes.

To avoid the serious caveats associated with systemic administration, steroids are often administered locally via injection or inhalation. For example, the corticosteroids, methylprednisolone and triamcinolone, can be injected intraarticularly to treat inflammation and pain in joints caused by rheumatoid arthritis, osteoarthritis, bursitis, and gout. In other examples, corticosteroids can be injected intraocularly for the treatment of ophthalmologic conditions such as diabetic macular edema, posterior uveitis, and macular edema secondary to vascular occlusions.

However, loading drugs with a high encapsulation efficiency sufficient to ensure a sustained local release of a steroid over long periods of time remains challenging. The difficulties associated with drug delivery are further compounded by burst drug delivery toxicity and potential adverse immune reactions to carrier substances.

SUMMARY

Recognized herein is an unmet need for compositions and methods that provide for a sustained delivery of corticosteroids over a long time period while reducing the frequency of corticosteroid injections and potential complications associated with such injections, such as infections and tissue damage. Such compositions and methods can be especially useful in use of corticosteroids to treat chronic conditions.

The present disclosure meets this need by capturing a bioactive compound within an inorganic, bioresorbable, nanoporous precipitate. The captured bioactive compound coated with the inorganic precipitate can then be administered via injection to a subject in need thereof. The gradual disintegration of the coating of inorganic precipitate in vivo results in the controlled and sustained release of the bioactive compound from the inorganic precipitate to the extracellular space at the site of administration. The bioactive compound can be water-insoluble corticosteroid crystals that are coated in a mineral deposit that facilitates the controlled and sustained delivery of the corticosteroid upon its injection into a target tissue.

In a first aspect, a pharmaceutical composition for sustaining the release of a bioactive compound to a subject in need thereof is disclosed comprising a bioactive compound captured within an inorganic precipitate, wherein, upon administration to a subject, the inorganic precipitate is effective at sustaining the extracellular delivery of the bioactive compound to a site of administration.

In some embodiments of the first aspect, the composition does not contain a polymer.

In some embodiments of the first aspect, the composition does not contain a glass or metal particle or bead.

In some embodiments of the first aspect, the inorganic precipitate is effective at sustaining the extracellular release of the bioactive compound to a site of administration for 10-90 days.

In some embodiments of the first aspect, the inorganic precipitate comprises a ceramic.

In some embodiments of the first aspect, the inorganic precipitate comprises calcium and phosphate ions in a molar ratio of from about 10: 1 to about 1:10.

In some embodiments of the first aspect, the inorganic precipitate comprises carbonate and phosphate ions in a molar ratio from about 10:1 to about 1:10.

In some embodiments of the first aspect, the bioactive compound comprises a small molecule, a protein or a nucleic acid.

In some embodiments of the first aspect, the small molecule comprises a steroid chosen from a corticosteroid, a glucocorticoid, a mineralocorticoid, an anabolic steroid or a sex steroid.

In some embodiments of the first aspect, the steroid comprises a Class A, Class B, Class C or Class D corticosteroid. In some embodiments of the first aspect, the Class A corticosteroid is chosen from hydrocortisone acetate, methylprednisolone, prednisolone, cloprednol, fludrocortisone acetate, or pharmaceutical equivalents thereof; the Class B corticosteroid is chosen from amcinonide, desonide, fluocinolone acetonide, halcinonide, triamcinolone acetonide or diacetate, budesonide, or pharmaceutical equivalents thereof; the Class C corticosteroid is chosen from clocortolone pivalate, desoximetasone, betamethasone, dexamethasone, or pharmaceutical equivalents thereof, and the Class D corticosteroid is chosen from alclometasone dipropionate, betamethasone dipropionate, betamethasone valerate, clobetasol propionate, clobetasone butyrate, diflorasone diacetate, fluticasone propionate, mometasone furoate, or pharmaceutical equivalents thereof.

In a second aspect, a method for preparing a sustained release pharmaceutical composition is disclosed comprising adding an inorganic metal salt solution to a bioactive compound, wherein the inorganic metal salt solution forms an inorganic precipitate that captures the bioactive compound.

In some embodiments of the second aspect, the metal salt solution comprises from about 4 mM to about 250 mM NaHCCb.

In some embodiments of the second aspect, the metal salt solution comprises phosphate, carbonate and sulfate anions.

In some embodiments of the second aspect, the alkali metal salts comprise sodium and potassium cations.

In some embodiments of the second aspect, the alkaline earth metal salts comprise calcium and magnesium cations.

In some embodiments of the second aspect, the composition does not contain a polymer or lipid.

In some embodiments of the second aspect, the composition does not contain glass or metal beads or particles.

In some embodiments of the second aspect, the inorganic precipitate comprises a ceramic.

In some embodiments of the second aspect, the inorganic precipitate comprises an oxide.

In a third aspect, a method for sustaining the extracellular delivery of a bioactive compound to a target tissue of a subject in need thereof is disclosed comprising capturing a bioactive compound within an inorganic precipitate, and administering the captured bioactive compound to a target tissue, wherein gradual dissolution of the inorganic precipitate sustains the extracellular delivery of the bioactive compound to the tissue.

In some embodiments of the third aspect, the inorganic precipitate comprises a ceramic.

In some embodiments of the third aspect, the inorganic precipitate comprises an oxide.

In some embodiments of the third aspect, the extracellular delivery of the bioactive compound to the tissue is sustained for 10-90 days.

In some embodiments of the third aspect, the bioactive compound is a steroid.

In some embodiments of the third aspect, the subject’s tissue is an osteoarthritic joint.

Additional aspects and advantages of the present disclosure will become readily apparent to those skilled in this art from the following detailed description, wherein only illustrative embodiments of the present disclosure are shown and described. As will be realized, the present disclosure is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. To the extent publications and patents or patent applications incorporated by reference contradict the disclosure contained in the specification, the specification is intended to supersede and/or take precedence over any such contradictory material.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings (also “Figure” and “FIG.” herein), of which:

FIG. 1 shows an example solubility chart of ionic compounds;

FIG. 2 shows example SEM images of mineral coated corticosteroids; FIG. 3A shows example mineral coated methylprednisolone; and

FIG. 3B depicts an example graph showing a reduced release rate of methylprednisolone from a mineral coated composition.

DETAILED DESCRIPTION

While various embodiments of the invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions may occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed.

Definitions

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 disclosure herein belongs.

As used herein, the singular forms “a,” “an,” and “the,” are intended to include the plural forms as well, unless the context clearly indicates otherwise.

The phrase “and/or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, e.g., elements that are conjunctively present in some cases and disjunctively present in other cases. Thus, as a non limiting example, a reference to “A and/or B”, when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.

As used herein in the specification and in the claims, the phrase “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, “at least one of A and B” (or, equivalently, “at least one of A or B,” or, equivalently “at least one of A and/or B”) can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc.

In some embodiments, the term "about" or "approximately" as used herein means within an acceptable error range for the particular value, which will depend in part on how the value is measured or determined, e.g., the limitations of the measurement system. In some embodiments, "about" can mean within 3 or more than 3 standard deviations, per the practice in the art. In some embodiments, the term can mean within an order of magnitude, such as, for example, within 5 - fold, or within 2-fold, of a value.

In some embodiments, when the term “about” or “approximately” is used in conjunction with a numerical range, it modifies that range by extending the boundaries above and below those numerical values. In general, the term “about” is used herein to modify a numerical value above and below the stated value by a variance of 20%, 10%, 5%, or 1%. In some embodiments, the term “about” is used to modify a numerical value above and below the stated value by a variance of 10%. In some embodiments, the term “about” is used to modify a numerical value above and below the stated value by a variance of 5%. In some embodiments, the term “about” is used to modify a numerical value above and below the stated value by a variance of 1%.

When a range of values is listed herein, it is intended to encompass each value and sub range within that range. For example, “1-5 ng” or “from about 1 ng to about 5 ng” is intended to encompass 1 ng, 2 ng, 3 ng, 4 ng, 5 ng, 1-2 ng, 1-3 ng, 1-4 ng, 1-5 ng, 2-3 ng, 2-4 ng, 2-5 ng, 3-4 ng, 3-5 ng, and 4-5 ng.

It will be further understood that the terms “comprises,” “comprising,” “includes,” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

As used herein, the term “administering,” refers to the placement of the bioactive compound captured within the inorganic precipitate as disclosed herein into a subject by a method or route which results in at least partial delivery of the composition at a given extracellular location of a target tissue. In some embodiments, the bioactive compound captured within the inorganic precipitate can be, for example, injected into a subject in need thereof by either intra-dermal, intra muscular, subcutaneous, intra-articular, peri-articular or intravenous administration. In some embodiments, the bioactive compound captured within the inorganic precipitate administered parenterally, e.g., by intravenous, intra-arterial, intracardiac, intraspinal, intraosseous, intra- articular, intra-synovial, subcutaneous, intradermal, intra-tendinous, intra-ligamentous or intramuscular administration. In some embodiments, the bioactive compound captured within the inorganic precipitate is administered by implantation, infiltration or infusion.

"Effective amount" or "therapeutically effective amount" means a dosage sufficient to alleviate one or more symptoms of the condition being treated, or to otherwise provide a suitable pharmacological and/or physiologic effect, as may be determined by an objective measure or a patient derived subjective measure. In some embodiments, an “effective amount” refers to the optimal amount of a bioactive compound captured within the inorganic precipitate needed to elicit a clinically significant improvement in the symptoms and/or pathological state associated with a disorder to be treated. The therapeutically effective amount can vary depending upon the intended application or the subject and disease condition being treated, e.g., the weight and age of the subject, the severity of the disease condition, the manner of administration and the like.

As used herein, the terms “treat,” “treatment,” “treating” refer to therapeutic treatments, wherein the object is to reverse, alleviate, ameliorate, inhibit, slow down or stop the progression or severity of a disorder. The term “treating” includes reducing or alleviating at least one adverse effect or symptom of a condition, disease or disorder. Treatment is generally “effective” if one or more symptoms or clinical markers are reduced. Alternatively, treatment is “effective” if the progression of a disorder is reduced or halted. That is, “treatment” includes not just the improvement of symptoms or markers, but also a cessation of, or at least slowing of, progress or worsening of symptoms compared to those in the absence of treatment. Beneficial clinical results include, but are not limited to, alleviation of one or more symptom(s), diminishment of extent of disease, stabilized (e.g., not worsening) state of disease, delay or slowing of disease progression, amelioration or palliation of the disease state, remission (whether partial or total), and/or decreased mortality, whether detectable or undetectable. The term “treatment” of a disease also includes providing relief from the symptoms or side-effects of the disease (including palliative treatment).

As used herein, the term “tissue” or “target tissue” refers to an aggregation of morphologically similar cells and associated intercellular matter, e.g., extracellular matrix, acting together to perform one or more specific functions in the body. In some embodiments, tissues fall into one of four basic types: muscle, nerve, epidermal, and connective. In some embodiments, a tissue is substantially solid, e.g., cells within the tissue are strongly associated with one another to form a multicellular solid tissue. In some embodiments, a tissue is substantially non-solid, e.g., cells within the tissue are loosely associated with one another, or not at all physically associated with one another, but may be found in the same space, bodily fluid, etc. For example, blood cells are considered a tissue in non-solid form. In some embodiments, a tissue comprises a joint such as a knee joint having a synovial cavity /joint filled with synovial fluid and synoviocytes. In some embodiments, the tissue may be an osteoarthritic joint.

As used herein, a ceramic can be neither metallic nor organic material that can be crystalline, glassy or both crystalline and glassy. In some embodiments, ceramics can be hard and chemically non-reactive and can be formed or densified with heat.

As used herein, the term “extracellular” means being situated or taking place outside a cell or cells.

A “subject” refers to a vertebrate, with non-limiting examples that include a mammal (e.g., a non-human mammal), a primate and a human. Mammals include, but are not limited to, primates, humans, farm animals, rodents, sport animals, and pets.

Example polymers

In some embodiments, an inorganic precipitate does not contain a polymer, e.g. a natural polymer or a synthetic polymer.

Example polymers include, but are not limited to, poly(lactic acid), derivatives of poly(lactic acid), PEGylated poly(lactic acid), poly(lactic-co-glycolic acid), derivatives of poly(lactic-co-glycolic acid), PEGylated poly(lactic-co-gly colic acid), polyanhydrides, poly(ortho esters) derivatives of pholy(ortho esters), PEGylated poly(ortho esters), poly(caprolactones), derivatives of poly(caprolactone), PEGylated poly(caprolactone), polylysine, derivatives of polylysine, PEGylated polylysine, polyethylene imine), derivatives of poly(ethylene imine), PEGylated poly(ethylene imine), poly(acrylic acid), derivatives of poly(acrylic acid), poly(urethane), derivatives of poly(urethane), and combinations thereof.

Example synthetic polymers include polyanhydrides, polyhydroxyacids such as polylactic acid, polyglycolic acids and copolymers thereof, polyesters, polyamides, polyorthoesters, and some polyphosphazenes.

Example naturally occurring polymers include proteins and polysaccharides such as collagen, hyaluronic acid, albumin and gelatin. U.S. Patents that describe the use of polyanhydrides for controlled delivery of substances include U.S. Pat. No. 4,857,311 to Domb and Langer, U.S. Pat. No. 4,888, 176 to Langer, etak, and U.S. Pat. No. 4,789,724 to Domb andLanger, the contents of which are incorporated by reference herein in their entireties. Example Bioactive compounds

A “bioactive” composition, substance, or agent is a composition that affects a biological function of a subject to which it is administered. An example of a bioactive composition is a pharmaceutical substance, such as a drug or antibiotic, which is given to a subject to alter a physiological condition of the subject such as a disease. Bioactive substances, compositions, agents and compounds also include other biomolecules, such as proteins and nucleic acids. Bioactive compositions also may include pharmaceutical carriers, adjuvants, and salts.

In some embodiments, a "bioactive compound" or “active pharmaceutical ingredient” (API) or “pharmaceutical” are used interchangeably and refer to a drug or pro-drug, including those which can be used for the treatment or prophylaxis of a disorder in a mammal, such as a human.

In some embodiments, a “bioactive compound” includes, but is not limited to, a pharmaceutically acceptable polypeptide, protein or nucleic acid or small molecule. In some embodiments, the nucleic acid comprises, for example, DNA, RNA, modified DNA, modified RNA, mRNA, RNAi or miRNA.

In some embodiments, the polypeptide can comprise at least 1 amino acid, at least 10 amino acids, at least 25 amino acids, at least 50 amino acids, at least 75 amino acids, at least 100 amino acids, at least 200 amino acids, at least 300 amino acids, at least 400 amino acids or at least 500 amino acids. In some embodiments, a “bioactive compound” can be, for example, a monoclonal antibody or derivative thereof.

In some embodiments, a bioactive compound can be an insoluble solid. In some embodiments, the bioactive compound can be in the form of crystals. In some embodiments, the bioactive compound can be an amorphous solid.

In some embodiments, the small molecule comprises a steroid can be any type of steroid including sex hormones, corticosteroids, glucocorticoids, mineralocorticoids, and anabolic steroids. Sex hormone steroids that can be used include androgens, androstenediol, androstenedione, dehydroepiandrosterone, dihydrotestosterone, testosterone, estrogens, estradiol, estriol, estrone, progestogens, progesterone, or pharmaceutical equivalents thereof. Corticosteroids that can be used include Class A corticosteroids (including hydrocortisone acetate, methylprednisolone, prednisolone, cloprednol, fludrocortisone acetate, and pharmaceutical equivalents thereof), Class B corticosteroids (including amcinonide, desonide, fluocinolone acetonide, halcinonide, triamcinolone acetonide or diacetate, budesonide, or pharmaceutical equivalents thereof), Class C corticosteroids (including clocortolone pivalate, desoximetasone, betamethasone, dexamethasone, or pharmaceutical equivalents thereof), or Class D corticosteroids (including alclometasone dipropionate, betamethasone dipropionate, betamethasone valerate, clobetasol propionate, clobetasone butyrate, diflorasone diacetate, fluticasone propionate, mometasone furoate, or pharmaceutical equivalents thereof). The steroid can be isolated from biological material or synthesized.

"Pharmaceutically acceptable" refers to molecular entities and compositions that are "generally regarded as safe" - e.g., that are physiologically tolerable and do not typically produce an allergic or similar untoward reaction, such as gastric upset and the like, when administered to a human. In some embodiments, this term refers to molecular entities and compositions approved by a regulatory agency of the Federal or a State government, e.g., the GRAS list under section 204(s) and 409 of the Federal Food, Drug and Cosmetic Act, that is subject to premarket review and approval by the FDA or similar lists, the U.S. Pharmacopeia or another generally recognized pharmacopeia for use in animals and humans.

Example Inorganic Metal Salt Solutions

Mineral coatings can be created by incubating water-insoluble corticosteroids in an example inorganic metal salt solution. In some embodiments, an example inorganic metal salt solution may be a modified simulated body fluid (mSBF), which contains ionic constituents and concentrations that are comparable to human plasma. In some embodiments, an example inorganic metal salt solution may be a modified simulated body fluid (mSBF), which contains ionic constituents and concentrations that are comparable to human plasma except the concentration of calcium and phosphate ions is doubled.

In some embodiments, an example inorganic metal salt solution comprises at least two alkali metal salts (Group I), for example, lithium, sodium and potassium cations.

In some embodiments, an example inorganic metal salt solution may comprise about 250- 225mM, 250-200mM, 250-175mM, 250-150mM, 250-125mM, 250-100mM, 250-75mM, 250- 50mM, 250-25mM or 250-lmM sodium cations.

In some embodiments, an example inorganic metal salt solution may comprise about 250- lmM, 225-lmM, 200-lmM, 175-lmM, 150-lmM, 125-lmM, 100-lmM, 75-lmM, 50-lmM or 25-lmM Na ions.

In some embodiments, an example inorganic metal salt solution may comprise about 141mM sodium cations. In some embodiments, an example inorganic metal salt solution may comprise about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 or 25mM potassium cations.

In some embodiments, an example inorganic metal salt solution may comprise about 4mM potassium cations.

In some embodiments, an example inorganic metal salt solution may comprise about 4mM

KC1.

In some embodiments, an example inorganic metal salt solution may comprise about 2 mM KH2PO4.

In some embodiments, the inorganic metal salt solution comprises at least two alkaline earth metal salts (Group II), for example, calcium, magnesium cations, barium and strontium.

In some embodiments, an example inorganic metal salt solution may comprise about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 or 25mM magnesium cations.

In some embodiments, an example inorganic metal salt solution may comprise about 0.5mM magnesium cations.

In some embodiments, an example inorganic metal salt solution may comprise about 0.5mM MgSCU.

In some embodiments, an example inorganic metal salt solution may comprise about ImM

MgCk.

In some embodiments, an example inorganic metal salt solution may comprise about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 or 25mM calcium cations.

In some embodiments, an example inorganic metal salt solution may comprise from 1- 25mM, 2-25mM, 3-25mM, 4-25mM, 5-25mM, 6-25mM, 7-25mM, 8-25mM, 9-25mM, 10-25mM, 1 l-25mM, 12-25mM, 13-25mM, 14-25mM, 15-25mM, 16-25mM, 17-25mM, 18-25mM, 19- 25mM, 20-25mM, 21-25mM, 22-25mM, 23-25mM, 24-25mM calcium cations.

In some embodiments, an example inorganic metal salt solution may comprise from 1- 25mM, l-24mM, l-23mM, l-22mM, l-21mM, l-20mM, l-19mM, l-18mM, l-17mM, l-16mM, 1-17mM, 1-16mM, l-15mM, l-14mM, l-13mM, l-12mM, 1-1 ImM, 1-lOmM, l-9mM, l-8mM, l-7mM, l-6mM, l-5mM, l-4mM, l-3mM or l-2mM calcium cations. In some embodiments, an example inorganic metal salt solution may comprise less than 25mM calcium cations.

In some embodiments, an example inorganic metal salt solution may comprise about 5mM calcium cations.

In some embodiments, an example inorganic metal salt solution may comprise about 5mM

CaCh.

In some embodiments, the inorganic metal salt solution comprises at least one of phosphate, carbonate and sulfate anions.

In some embodiments, the inorganic metal salt solution comprises at least two of phosphate, carbonate and sulfate anions.

In some embodiments, the inorganic metal salt solution comprises phosphate, carbonate and sulfate anions.

In some embodiments, an example inorganic metal salt solution may comprise from 1- 25mM, 2-25mM, 3-25mM, 4-25mM, 5-25mM, 6-25mM, 7-25mM, 8-25mM, 9-25mM, 10-25mM, 1 l-25mM, 12-25mM, 13-25mM, 14-25mM, 15-25mM, 16-25mM, 17-25mM, 18-25mM, 19- 25mM, 20-25mM, 21-25mM, 22-25mM, 23-25mM, 24-25mM phosphate anions.

In some embodiments, an example inorganic metal salt solution may comprise about 1- 25mM, l-24mM, l-23mM, l-22mM, l-21mM, l-20mM, l-19mM, l-18mM, l-17mM, l-16mM, 1-17mM, 1-16mM, l-15mM, l-14mM, l-13mM, l-12mM, 1-1 ImM, 1-lOmM, l-9mM, l-8mM, l-7mM, l-6mM, l-5mM, l-4mM, l-3mM or l-2mM phosphate anions.

In some embodiments, an example inorganic metal salt solution may comprise about 2mM phosphate anions.

In some embodiments, an example inorganic metal salt solution may comprise about 0.25- 25mM, 0.5-25mM, 0.75-25mM, l-25mM, 2-25mM, 3-25mM, 4-25mM, 5-25mM, 6-25mM, 7- 25mM, 8-25mM, 9-25mM, 10-25mM, l l-25mM, 12-25mM, 13-25mM, 14-25mM, 15-25mM, 16- 25mM, 17-25mM, 18-25mM, 19-25mM, 20-25mM, 21-25mM, 22-25mM, 23-25mM, 24-25mM sulfate anions.

In some embodiments, an example inorganic metal salt solution may comprise about 0.25- 25mM, 0.25-24mM, 0.25-23mM, 0.25-22mM, 0.25-21mM, 0.25-20mM, 0.25-19mM, 0.25- 18mM, 0.25-17mM, 0.25-16mM, 0.25-17mM, 0.25-16mM, 0.25-15mM, 0.25-14mM, 0.25- 13mM, 0.25-12mM, 0.25-1 ImM, 0.25-10mM, 0.25-9mM, 0.25-8mM, 0.25-7mM, 0.25-6mM, 0.25-5mM, 0.25-4mM, 0.25-3mM or 0.25-2mM sulfate anions.

In some embodiments, an example inorganic metal salt solution may comprise about 0.5mM sulfate anions.

In some embodiments, an example inorganic metal salt solution may comprise about 0.25- 25mM, 0.5-25mM, 0.75-25mM, l-25mM, 2-25mM, 3-25mM, 4-25mM, 5-25mM, 6-25mM, 7- 25mM, 8-25mM, 9-25mM, 10-25mM, ll-25mM, 12-25mM, 13-25mM, 14-25mM, 15-25mM, 16- 25mM, 17-25mM, 18-25mM, 19-25mM, 20-25mM, 21-25mM, 22-25mM, 23-25mM, 24-25mM carbonate anions.

In some embodiments, an example inorganic metal salt solution may comprise about 0.25- 25mM, 0.25-24mM, 0.25-23mM, 0.25-22mM, 0.25-21mM, 0.25-20mM, 0.25-19mM, 0.25- 18mM, 0.25-17mM, 0.25-16mM, 0.25-17mM, 0.25-16mM, 0.25-15mM, 0.25-14mM, 0.25- 13mM, 0.25-12mM, 0.25-1 ImM, 0.25-10mM, 0.25-9mM, 0.25-8mM, 0.25-7mM, 0.25-6mM, 0.25-5mM, 0.25-4mM, 0.25-3mM, 0.25-2mM or 0.25-lmM carbonate anions.

In some embodiments, an example inorganic metal salt solution may comprise about 4.2mM carbonate anions.

In some embodiments, an example inorganic metal salt solution may comprise about 0.25- 25mM, 0.5-25mM, 0.75-25mM, l-25mM, 2-25mM, 3-25mM, 4-25mM, 5-25mM, 6-25mM, 7- 25mM, 8-25mM, 9-25mM, 10-25mM, ll-25mM, 12-25mM, 13-25mM, 14-25mM, 15-25mM, 16- 25mM, 17-25mM, 18-25mM, 19-25mM, 20-25mM, 21-25mM, 22-25mM, 23-25mM, 24-25mM NaHC0_3.

In some embodiments, an example inorganic metal salt solution may comprise about 0.25- 25mM, 0.25-24mM, 0.25-23mM, 0.25-22mM, 0.25-21mM, 0.25-20mM, 0.25-19mM, 0.25- 18mM, 0.25-17mM, 0.25-16mM, 0.25-17mM, 0.25-16mM, 0.25-15mM, 0.25-14mM, 0.25- 13mM, 0.25-12mM, 0.25-1 ImM, 0.25-10mM, 0.25-9mM, 0.25-8mM, 0.25-7mM, 0.25-6mM, 0.25-5mM, 0.25-4mM, 0.25-3mM, 0.25-2mM or 0.25-lmM NaHCOs.

In some embodiments, an example inorganic metal salt solution may comprise about 250- 225mM, 250-200mM, 250-175mM, 250-150mM, 250-125mM, 250-100mM, 250-75mM, 250- 50mM, 250-25mM or 250-lmM NaHC0_3.

In some embodiments, an example inorganic metal salt solution may comprise about 250- lmM, 225-lmM, 200-lmM, 175-lmM, 150-lmM, 125-lmM, 100-lmM, 75-lmM, 50-lmM or 25-lmM NaHC0_3. In some embodiments, an example inorganic metal salt solution may comprise about 4.2- 250mM NaHCCh.

In some embodiments, an example inorganic metal salt solution may comprise about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 or 25mM NaHC0₃.

In some embodiments, an example inorganic metal salt solution may comprise about 4.2mM NaHCCh.

In some embodiments, an example inorganic metal salt solution may have a molar ratio of calcium to phosphate ions from about 10: 1 to about 1:10.

In some embodiments, an example inorganic metal salt solution may have a molar ratio of calcium to phosphate ions from about 10: 1 to about 1:10, from about 9: 1 to about 1:10, from about 8:1 to about 1:10, from about 7:1 to about 1:10, from about 6:1 to about 1:10, from about 5:1 to about 1:10, from about 4:1 to about 1:10, from about 3:1 to about 1:10, from about 2:1 to about 1:10, from about 1 : 1 to about 1:10.

In some embodiments, an example inorganic metal salt solution may have a molar ratio of calcium to phosphate ions from about 10:1 to about 1:9, from about 10:1 to about 1:8, from about 10:1 to about 1:7, from about 10:1 to about 1:6, from about 10:1 to about 1 :5, from about 10:1 to about 1:4, from about 10: 1 to about 1:3, from about 10:1 to about 1:2 or from about 10:1 to about 1:1.

In some embodiments, an example inorganic metal salt solution may have a molar ratio of carbonate and phosphate ions from about 10:1 to about 1:1.

In some embodiments, an example inorganic metal salt solution may have a molar ratio of carbonate and phosphate ions from about 10:1 to about 1:10, from about 9:1 to about 1:10, from about 8:1 to about 1:10, from about 7:1 to about 1:10, from about 6:1 to about 1:10, from about 5:1 to about 1:10, from about 4:1 to about 1:10, from about 3:1 to about 1:10, from about 2:1 to about 1:10, from about 1 : 1 to about 1:10.

In some embodiments, an example inorganic metal salt solution may have a molar ratio of carbonate and phosphate ions from about 10:1 to about 1:9, from about 10:1 to about 1:8, from about 10:1 to about 1:7, from about 10:1 to about 1:6, from about 10:1 to about 1:5, from about 10:1 to about 1:4, from about 10:1 to about 1:3, from about 10:1 to about 1 :2 or from about 10:1 to about 1:1. In some embodiments, an example inorganic metal salt solution may comprise 141 mM NaCl, 4 mM KC1, 0.5 mM MgS0₄, 1 mM MgCk, 5 mM CaCh, 2 mM KH₂P0₄, and 4.2 mM NaHCCb that is buffered to a pH of 6.8.

In some embodiments, ionic buffers that may be used in the example inorganic metal salt solution may be, for example, phosphate buffers, sodium chloride buffers, magnesium chloride buffers, calcium chloride buffers, sodium fluoride buffers, and combinations thereof. Suitable pH ionic buffers may have a pH range of from about 6.4 to about 7.8.

Example Inorganic Precipitates

In some embodiments, the cations and anions of the inorganic metal salt solution react to form an inorganic insoluble precipitate.

In some embodiments, an example inorganic metal salt solution may be incubated with a bioactive compound for 1-10, 1-20, 1-30, 1-40, 1-50, 1-60, 1-70, 1-80, 1-90, 1-100, 1-110 or 1- 120 minutes.

In some embodiments, an example inorganic metal salt solution may be incubated with a bioactive compound for 1-120, 10-120, 20-120, 30-120, 40-120, 50-120, 60-120, 70-120, 80-120, 90-120, 100-120 or 110-120 minutes.

In some embodiments, an example inorganic metal salt solution may be incubated with a bioactive compound for 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23 or 24 hours.

In some embodiments, an example inorganic metal salt solution may be incubated with a bioactive compound for about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 or 14 days.

In some embodiments, an example inorganic metal salt solution may be incubated with a bioactive compound for about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12 weeks.

In some embodiments, an example inorganic metal salt solution may be incubated with a bioactive compound at about 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39 or 40 degrees Celsius.

In some embodiments, the inorganic precipitate comprises at least one of calcium carbonate, calcium phosphate and magnesium carbonate.

In some embodiments, the inorganic precipitate comprises at least two of calcium carbonate, calcium phosphate and magnesium carbonate. In some embodiments, the inorganic precipitate comprises calcium carbonate, calcium phosphate and magnesium carbonate.

In some embodiments, the inorganic precipitate is bioresorbable and nanoporous.

In some embodiments, the composition comprising the inorganic precipitate does not comprise a polymer as defined herein.

In some embodiments, the composition comprising the inorganic precipitate does not comprise glass or metal bead or particle.

In some embodiments, the composition comprising the inorganic precipitate comprises a ceramic.

In some embodiments, the composition comprises inorganic precipitates having a diameter of about 0.01-10 pm.

In some embodiments, the surface of the inorganic precipitates can be very rough and can comprise a large number of nanometer-sized pores and channels. The specific morphology facilitates the capture of bioactive compounds which can permeate into the particles of precipitate, or by the affinity to the carbonate surface, enabling very high substrate loading.

In some embodiments, the phosphate/carbonate ratio is important for the dissolution kinetics of the inorganic precipitate. In some embodiments, the addition of more carbonate produces an inorganic precipitate having a faster dissolution in vivo.

Example Administration of Mineral Coated Bioactive Compound

In some embodiments, the inorganic precipitate described herein forms a bioresorbable, nano-porous mineral coatings on a water-insoluble particulate bioactive compound such as a corticosteroid that may be administered to a target tissue in need of treatment. The mineral coatings have compositional and morphological features to human bone, and therefore they are bioresorbable and biocompatible. In addition, they have a generic affinity to a broad range of bioactive compounds including proteins. Without being bound to a specific mechanism of action, insoluble corticosteroids can become soluble and active by esterases when injected. The mineral coatings form a physical barrier that slows down the release of corticosteroids in two ways. First, the presence of highly porous coating on the corticosteroid particulates can extend the pathway for esterases to travel to get in contact with the corticosteroids and for corticosteroids solubilized by esterases to escape the coating layer. Second, the high affinity of proteins to the mineral coatings can delay the penetration of esterases and thus corticosteroid solubilization. In some embodiments, two or more different populations of mineral coated bioactive compounds can be administered to a target tissue. Each population may comprise a different bioactive compound or a mixture of different bioactive compounds. In some embodiments, each population may have different mineral coatings that have different disintegration rates in vivo.

EXAMPLES

EXAMPLE 1: PREPARATION OF MINERAL-COATED CORTICOSTEROIDS

Mineral coatings were prepared on water-insoluble corticosteroid powders (triamcinolone acetonide, triamcinolone hexacetonide or methylprednisolone acetate) by incubating in mSBF. Briefly, corticosteroids powders were added to mSBF at a ratio of 2 mg powder per mL mSBF, and then incubated at 37oC under rotation for one or two weeks. The mSBF was replenished daily by centrifuging, discarding supernatant, and adding fresh mBSF. At the completion of incubation in mSBF, the resulting particles were rinsed twice with deionized water and lyophilized. The SEM images showed that the mineral coatings can be created on the corticosteroids (see FIG. 2). Although 1-week incubation in mSBF resulted in incomplete coating formation, mineral coatings can be uniformly formed after 2-week mSBF incubation. The coating was nanoporous, and its morphology was similar to mineral coatings created by the incubation in mSBF.

EXAMPLE 2: METHYLPREDNISOLONE ACETATE RELEASE FROM

MINERAL-COATED METHYLPREDNISOLONE ACETATE

Methylprednisolone release from mineral-coated methylprednisolone acetate was quantified. Briefly, methylprednisolone acetate or mineral-coated methylprednisolone acetate (5 mg) was added to simulated body fluid (SBF, 1 mL, supplemented with 0.05 w/v% sodium azide) in microcentrifuge tubes, and then incubated at 37°C under rotation. At the predetermined time points, the tubes were centrifuged at 1000 ref for 5 minutes and the supernatants were collected and frozen at -20°C until assayed. The remaining pellets were resuspended in SBF (1 mL, supplemented with 0.05 w/v % sodium azide) and the incubation was continued. Example SEM imaging of the mineral-coated methylprednisolone acetate are depicted in FIG. 3A. The collected supernatants were used to quantify the amount of released methylprednisolone by measuring UV absorbance at 260 nm. The water-soluble methylprednisolone hydrogen succinate was used to create a standard curve is shown in FIG. 3B. The release rate of methylprednisolone was significantly reduced by the presence of mineral coating. For example, 24.12 pg methylprednisolone/mg particle was released from mineral-coated methylprednisolone acetate for 32 days whereas methylprednisolone acetate released 106.56 pg/mg particle during the same time period. Both methylprednisolone acetate and mineral-coated methylprednisolone acetate showed linear release kinetics for up to 88 days.

While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. It is not intended that the invention be limited by the specific examples provided within the specification. While the invention has been described with reference to the aforementioned specification, the descriptions and illustrations of the embodiments herein are not meant to be construed in a limiting sense. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. Furthermore, it shall be understood that all aspects of the invention are not limited to the specific depictions, configurations or relative proportions set forth herein which depend upon a variety of conditions and variables. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is therefore contemplated that the invention shall also cover any such alternatives, modifications, variations or equivalents. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.

Claims

CLAIMS What is claimed is:

1. A pharmaceutical composition for sustained release of a bioactive compound to a subject in need thereof, comprising a bioactive compound captured within an inorganic precipitate, wherein, upon administration to the subject in need thereof, the inorganic precipitate is effective at sustaining the extracellular release of the bioactive compound to a site of administration.

2. The pharmaceutical composition of claim 1, wherein the composition does not contain a polymer.

3. The pharmaceutical composition of claim 2, wherein the composition does not contain a glass or metal particle or bead.

4. The pharmaceutical composition of claim 3, wherein the inorganic precipitate comprises a ceramic.

5. The pharmaceutical composition of claim 4, wherein the ceramic is amorphous or partially amorphous.

6. The pharmaceutical composition of claim 3, wherein the inorganic precipitate is effective at sustaining the extracellular release of the bioactive compound to a site of administration for 10-90 days.

7. The pharmaceutical composition of claim 3, wherein the inorganic precipitate comprises calcium and phosphate ions in a molar ratio of from about 10: 1 to about 1:10.

8. The pharmaceutical composition of claim 3, wherein the inorganic precipitate comprises carbonate and phosphate ions in a molar ratio from about 10: 1 to about 1:10.

9. The pharmaceutical composition of claim 3, wherein the bioactive compound comprises a small molecule, a protein or a nucleic acid.

10. The pharmaceutical composition of claim 9, wherein the small molecule comprises a steroid chosen from a corticosteroid, a glucocorticoid, a mineralocorticoid, an anabolic steroid or a sex steroid.

11. The pharmaceutical composition of claim 10, wherein the corticosteroid comprises a Class A, Class B, Class C or Class D corticosteroid.

12. The pharmaceutical composition of claim 11, wherein

• the Class A corticosteroid is hydrocortisone acetate, methylprednisolone, prednisolone, cloprednol, fludrocortisone acetate, or a pharmaceutical equivalent thereof;

• the Class B corticosteroid is amcinonide, desonide, fluocinolone acetonide, halcinonide, triamcinolone acetonide or diacetate, budesonide, or a pharmaceutical equivalent thereof;

• the Class C corticosteroid is clocortolone pivalate, desoximetasone, betamethasone, dexamethasone, or a pharmaceutical equivalents thereof, and

• the Class D corticosteroid is alclometasone dipropionate, betamethasone dipropionate, betamethasone valerate, clobetasol propionate, clobetasone butyrate, diflorasone diacetate, fluticasone propionate, mometasone furoate, or a pharmaceutical equivalent thereof.

13. A method for preparing a sustained release pharmaceutical composition, comprising adding an inorganic metal salt solution to a bioactive compound, wherein the inorganic metal salt solution forms an inorganic precipitate that captures the bioactive compound.

14. The method of claim 13, wherein the metal salt solution comprises sodium, potassium, calcium and magnesium cations.

15. The method of claim 14, wherein the metal salt solution further comprises phosphate, carbonate and sulfate anions.

16. A method for sustained extracellular delivery of a bioactive compound to a target tissue of a subject in need thereof, comprising capturing a bioactive compound within an inorganic precipitate, and administering the captured bioactive compound to the target tissue, wherein gradual dissolution of the inorganic precipitate sustains the extracellular delivery of the bioactive compound to the tissue.

17. The method of claim 16, wherein the inorganic precipitate comprises a ceramic.

18. The method of claim 16, wherein the sustained extracellular delivery of the bioactive compound to the target tissue is sustained for 10-90 days.

19. The method of claim 16, wherein the bioactive compound is a corticosteroid.

20. The method of claim 16, wherein the target tissue is an osteoarthritic joint.