HK1036579B - Liquid polymeric compositions for controlled release of bioactive substances - Google Patents

Description

Liquid polymer composition for controlled release of biologically active substances

Technical Field

The present invention relates to liquid polymer compositions; such compositions, e.g. liquid polymer compositions, for example, for the controlled release of at least one biologically active substance, e.g. at least one hydrophobic biologically active substance, may for example form a film-sealing liquid in situ and/or may achieve a long-term sustained release, e.g. a high potency plasma profile (an efficiency above about 70%, such as at least about 80%, preferably at least about 90%, e.g. about 100%, over more than about 12 months) and/or a plasma level for at least about 50 or about 60 days or at least about 2 months or at least about 8 weeks, e.g. at least about 90 days or about 3 months or about 12 weeks or at least about 120 days or about 4 months or about 16 weeks, or at least about 150 days or about 5 months or about 20 weeks, or longer, e.g. at most about 1 year or longer, e.g. 1 to 12 months, in a patient or subject (e.g. an animal or human).

The present invention further relates to a liquid polymer composition comprising: (1) about 1-30% w/v bioactive agent (e.g., hydrophobic bioactive agent); (2) about 1-20% w/v of a biocompatible "polymer" (including "copolymers", i.e., polymers polymerized from at least two comonomers) (e.g., poly (lactide-co-glycolide) copolymers), for example, wherein the weight ratio of polymer to bioactive material can be 1: 1 or less, e.g., 0.3: 1 to 1: 1; and (3) at least one lipophilic solvent or a mixture of hydrophilic and lipophilic solvents, wherein the volume ratio of hydrophilic to lipophilic solvents is from about 80: 20 to about 0: 100, such as from about 80: 20 to about 10: 90 or 5: 95, the hydrophilic and lipophilic solvents are from about 65: 35 to about 35: 65, and/or wherein the water-immiscible or lipophilic solvent is present in an amount of at least about 16.5 wt.% (e.g., including about 16.465 wt.%), such as from at least about 16.5 wt.% to about 45 wt.%, such as from at least about 16.5 wt.% to about 30 wt.% (e.g., at least about 29 wt.%) or at least greater than 40 wt.% (e.g., and at least about 42 to 45 wt.%); for example, less than 10% polymer and 1-10% bioactive material or about less than 7% (e.g., 6.7%) or 5% or less polymer may be present in such compositions, with the bioactive material content being less than or equal to about 10% or 5%.

The present invention still further relates to a liquid polymer composition consisting essentially of the above-described substances, wherein the liquid polymer composition is capable of forming a film-sealing liquid, for example, in situ, and/or has a long-lasting release, wherein the term "consisting essentially of …" is used in the patent literature to denote that it is included, and that the term does not include ingredients that may prevent the composition from forming a film-sealing liquid in this way.

The invention is further directed to methods of making and using such compositions. For example, a method for preparing such a composition comprising mixing the above components; for example, it is preferred to dissolve the polymer and the biologically active substance (as opposed to being suspended, encapsulated, or present as a solid, although the invention is not necessarily precluded, it is less preferred to dissolve the biologically active substance). Alternatively, a method of using such a composition comprises administering the composition of the invention to a patient or subject (an animal, e.g., a mammal such as a domestic animal, e.g., a companion or farm animal, or a human).

These and other areas of the invention will become apparent hereinafter. Various documents are cited below without admission that these are prior art with respect to the present invention. The references used herein and the references cited therein are hereby incorporated by reference.

Background

Biodegradable polymers have long been used in parenteral controlled release formulations of biologically active compounds. In one method the polymer is formed into microspheres that can be injected through a syringe and the bioactive compound is embedded in the microspheres. This method has proven to be somewhat impractical because the manufacturing process to produce a sterile and reproducible product is too difficult and the production cost is too high. In another method, both the biodegradable polymer and the bioactive material are dissolved in a biocompatible water-soluble solvent to provide a liquid composition. When the liquid composition is injected into the body, the solvent dissipates into the surrounding aqueous environment and the polymer forms a solid depot from which the bioactive material is released.

European patent application 0537559 relates to a polymer composition comprising a thermoplastic polymer, a rate modifier, a water-soluble bioactive material and a water-soluble organic solvent. Upon exposure to an aqueous environment (e.g., body fluids), the liquid composition forms a biodegradable microporous solid polymer matrix with controlled release of the water-soluble or water-dispersible bioactive material within about 4 weeks. The thermoplastic polymer may be polylactide, polyglycolide, polycaprolactone or copolymers thereof, among many lists, and may be used in high concentrations (45-50%). In many other lists the rate modifier may be triacetin (triacetin); but only ethyl heptanoate is exemplified; and the amount of rate modifier does not exceed 15%.

In fact, the following references are made with respect to patent documents:

U.S. Pat. No. 5	The inventors of the present invention
		4,150,1084,329,3324,331,6524,333,9194,389,330	Kleber et al, time, e.g., Ludwig, e.g., GrahamCouvreur, etc

4,489,0554,526,9384,530,8404,542,0254,563,4894,675,1894,677,1914,683,2884,758,4354,857,3354,931,2875,178,8725,252,7015,275,8205,478,5645,540,9125,447,7255,599,8525,607,6865,609,8865,631,0155,654,0105,700,4855,702,7175,711,9685,733,5664,938,7635,077,0495,278,2015,278,2025,288,4965,324,5195,324,5205,340,849

Couvreur et al, Churchill et al, Tice et al, UristKent et al, Tanaka et al, SchaafBohmBae et al, Ohtsubo et al, Jarrett et al, Changwanderer et al, Roordia et al, Scopellanos et al, Totakura et al, Bezwwada et al, Herbert et al, Johnson et al, Berde et al, LewisDunn et al, Dunn et al

5,368,8595,401,5075,419,9105,427,7965,487,8975,599,5525,632,7275,643,5955,660,8495,686,0925,702,7165,707,6475,717,0305,725,4915,733,9505,736,1525,744,1535,759,5635,780,044

Dunn et al, Lewis LewisP olson et al, Dunn et al, Tipton et al, Lewis et al, Dunn et al, Tipton et al, Dunn et al, Yewey et al, Dunn et al

These documents tend to provide compositions that form a solid, gel or agglomerate; for example, considerable amounts of polymer are contemplated in these documents, similar to European patent application 0537559.

Also mentioned are: shah et al (J.CONTROLLED RELEASE 1993, 27: 139-147) relate to sustained release formulations containing various concentrations of a biologically active compound of poly (lactide-co-glycolide) copolymer (PLGA) dissolved in a medium such as triacetin; lambert and Peck (J.ControlRelease 1995, 33: 189-) -195) investigated the release of proteins from a 20% PLGA solution dissolved in N-methylpyrrolidone upon exposure to aqueous fluids; and Shivley et al (J.ControlRelease 1995, 33: 237-.

Nevertheless, there is a need for compositions that can be released continuously over a long period of time, as well as for polymeric compositions that can form coating films or sealing liquids.

Objects and summary of the invention

We have surprisingly found that in contrast to previous compositions, formulations derived from polymer compositions containing substantial amounts of water-immiscible or lipophilic solvents and much less polymer than has been considered in the literature tend to be film-coating liquids rather than forming solids, gels or agglomerates (including "pore-containing" solids, gels or agglomerates in the literature). It can be seen that the prior art does not contemplate the use of lipophilic solvents or the amounts thereof and the amounts of oligomers used in the liquid polymer formulations of the present invention.

Accordingly, the objects of the invention may be any or all of the following: liquid polymer compositions comprising bioactive materials, such as compositions having long-term sustained release and/or formation of a coating or sealant fluid, and methods of making and/or using such compositions are provided.

The present invention provides a liquid polymer composition; such compositions, e.g. liquid polymer compositions, for example, for the controlled release of at least one biologically active substance, e.g. at least one hydrophobic biologically active substance, may for example form a film-sealing liquid in situ and/or may achieve a long-term sustained release, e.g. a high potency plasma profile (an efficiency above about 70%, such as at least about 80%, preferably at least about 90%, e.g. about 100% over a period of more than about 12 months) and/or plasma levels for at least about 50 or about 60 days or at least about 2 months or at least about 8 weeks, e.g. at least about 90 days or about 3 months or about 12 weeks or at least about 120 days or about 4 months or about 16 weeks, or at least about 150 days or about 5 months or about 20 weeks, or longer, e.g. up to about 1 year or longer, or 1 to 12 months or longer, in a patient or subject, e.g. an animal or human.

The present invention further provides a liquid polymer composition comprising: (1) 1-30% w/v of at least one biologically active substance (e.g. a hydrophobic biologically active substance); (2) 1-20% w/v of at least one biocompatible "polymer" (including "copolymers", i.e. polymers polymerized from at least two comonomers) (e.g. poly (lactide-co-glycolide) copolymers), e.g. wherein the weight ratio of polymer to bioactive substance may be 1: 1 or less, e.g. 0.5: 1 to 1: 1; and (3) a mixture of at least one hydrophilic solvent and at least one lipophilic solvent, for example a mixture of at least one biologically or physiologically or pharmaceutically or veterinarily acceptable hydrophilic solvent and at least one biologically or physiologically or pharmaceutically or veterinarily acceptable lipophilic solvent, wherein the volume ratio of hydrophilic to lipophilic (or hydrophobic) solvents is from about 80: 20 to about 0: 100, for example from about 80: 20 to about 10: 90 or 5: 95, the hydrophilic to lipophilic solvents is from about 65: 35 to about 35: 65, and/or wherein the water-immiscible or lipophilic solvent is present in an amount of at least about 16.5 wt.% (e.g. including about 16.465 wt.%), for example from at least about 16.5 to about 45 wt.%, for example from at least about 16.5 to about 30 wt.% (e.g. at least about 29 wt.%) or at least about 20 wt.% or from about 25 wt.% to about 30 wt.%, 35 wt.% (or both) of the water-immiscible or lipophilic solvent, 40 wt% or 45 wt%, or at least greater than 40 wt% (e.g., and at least about 42-45 wt%); for example, less than 10% polymer and 1-10% bioactive material or about less than 7% (e.g., 6.7%) or 5% or less polymer may be present in such compositions, with the bioactive material content being less than or equal to about 10% or 5%.

The present invention also further provides a liquid polymer composition consisting essentially of the above-described materials, wherein the liquid polymer composition is capable of forming a film-sealing liquid in situ and/or has a long-lasting release, for example, wherein the term "consisting essentially of …" is used in the patent literature to denote that it is ascribed to it, and that the term does not include ingredients that might prevent the composition from forming a film-sealing liquid in this way. Thus, for example, in certain embodiments, agents that tend to cause the composition to have one or more opposing properties, e.g., in situ, such as agents that tend to cause the composition to cure, such as curing agents, or agents that cause the composition to form pores, may not be required.

The invention further provides methods of making and using such compositions. For example, a method for preparing such a composition comprising mixing the above components; for example, it is preferred to dissolve the polymer and the biologically active substance (as opposed to being suspended, encapsulated, or present as a solid, although the invention is not necessarily precluded, it is less preferred to dissolve the biologically active substance). Alternatively, a method of using such a composition comprises administering the composition of the invention to a patient or subject (an animal, e.g., a mammal such as a domestic animal, e.g., a companion or farm animal, or a human).

The invention further provides a method consisting essentially of at least one step of preparing or using such a composition; wherein the liquid polymer composition is capable of forming a film-sealing liquid in situ and/or has a long-lasting release, for example, wherein the term "consisting essentially of …" is used in the patent literature to denote that it is assigned to, and does not include ingredients that might prevent the composition from forming a film-sealing liquid in this way. Thus, for example, in certain embodiments, steps that tend to cause the composition to have one or more opposing properties, e.g., in situ, may not be required, such as the addition of an agent that tends to cause the composition to cure, e.g., a curing agent, or an agent that causes the composition to form pores.

The biologically active substance may be any biological agent capable of providing a biological, physiological or therapeutic effect to an animal or human. The biologically active agent can be any one or more of the biologically active agents recognized by any of the documents cited herein or known in the art. The agent may also stimulate or inhibit a desired biological or physiological activity in an animal or human, including, without limitation, stimulating an immunogenic or immunological response.

Thus, the present invention provides an in situ formed film coated or encapsulated liquid implant capable of functioning as a delivery system for delivering drugs, agents and other bioactive agents to tissues adjacent to or remote from the site of implantation. The bioactive agent is preferably introduced into the film coating or encapsulating liquid and subsequently released into the surrounding tissue fluid and associated body tissue or organ. The composition may be applied to the implant site by any method suitable for administering fluids, such as by means of a syringe, needle, cannula, catheter, pressurized applicator, or the like.

Exemplary bioactive agents or substances include, without limitation, fipronil, avermectin, ivermectin, epimectin, milbemycin, phenylpyrazole, nodulisporic acid, estradiol benzoate, tremeblone acetate, norethindrone, progesterone, antibiotics such as macrolide or azalide antibiotics, or nonsteroidal anti-inflammatory drugs (NSAIDs), or combinations thereof.

It may therefore be an object of the present invention to provide for the release of at least one active ingredient, whether that ingredient is water-insoluble or water-immiscible; however, the invention is particularly applicable to hydrophobic biologically active substances.

The biocompatible polymer can be any biocompatible polymer, such as those recognized in the references cited herein. For example, the biocompatible polymer may have one or more or all of the following characteristics: can be bioerodible by cellular action, biodegraded by fluid components in a non-living organism, softened upon exposure to heat but returned to an original state upon cooling and capable of being substantially dissolved or dispersed in a water-soluble carrier or solvent to form a solution or dispersion. The polymer can aid in the formation of a coating film or a film-sealing liquid upon contact with an aqueous fluid. The class of polymers suitable for the present composition generally includes any having the above characteristics. Examples are polylactide, polyglycolide, polycaprolactone, polyanhydride, polyamide, polyurethane, polyesteramide, polyorthoester, polydioxanone, polyacetal, polyketal, polycarbonate, polyorthocarbonate, polyphosphazene, polyhydroxybutyrate, polyhydroxyvalerate, polyalkylene oxalate, polyalkylene succinate, polymalic acid, polyamino acid, polymethylvinyl ether, polymaleic anhydride, chitin, chitosan, and copolymers, terpolymers, or combinations or mixtures thereof. Polylactide, polycaprolactone, polyglycolide, and copolymers thereof are preferred polymers, with poly (lactide-co-glycolide) copolymers ("PLGA") being highly preferred. The PLGA may be constructed similarly to its use in the examples below or in the references cited herein.

The solvent may be any biologically or physiologically or pharmaceutically or veterinarily compatible hydrophobic and water soluble solvent, such as those recognized in the literature cited herein.

The hydrophilic solvent may be selected from propylene glycol, PEG, polyglycols such as polyethylene glycol 200, polyethylene glycol 300 and polyethylene glycol 400, diethylene glycol ethyl ether (Transcutol), isopropylidene glycerol (Solketal), dimethyl isosorbide (Arlasolve DMI), propylene carbonate, glycerol, glycofurol, pyrrolidones such as N-methyl pyrrolidone and 2-pyrrolidone, isopropylidene glycerol, dipropylene glycol methyl ether, and mixtures thereof. Other solvents may also be used as hydrophilic solvents. For example, the hydrophilic solvent may be C₂-C₆Alkanols (e.g. ethanol, propanol, butanol), acetone, alkyl esters such as methyl acetate, ethyl lactate, alkyl ketones such as methyl ethyl ketone, dialkyl amides such as dimethylformamide, dimethyl sulfoxide, dimethyl sulfone, tetrahydrofuran, cycloalkyl amides such as caprolactam, decylmethyl sulfoxide, oleic acid, propylene carbonate, aromatic amides such as N, N-diethyltoluamide and 1-dodecylazacycloheptan-2-one. The hydrophilic solvent may be a mixture of these solvents.

The lipophilic or non-water miscible or hydrophobic solvent may be selected from triethyl citrate, Miglyol812, Miglyol 840, Crodamol GTCC, triacetin or benzyl benzoate; and can useFurther lipophilic solvents, e.g. hydrophobic rate regulators or plasticizers such as fatty acids, triglycerides, oils such as castor oil, soya oil or other vegetable oils or derivatives thereof such as epoxidized or hydrogenated vegetable oils such as epoxidized soya oil or hydrogenated castor oil, sterols, higher alkanols (e.g. C)₆Or higher), glycerol, and the like. The lipophilic solvent may be a mixture of these solvents.

Other solvents may include: glycol ethers such as propylene glycol monomethyl ether, dipropylene glycol monomethyl ether and diethylene glycol ethyl ether, diethylene glycol ethyl ether acetate, dipropylene glycol methyl ether (Dowanol DPM), dipropylene glycol methyl ether acetate, glycerol formal, glycerol furfural, isopropyl myristate, N-dimethylacetamide, PEG 300, propylene glycol and polar aprotic solvents such as DMSO.

In certain embodiments less than 10% polymer and 1-10% active compound may be present; for example, the ratio of PLGA polymer to active compound is less than or equal to 1: 1. (see, for example, the examples wherein, for example, 0.2575/25 PLGA was dissolved in glycerol formal to give a 2.5ml solution; 75/25PLGA was dissolved in triacetin in another flask to give a 2.5ml solution; both solutions were mixed and added to one flask containing 0.50g of the active ingredient dissolved in the mixed PLGA solution; the amount of triacetin present in the formulation was about 42% by weight; the other formulations contained as little as 6.7% and 5% PLGA content, drug content was 10% or 5%).

When implanted, i.e. injected, the liquid formulation of the invention forms what appears to be "a semi-solid supply station with a thin film of polymer" from gross examination of the subject or patient into which the formulation is implanted. While not wishing to be bound by any one particular theory, the replenishment station need not be solid or semi-solid (as that term is commonly understood); but a film coating or sealing liquid (the polymer aids in film formation). Over time, the supply station loses its carrier (solvent) and degradation of the polymer occurs.

Although there is diffusion through the membrane (in the preferred embodiment the color is generally white), it is believed that there are no holes in the replenishment station; and it is likely that the liquid polymer formulation does not form a solid or agglomerated mass or gel mass in situ. These beliefs are based on the fact that: the amount of polymer in the formulations of the present invention is significantly less than that used in the prior art; the amount of water insoluble or lipophilic solvent present in the formulations of the present invention is significantly greater than the amount of any "rate modifying agent" or similar solvent used in the prior art (such that the replenishment station center remains in a liquid state); and the polymer biodegrades as the active ingredient diffuses through the membrane (a very thin membrane, which in the preferred embodiment is generally white). The formulations of the present invention are well suited for the delivery of lipophilic (hydrophobic) active ingredients.

These and other aspects are disclosed in or are apparent from, and encompassed by, the following detailed description.

Brief Description of Drawings

The following detailed description, given by way of example, is not intended to limit the invention to the particular embodiments described, but is to be used in an understanding of the invention with reference to the accompanying drawings, in which:

figure 1 depicts plasma levels of 6-amino-3-cyano-1- (2, 6-dichloro-4-thiopentafluorophenyl) -4- (trifluoromethylthio) pyrazole in dogs treated with the formulation of example 1;

FIG. 2 depicts plasma levels of ivermectin in cattle treated with 3 of the ivermectin formulations of example 2;

figure 3 depicts plasma levels of eporinomectin in pigs treated with the eporinomectin formulation of example 3.

Detailed description of the invention

The present invention provides liquid polymer compositions for the delivery of biologically active substances.

The present invention provides a liquid polymer composition; such compositions, e.g. liquid polymer compositions, for example, for the controlled release of at least one biologically active substance, e.g. at least one hydrophobic biologically active substance, may for example form a film-sealing liquid in situ and/or may achieve a long-term sustained release, e.g. a high potency plasma profile (an efficiency above about 70%, such as at least about 80%, preferably at least about 90%, e.g. about 100% over a period of more than about 12 months) and/or plasma levels for at least about 50 or about 60 days or at least about 2 months or at least about 8 weeks, e.g. at least about 90 days or about 3 months or about 12 weeks or at least about 120 days or about 4 months or about 16 weeks, or at least about 150 days or about 5 months or about 20 weeks, or longer, e.g. up to about 1 year or longer, or 1 to 12 months or longer, in a patient or subject, e.g. an animal or human.

The present invention further provides a liquid polymer composition comprising: (1) about 1-30% w/v of at least one biologically active substance (e.g., a hydrophobic biologically active substance); (2) about 1-20% w/v of at least one biocompatible "polymer" (including "copolymers", i.e., polymers polymerized from at least two comonomers) (e.g., poly (lactide-co-glycolide) copolymers), e.g., wherein the weight ratio of polymer to bioactive agent can be 1: 1 or less, e.g., 0.5: 1 to 1: 1; and (3) at least one lipophilic solvent or a mixture of at least one hydrophilic solvent and at least one lipophilic solvent, for example a mixture of at least one biologically or physiologically or pharmaceutically or veterinarily acceptable hydrophilic solvent and at least one biologically or physiologically or pharmaceutically or veterinarily acceptable lipophilic solvent, wherein the volume ratio of hydrophilic to lipophilic (or hydrophobic) solvents is from about 80: 20 to about 0: 100, for example from about 80: 20 to about 10: 90 or from about 80: 20 to about 5: 95, the hydrophilic to lipophilic solvents is from about 65: 35 to about 35: 65, and/or wherein the water-insoluble or lipophilic solvent is present in an amount of at least about 16.5 wt.% (e.g. including about 16.465 wt.%), for example from at least about 16.5 to about 45 wt.%, for example from at least about 16.5 to about 30 wt.% (e.g. at least about 29 wt.%), or from at least about 20 wt.% or from about 25 to about 30 wt.% (e.g. to about 25 wt.%), 35 wt%, 40 wt%, or 45 wt%, or at least greater than 40 wt% (e.g., and at least about 42-45 wt%); for example, less than 10% polymer and 1-10% bioactive material may be present in such compositions, or, alternatively, about less than 7% (e.g., 6.7%) or 5% or less polymer, with the bioactive material content being less than or equal to about 10% or 5%.

The present invention also further provides a liquid polymer composition consisting essentially of the above-described materials, wherein the liquid polymer composition is capable of forming a film-sealing liquid in situ and/or has a long-lasting release, for example, wherein the term "consisting essentially of …" is used in the patent literature to denote that it is ascribed to it, and that the term does not include ingredients that might prevent the composition from forming a film-sealing liquid in this way. Thus, for example, in certain embodiments, agents that tend to, for example, cause the composition to have one or more opposing properties in situ, e.g., agents that tend to cause the composition to cure, such as curing agents, or agents that cause the composition to form pores, may not be required.

The present invention still further provides methods of making and using such compositions, as discussed herein.

The polymers and solvents used in the present invention may be those discussed herein.

The biologically active substance may be any biological agent capable of providing a biological, physiological or therapeutic effect to an animal or human. The biologically active agent can be any one or more of the biologically active agents recognized by any of the documents cited herein or known in the art. The agent may also stimulate or inhibit a desired biological or physiological activity in an animal or human, including, without limitation, stimulating an immunogenic or immunological response.

The in situ formed implants may also provide a delivery system for delivering the bioactive agent to adjacent or remote in vivo tissues and organs. Biologically active agents that may be used alone or in combination in the present compositions and implants include drugs, medicaments, or any suitable biologically, physiologically, or pharmacologically active substance that provides local or systemic biological or physiological activity in an animal, including a human, and that is capable of being released from a depot into an adjacent or surrounding aqueous fluid.

The biologically active agent may be miscible in the polymer and/or solvent to provide a homogeneous mixture with the polymer, or insoluble in the polymer and/or solvent to form a suspension or dispersion with the polymer. It is highly preferred that the biologically active agent is mixed with the other components of the composition of the invention immediately after application of the composition of the invention to the site of implantation. It is also preferred that the biologically active agent is not miscible with water, e.g., at most only sparingly soluble in water or has low solubility in water or can be dissolved in lipophilic (hydrophobic) solvents. It is also preferred that the biologically active agent does not contain functional groups that would interfere with the polymer. These conditions are readily determined by one skilled in the art simply by comparing the structure of the biologically active agent and the polymer reaction site.

The compositions and in situ-forming implants contain the biologically active agent in an amount effective to provide the desired biological, physiological, pharmacological and/or therapeutic effect, optionally according to the desired release profile, and/or duration of release. It is also preferred that the bioactive agent is included in the polymer composition in an amount effective to provide an acceptable solution or dispersion viscosity.

Suitable bioactive agents include substances used to prevent infection at the site of implantation, such as antiviral, antibacterial, antiparasitic, antifungal substances and combinations thereof. The agent may also be a substance that can be used as a stimulant, sedative, hypnotic, analgesic, antispasmodic, and the like. The delivery system may comprise a plurality of biologically active agents, either alone or in combination. Examples of such biologically active agents include, but are not limited to: anti-inflammatory agents such as hydrocortisone, prednisone, fludrocortisone, triamcinolone, dexamethasone, betamethasone, etc. Antibacterial agents such as penicillin, cephalosporin, vancomycin, bacitracin, multi-chain myceliophin, tetracycline, chloramphenicol, erythromycin, streptomycin, etc. Antiparasitic agents such as atebrine, chloroquine, quinine, and the like. Antifungal agents such as nystatin, gentamicin, dichlorbenzimidazole, tolnaftate, undecanoic acid and its salts, etc. Antiviral agents such as vidarabine, acyclovir, ribavirin, amantadine hydrochloride, idoxuridine, dideoxyuridine, interferon, etc. Antineoplastic agents such as methotrexate, 5-fluorouracil, bleomycin, tumor necrosis factor, toxin-binding tumor specific antibodies, and the like. Analgesic agents such as salicylic acid, salicylate, acetaminophen, ibuprofen, morphine, phenylbutazone, indomethacin, sulindac, toluoylpyretic acid, and sodium benzoylate. Local anesthetics such as cocaine, benzocaine, procaine, lidocaine, and the like. Vaccines, or antigens, epitopes, immunogens of human or animal pathogens such as hepatitis, influenza, measles, mumps, rubella, haemophilus, diphtheria, tetanus, rabies, poliomyelitis, and veterinary vaccines. Central nervous system agents such as tranquilizer, sedative, antidepressant, hypnotic, B-adrenergic blocker, dopamine, etc. Growth factors such as colony stimulating factor, epidermal growth factor, erythropoietin, fibroblast growth factor, nerve growth factor, human growth hormone, platelet derived growth factor, insulin-like growth factor, etc. Hormones such as progesterone, estrogen, testosterone, follicle stimulating hormone, chorionic gonadotropin, insulin, endorphin, growth hormone, etc. Antihistamines such as diphenhydramine, clotrimide, clorazine, promethazine, cimetidine, terfenadine, and the like. Cardiovascular agents such as verapamil hydrochloride, digitalis, streptokinase, paparefine nitrate, diisopropyramide phosphate, isosorbide dinitrate, and the like. Antiulcer agents such as cimetidine hydrochloride, sopropamide iodide, propantheline bromide, etc. Bronchodilators such as metaprotal sulfate, aminophylline, albuterol, etc. Vasodilators such as theophylline, nicotinic acid, nicotinate, amyl nitrate, minoxidil, chlorothiazide, nifedipine, and the like.

Biologically active agents for use in the formulations of the present invention are well known to practitioners of the invention concerned. Classes of biologically active agents contemplated in the formulations of the present invention include insecticides, acaricides, parasiticides, growth hormones, and oil-soluble non-steroidal anti-inflammatory drugs (NSAIDs). Specific compounds belonging to these classes include, for example, avermectins, milbemycins, nodulisporic acid and its derivatives, estrogens, progestins, androgens, substituted pyridylmethyl derivatives, phenylpyrazoles, and COX-2 inhibitors.

The avermectins and milbemycins series of compounds are effective anthelmintics and antiparasitic agents against a wide range of parasites in and out of the body. The compounds belonging to this series are either natural products or semisynthetic derivatives thereof. The structures of these two series of compounds are closely related and they both participate in the complex 16-membered macrolide ring; however, milbemycins do not contain an aglycone substituent at the 13-position of the lactone ring. The natural product avermectins are disclosed in U.S. patent 4,310,519 to Albers-Schonberg et al, while the 22, 23-dihydroavermectin compounds are disclosed in U.S. patent 4,199,569 to Chabala et al. For a general discussion of avermectins, including a discussion of their use in humans and animals, see "ivermectin and Abamectin" edited by W.C. Campbell, Springer-Verlag, New York (1989). Furthermore, biologically active agents such as avermectins or ivermectin may be used in combination with other biologically active agents; and with regard to the problems associated with the combination of avermectins, ivermectin and biologically active agents, reference is made in particular to U.S. patent 4,468,390 to Kitano, U.S. patent 5,824,653 to Beuvry et al, U.S. patent 4,283,400 to von Bittera et al, European patent application 0007812A 1 published on 6.2.1980, UK patent specification 1390336 published on 4.9.1975, European patent application 0002916A 2, Ancare New Zealand patent 237086, Bayer New Zealand patent 176193 published on 11.19.1975, etc.

Naturally occurring milbemycins are described in U.S. patent 3,950,360 to Aoki et al, and in a number of references cited in the Merck index 12 edition, eds. s.budavari, Merck & co., inc. Semi-synthetic derivatives of these classes of compounds are well known in the art and are described, for example, in

Us 5,077,308, us 4,859,657, us 4,963,582, us 4,855,317, us 4,871,719, us 4,874,749, us 4,427,663, us 4,310,519, us 4,199,569, us 5,055,596, us 4,973,711, us 4,978,677, and us 4,920,148.

nodulisporic acid and its derivatives are a class of acaricides, antiparasitic agents, insecticides and insect repellents known to practitioners in the art. These compounds are useful for treating or preventing infections in humans and animals. These compounds are described, for example, in U.S. Pat. No. 5,399,582 and WO 96/29073. Thus, the compounds can be applied in combination with other insecticides, parasiticides and acaricides. Such co-administration includes anthelmintics, as discussed above, including ivermectin, avermectin, and emamectin, as well as other agents such as thiabendazole, febante (anthelmintic), or methylthiopyrimidine; phenyl pyrazoles such as fipronil; and insect growth regulators such as lufenuron. Such combined administration is also contemplated by the present invention.

Generally all types of such pesticides can be used in the present invention. An example of this type includes substituted pyridylmethyl derivatives such as imidacloprid. Such agents are described, for example, in us patent 4,742,060 or EP 892,060.

Pyrazoles such as phenylpyrazole and N-arylpyrazoles are another class of insecticides having excellent insecticidal activity against parasites on animals of all insect pests including blood-sucking pests such as ticks, fleas and the like. Such agents kill pests by acting on gamma-butyric acid receptors of invertebrates. Such agents are described, for example, in U.S. Pat. No. 5,567,429, U.S. Pat. No. 5,122,530, EP 295,117, and EP 846686A 1 (or Bank GB 9625045 filed 11/30 1996, which is also considered equivalent to USSN 309,229 filed 11/17 1997). It is within the skill of the practitioner to decide which compound to use in the formulations of the invention.

Insect growth regulators are another class of insecticides or acaricides that may also be provided in the formulations of the present invention. Compounds belonging to this class are well known to practitioners and represent a wide range of different chemical classes. These compounds all act by interfering with the development or growth of the pest. Insect growth regulators are described, for example, in U.S. patent 3,748,356; us patent 3,818,047; us patent 4,225,598; us patent 4,798,837; and U.S. patent 4,751,225, and EP 179,022 or u.k.2,140,010. It is also within the skill of the practitioner to decide which compound to use in the formulations of the invention.

Estrogens, progestins, and androgens refer to a class of chemical compounds that are also well known to practitioners in the art. Indeed, estrogens and progestins are the most widely used prescription drugs and can be used, for example, alone or in combination for contraception or hormone replacement therapy in postmenopausal women. Estrogens and progestins are either naturally occurring or synthetically prepared. Such compounds also include estrogen or progesterone receptor antagonists. Antiestrogens such as tamoxifen and clomiphene are used to treat breast cancer and infertility. Antiprogestins are used as contraceptives and anticancer agents, as well as in induced abortion or to terminate pregnancy.

Androgens and antiandrogens are structurally related to estrogens and progestins because they are also biosynthesized from cholesterol. These compounds are based on testosterone. Androgens are used to treat hypogonadism and to promote muscle development. Antiandrogens are used, for example, to treat prostatic hyperplasia and cancer, acne and male pattern baldness, and to suppress sexual arousal in sexually criminal men. Estrogens, progestins and androgens are described, for example, in "the pharmacological basis for treatment by Goodman and Gilman" 9 th edition, edited by J.G.Handman and L.Elimbrid, chapters 57-60, pp 1411-1485, McGraw Hill, New York (1996) or "principles of pharmaceutical chemistry" 2 nd edition, edited by W.O.Foye, chapter 21, pp 495-559, Lea & Febiger, Philadelphia (1981).

Estrogens, progestins, and androgens are also used in animal management as growth promoters for feeding animals. Such compounds are known in the art as growth-promoting steroids for animals such as cattle, sheep, pigs, poultry, rabbits and the like. Delivery systems to promote animal growth are described in, for example, U.S. patent 5,401,507, U.S. patent 5,288,469, U.S. patent 4,758,435, U.S. patent 4,686,092, U.S. patent 5,072,716, and U.S. patent 5,419,910.

NSAIDs are well known in the art. Classes of compounds falling within this class include salicylic acid derivatives, p-aminophenol derivatives, indole and indene acetic acids, heteroaryl acetic acids, aryl propionic acids, anthranilic acids (fenamates), enolic acids and alkanones. NSAIDs exert their activity by interfering with the biosynthesis of prostaglandins through irreversible or reversible inhibition of cyclooxygenase. Also included are COX-2 inhibitors, which act by inhibiting the COX-2 receptor. The compounds have analgesic, antipyretic and non-steroidal anti-inflammatory properties. Compounds belonging to this class are described, for example, in chapter 27 of "Goodman and Gilman" at page 617-658 or chapter 22 of Foye at page 561-590 and in U.S. Pat. No. 3,896,145, U.S. Pat. No. 3,337,570, U.S. Pat. No. 3,904,682, U.S. Pat. No. 4,009,197, U.S. Pat. No. 4,223,299 and U.S. Pat. No. 2,562,830, and in the special agents listed in the "Merck index".

Macrolides are a class of antibiotics that contain a polylactone ring to which one or more deoxy sugars are attached. Macrolides are generally bacteriostatic, but have been shown to be bactericidal at high concentrations against very sensitive organisms. Macrolides are most effective against gram-positive cocci and bacilli, although they do also have some activity against certain gram-negative organisms. Macrolides exert their bacteriostatic activity by reversibly linking 50S ribosomal subunits to inhibit bacterial protein synthesis. ("pharmacological basis for treatment of Goodman & Gillman" 9 th edition, edited by J.G.Hadman and L.E.Limbrid, Chapter 47, pp 1135-1140, McGraw Hill, New York (1996)).

Macrolides are colorless and are usually crystalline. The compounds are generally stable in near neutral solutions, but have limited stability in acidic or basic solutions. This is because the glycosidic bond is hydrolyzed in acid and the lactone ring is saponified in base ("principle of pharmaceutical chemistry" 2 nd edition, W.F. Foye eds., Chapter 31, page 782-785, Lea & Febiger, Philadelphia (1981)). Thus, there is a need for pharmaceutical or veterinary compositions for parenteral injection, e.g. intravenous, intramuscular, subcutaneous administration of macrolide antibiotics.

The biologically active agent of the present invention may be a macrolide, as macrolides are soluble in many organic solvents and only sparingly soluble in water. Solutions of macrolides in organic solvent systems are administered by intramuscular and subcutaneous routes to humans and veterinary practice.

Macrolides include erythromycin and its derivatives as well as other derivatives such as azalides. Erythromycin (MW 733.94 Dalton) is the common name for macrolide antibiotics produced by the growth of a species of streptomyces erythroseous. It is a mixture of three erythromycins A, B and C, mainly consisting of erythromycins A. Its chemical name is (3R)^*，4S^*，5S^*，6R^*，7R^*，9R^*，11R^*，12R^*，13S^*，14R^*) -4- [ (2, 6-dideoxy-3-C-methyl-3-O-methyl-alpha-L-ribose-hexopyranosyl) -oxy]-14-ethyl-7, 12, 13-trihydroxy-3, 5, 7, 9, 11, 13-hexamethyl-6 [ [3, 4, 6-trisdeoxy-3- (dimethylamino) - β -D-xylose-hexopyranosyl]Oxy radical]Oxetacyclotetradecane-2, 10-dione, (C)₃₇H₆₇NO₁₃)。

Erythromycin has a broad and substantial bacteriostatic effect on many gram-positive and some gram-negative bacteria, as well as other organisms including mycoplasma, spirochetes, chlamydia and rickettsia. In humans, it is found to be useful in treating many infections. It finds widespread use in veterinary practice for the treatment of infectious diseases such as pneumonia, mastitis, metritis, rhinitis and bronchitis in cattle, pigs and sheep.

Other derivatives of erythromycin include carbenicillin, clarithromycin, josamycin, doxycycline, medecamycin, mikanomycin, mithramycin, oleandomycin, pristinamycin, rokitamycin, rosamycin, roxithromycin, spiramycin, tylosin, triacetyl oleandomycin, and veganmycin. Like erythromycin, many of these derivatives are also present as component mixtures. For example, a carbamycin is a mixture of carbamycin A and carbamycin B. The column crystal leucomycin is a component A in various proportions₁，A₂，A₃，A₉，B₁-B₄And a mixture of U and V is present. Component A₃Also known as josamycin and pillared baimycin V is also known as validamycin. Midecamycin as the main component and midecamycin A as the secondary component₂，A₃And A₄. Similarly, the mikamycin is a mixture of several components, mikamycin A and B. Mandarin A is also known as victimycin M₁. The pristinamycin is prepared from pristinamycin I_A，I_BAnd I_C(separately with Vitamycin B)₂，B₁₃And B₂Same) and pristinamycin II_AAnd II_B(and Vitamycin M)₁And 26, 27-dihydrovictamycin M₁Same) composition. Spiramycin consists of three components, spiramycin I, II and III. The vitamin A and the vitamin B are respectively composed of vitamin A and vitamin E S₁And vemuramycin M₁And (4) forming. All of these components can be used in the present invention. The sources of these macrolides are well known to practitioners and are described in references such as the Merck index 12 edition, s&Co., inc. whitehouse association, new jersey (1996).

azalides are semi-synthetic macrolide antibiotics related to erythromycin A and show similar dissolution properties. The structure of azithromycins is known. Useful azalide compounds are disclosed in EP 508699, which is incorporated herein by reference. Corresponding base and acid addition salts and ester derivatives of macrolide compounds are also contemplated for use in the present invention. These salts are formed from the corresponding organic or inorganic acids or bases. These derivatives include the conventional hydrochloride and phosphate salts and the acetate, propionate and butyrate esters. These derivatives may have different names. For example, the phosphate salt of oleandomycin is oleandomycin and the triacetyl derivative of oleandomycin is triacetyl oleandomycin. Rokitamycin is pristinamycin V4-B-butyrate and 3B-propionate.

Other antibiotics may also be used as biologically active agents in the practice of the present invention.

The biologically active agent may be, for example, a peptide or a protein. The biologically active agent may also be a substance or metabolic precursor thereof that promotes the growth and survival of cells and tissues or increases the activity of functional units such as blood cells, neurons, muscle, bone marrow, bone cells and tissues, and the like. For example, the bioactive agent can be a nerve growth promoting substance, such as gangliosides, phosphatidylserines, nerve growth factors, brain derived neurotrophic factors, fibroblast growth factors, and the like. To promote tissue growth, the bioactive agent may be a hard or soft tissue promoting substance or a combination thereof. Suitable tissue growth promoters include, for example, Fibronectin (FN), Endothelial Cell Growth Factor (ECGF), Cementum Attachment Extract (CAE), Human Growth Hormone (HGH), periodontal ligament cell growth factor (PDGF), Fibroblast Growth Factor (FGF), animal growth hormone, Platelet Derived Growth Factor (PDGF), Epidermal Growth Factor (EGF), the protein growth factor Interleukin-1 (IL-1), transforming growth factor (TGF. beta. -2), insulin-like growth factor II (ILGF-II), human alpha-thrombin (HAT), bone inducing factor (OIF), Bone Morphogenetic Protein (BMP) or proteins derived therefrom, demineralized bone matrix, and release factors thereof. Furthermore, the agent may be a bone growth promoting substance such as hydroxyapatite, tricalcium phosphate, di-or polyphosphonic acid, an antiestrogen, a sodium fluoride preparation, a substance with a phosphate to calcium ratio similar to natural bone, or the like. The bone growth promoting substance may be in the form of, for example, bone chips, bone crystals, or inorganic components of bone and/or teeth, synthetic hydroxyapatite, or other suitable forms. The agent can further treat bone metabolism disorders such as abnormal calcium and phosphate metabolism by, for example, inhibiting bone resorption, promoting bone mineralization, or inhibiting calcification. See, for example, U.S. patent 4,939,131 to Benedict et al, U.S. patent 4,942,157 to Gall et al, U.S. patent 4,894,373 to Young, U.S. patent 4,904,478 to Walsdorf et al, and U.S. patent 4,911,931 to Baylink et al, U.S. patent 4,916,241 to Hayward et al, U.S. patent 4,921,697 to Peterlik et al, U.S. patent 4,902,296 to Bolander et al, U.S. patent 4,294,753 to uri, U.S. patent 4,455,256 to uri, U.S. patent 4,526,909 to uri, U.S. patent 4,563,489 to uri, U.S. patent 4,596,574 to uri, U.S. patent 4,619,989 to uri, U.S. patent 4,761,471 to uri, U.S. patent 4,789,732 to uri, U.S. patent 4,795,804 to uri, and U.S. patent 4,857,456 to uri, the disclosures of which are incorporated herein by reference.

Again, the bioactive agent or bioactive agent can be an anti-tumor agent, or an anti-cancer agent.

The biologically active agent may be included in the composition, for example, in the form of an uncharged molecule, molecular complex, salt, ether, ester, amide, or other form to provide effective biological or physiological activity.

For bioactive agents useful in the practice of the present invention, reference is also made to Williams and Chern, US and PCT application "Long acting injectable formulations containing hydrogenated castor oil", filed 9/14.1998, US Ser. No. 09/15277, PCT application No. US98/190, claiming priority from US application No. 60/067,374, which is hereby incorporated by reference.

From the foregoing, the bioactive agent can be altered. The amount suitable for use in the formulations of the present invention may be determined by the skilled artisan based on the knowledge in the art without undue experimentation, and the present disclosure contemplates factors commonly considered by one of skill in the medical, veterinary or pharmaceutical arts, such as the species, age, weight, general health, sex of the subject or patient or animal or human, and the condition of treatment and LD involved₅₀(median lethal amount) and other properties of the biologically active substance.

Thus, administration of the compositions of the present invention will ultimately be accomplished in accordance with the knowledge and protocols of a professional, e.g., a physician or veterinarian, or, if specific, a dentist, involved in the health care of the patient or subject or animal or human. The selection of a particular composition will depend on the severity of the condition or treatment, and the choice will be determined by the professional involved in the health care. Injection administration or other methods of applying a liquid to or into tissue may be used. The amount and concentration of the composition administered to a patient, subject, animal or human will generally be sufficient to accomplish the intended task. For administration of the biologically active agent, the amount and release rate will follow the recommendations of the manufacturer of the biologically active agent. In general, the concentration of the biologically active agent in the liquid polymer formulation can be from 0.01mg per gram of the mixture to 400mg per gram of the mixture.

In certain embodiments, the present invention provides a liquid polymer composition for the controlled release of a hydrophobic bioactive material, comprising:

(a) 1-30% w/v hydrophobic bioactive substance;

(b) 1-20% w/v poly (lactide-co-glycolide) copolymer;

(c) a mixture of hydrophilic and lipophilic solvents, wherein the volume ratio of hydrophilic to lipophilic solvents is from about 80: 20 to about 5: 95.

In a certain preferred embodiment, the biologically active substance, such as at least one hydrophobic biologically active substance, is present in a concentration of 1-10% w/v, more preferably 5-10% w/v.

In another preferred embodiment, the polymer, such as poly (lactide-co-glycolide) copolymer, is present in a concentration of 1-10% w/v, more preferably 1-5% w/v.

In another preferred embodiment, the weight ratio of polymer, such as poly (lactide-co-glycolide) copolymer, to biologically active substance, such as at least one hydrophobic biologically active substance, is 1: 1 or less; more preferably from 0.5: 1 to 1: 1.

In another preferred embodiment, the volume ratio of hydrophilic to lipophilic solvents is from about 65: 35 to about 35: 65.

In another aspect the present invention provides a liquid polymer composition for the controlled release of a hydrophobic bioactive substance, comprising:

(a) a hydrophobic bioactive substance;

(b) poly (lactide-co-glycolide);

(c) a mixture of glycerol formal and glycerol triacetate.

In another aspect, the invention provides a method for the controlled release of at least one biologically active substance, such as at least one hydrophobic biologically active substance, comprising injecting an animal with a liquid polymer composition as described herein.

In addition to the above, the following terms as used herein are defined as follows (unless otherwise indicated):

"Polymer" includes "copolymer"; "copolymer" is a polymer obtained by polymerizing at least two monomers; thus, "copolymer" may include "terpolymer" or a polymer derived from two, three or more monomers.

"hydrophobic biologically active substance" means a compound for human or animal health which has a solubility in water at room temperature of < 2%, preferably < 1%. Examples of hydrophobic bioactive materials suitable for use in the present invention include, but are not limited to, avermectins (e.g., ivermectin, eprinomectin, and the like), milbemycins, phenylpyrazoles, nodulisporic acid, and derivatives such as those disclosed in U.S. Pat. No. 5,399,582 and WO96/29073, estradiol benzoates, norandrostenol ketone acetates, progestins, norethindrone, water-insoluble NSAIDs, and the like.

"Poly (lactide-co-glycolide)" means a copolymer of lactic acid and glycolic acid, the ratio of lactide to glycolide being from 95: 5 to 50: 50, preferably from 75: 25 to 65: 35. The lactic acid may be d-or l-or dl-lactic acid. The copolymer may be a single copolymer or a mixture of copolymers within the parameters defined above.

"hydrophilic solvent" means a solvent which is miscible with water, preferably one which forms a single phase solution when mixed with water in a ratio of 1: 9 to 9: 1. Examples of hydrophilic solvents suitable for the present invention include, but are not limited to, glycerol-formal, glycerol furfural, N-methylpyrrolidone, 2-pyrrolidone, isopropylidene glycerol, dipropylene glycol methyl ether, and mixtures thereof.

By "lipophilic solvent" is meant a solvent that is immiscible with water, preferably having a solubility in water of less than 10% at room temperature. Examples of lipophilic solvents suitable for the present invention include, but are not limited to, triacetin, benzyl benzoate, and mixtures thereof.

Once injected, the liquid compositions of the present invention are capable of providing long-term drug release, rather than pulsatile drug release as typical of existing liquid injectable formulations. Without being bound by theory, it is assumed that upon injection, the liquid formulation of the present invention initially forms a supply station (appearing "semi-solid") with a layer of thin film made of polymer around the liquid core, while a portion of the hydrophilic solvent carries the bioactive compound dissolved with it away from the supply station. Drug release from the supply station initially occurs primarily through membrane permeation. At a given polymer and drug concentration, the membrane permeation and initial drug release rate are controlled by the ratio of hydrophilic and lipophilic solvents in the liquid carrier. Over time, the supply station loses its liquid carrier and polymer degradation gradually becomes the primary drug release mechanism. Thus, proper adjustment of the liquid formulation composition allows for overlap of osmotic and erosion control drug release and results in a gradual and extended drug release frame that can last over a long period of time. Thus, the depot biodegrades, without wishing to be bound by any particular theory, without necessarily forming a solid or other physical form associated with prior art compositions.

The presence of the lipophilic solvent in the liquid compositions of the present invention reduces the initial release of the biologically active compound, thus eliminating the typical pulsatile drug release of existing liquid injectable formulations in which most hydrophilic carriers are used. The presence of hydrophilic solvents facilitates the formation of a polymer film that prevents precipitation of the biologically active compound, thus allowing a higher level of drug release than would occur if only lipophilic carriers were used. In the present invention, the preferred ratio of hydrophilic to lipophilic solvent is from 80: 20 to 20: 80, most preferably from 65: 35 to 35: 65.

Other factors that may affect the performance of the liquid formulations of the present invention include: (1) polymer, e.g., PLGA polymer concentration, (2) ratio of bioactive compound to polymer, (3) ratio of comonomer, e.g., lactide to glycolide, in the polymer, and (4) molecular weight of the polymer. Factors (3) and (4) are well known in the art (see literature cited herein). However, the present invention is significantly different from the existing techniques particularly in (1) and (2).

The liquid formulations of the present invention contain no more than 20% polymer, e.g., PLGA polymer, preferably less than 10% polymer, to maintain a relatively constant drug release rate while ensuring a relatively long drug release duration (greater than 3 months). The concentration of polymer, e.g. PLGA, in the formulations of the present invention is therefore in sharp contrast to that in known formulations, which prescribes a substantial proportion of polymer, e.g. PLGA polymer. The concentration of the biologically active substance in the liquid formulation may be 1% to 30%. Preferably the ratio of polymer, e.g. PLGA polymer to bioactive compound is less than or equal to 1: 1; this ratio is significantly less than what is normally specified. Within the ranges described herein, higher polymer concentrations decrease the drug release rate and increase the polymer: the proportion of biologically active compound also reduces the release rate.

Liquid compositions may be prepared by dissolving all of the solid components in the carrier under conventional manufacturing conditions for sterile injectable products. The compositions of the present invention may contain additional inert materials commonly used in parenteral injection formulations, including but not limited to antimicrobials, antioxidants, and the like.

The liquid composition of the present invention can be administered to a warm-blooded animal such as human, bovine, ovine, porcine, canine, equine, feline, etc. (e.g., mammals such as human and companion animals and farm animals) by intramuscular or subcutaneous injection. The formulations are generally prepared to contain 1-30%, preferably 1-10% of the biologically active compound. For example, the formulation may contain 50-100mg or about 5-10% w/v avermectin compound per ml of solution in about 1ml of the preferred dosage volume for treating 50kg body weight cattle. However, depending on the activity of the compound and the animal being treated, as little as 1% of the biologically active compound may be useful.

The following examples are intended to illustrate the invention and should not be construed as limiting it in any way.

Example 1

Preparation of long-acting injectable preparation containing 6-amino-3-cyano-1- (2, 6-dichloro-4-thiopentafluorophenyl) -4- (trifluoromethylthio) pyrazole

Poly (DL-lactide/glycolide) 75/25(PLGA, 0.25g) was dissolved in sufficient glycerol-formal to give a 2.5ml solution. In a separate flask poly (DL-lactide/glycolide) 75/25(0.25g) was dissolved in sufficient triacetin to give 2.5ml of a solution. The two PLGA solutions were mixed thoroughly and added to a flask containing the active ingredient (0.50 g). The contents of the flask were mixed until the active ingredient was dissolved and the resulting solution was sterile filtered into a vial and sealed.

Example 2

Preparation of long-acting injectable formulation containing ivermectin

Following the general procedure of example 1, the following ivermectin formulations were obtained:

number (C)	Drug content% w/v	PLGA content% w/v	Solvent ratio TA/GF	Type of Polymer
					1	10	10	20/80	7525
2	10	10	35/65	7525
					3	10	6.7	50/50	7525
4	10	5	50/50	7525
					5	10	5	50/50	5050

TA ═ triacetin; GF ═ glycerol-formal

For comparison, i.e. to illustrate how much more solvent is used in the present invention compared to the prior art compositions: in formulation 1 of this example, the lipophilic solvent for triacetin is present at about 16.45 wt%. In formulation 2 of this example, the lipophilic solvent for triacetin was present at about 29 wt%. In formulation 3 of this example, the lipophilic solvent for triacetin was present at about 42 wt%. In formulation 4 of this example, the lipophilic solvent for triacetin was present at about 43 wt%.

Example 3

Preparation of long-acting injectable formulations containing an eporinomectin

Following the general procedure of example 1, the following epoetin formulations were obtained:

number (C)	Drug content% w/v	PLGA content% w/v	Solvent ratio TA/GF	Type of Polymer
					1	10	10	50/50	7525
2	5	5	50/50	6535

For comparison, i.e. to illustrate how much more solvent is used in the present invention compared to the prior art compositions: in formulation 2 of this example, the lipophilic solvent for triacetin was present at about 45 wt%. Also, it is noted that the lipophilic solvent may be 100% of the volume of solvent used in the formulation according to the invention, as discussed in the general description above.

Example 4

Long acting injectable formulations containing 6-amino-3-cyano-1- (2, 6-dichloro-4-thiopentafluorophenyl) -4- (trifluoromethylthio) pyrazole active against fleas on dogs

3 beagle dogs were treated with the formulation of example 1 at a single subcutaneous dose of 10 mg/kg. Dogs were fasted for at least 6 hours each before and after treatment. Animals were infested with about 100 fleas on day 1 (day 0 — the day of drug administration). After about 48 hours of infestation, the animals are combed, fleas are checked out and removed. Animals were infested on days 12 and 26, and after about 48 hours of infestation fleas were combed, checked out and removed. Infection/inventorying is repeated approximately one month later.

Blood samples were taken from the animals at 1,2, 3 and 6 hours on day 0 post treatment, at 24 hours on day 1 post treatment, and if emesis was observed. Blood samples were also taken when flea counts were determined. Animals were observed for vomiting every hour after 6 hours of treatment. Demonstrating near 100% efficiency over > 12 months without vomiting in the treated animals. Plasma level curves for each dog are shown in figure 1.

Example 5

Plasma level profile of long-acting ivermectin formulations on cattle

Plasma levels of ivermectin were determined in healthy cattle treated with ivermectin formulations 1,2 and 3 of example 2. Each formulation was administered to 5 cattle at a single subcutaneous dose of 1mg/kg (typically 125-250kg body weight). 10ml heparinized blood samples were taken weekly for each treated animal on days 1-7 (daily), 10, 14 and 15 weeks thereafter. Plasma level curves (average of 5 animals in each group) are shown in figure 2.

Example 6

Plasma level profile of long acting eporinomectin formulations in swine

Plasma levels of epoetin were determined on pigs treated with epoetin formulation 2 of example 3. 3 pigs (inoculated on day-50 with 2,000 eggs of infectious trichuris per se and orally administered on day 0 with 15,000 larvae of infectious nodolonematode species) were injected subcutaneously with formulation 2 of example 3 at a dose of 1.5 mg/kg. Blood samples of 10ml were taken from each animal on days 3,7 and weekly thereafter. The plasma level curve is shown in figure 3 (alternating formulation of drug/PLGA in 100 glycerol-formal).

***

Having described preferred embodiments of the present invention in detail, it is to be understood that the invention defined by the appended claims is not to be limited by particular details set forth in the above description as many apparent variations thereof are possible without departing from the spirit or scope thereof.

Claims (7)

1. A liquid polymer composition for the controlled release of a hydrophobic bioactive material, comprising:

(a) 5-10% of hydrophobic bioactive substance;

(b) 5-10% poly (lactide-co-glycolide) copolymer; wherein the weight ratio of poly (lactide-co-glycolide) copolymer to hydrophobic bioactive substance is from 0.5: 1 to 1: 1, and the copolymer is of a type selected from 7525, 5050 and 6535; and

(c) a mixture of hydrophilic and lipophilic solvents, wherein the volume ratio of hydrophilic to lipophilic solvents is from 20: 80 to 50: 50.

2. The composition of claim 1, wherein the ratio of hydrophilic to lipophilic solvents is from 35: 65 to 50: 50.

3. The composition of claim 1 wherein the biologically active substance is selected from the group consisting of ivermectin, eprinomectin and 6-amino-3-cyano-1- (2, 6-dichloro-4-thiopentafluorophenyl) -4- (trifluoromethylthio) pyrazole.

4. The composition of claim 1, wherein the hydrophilic solvent is glycerol formal.

5. Use of a liquid polymer composition according to claim 1 for the manufacture of a medicament for the controlled release of a hydrophobic biologically active substance in an animal body including a human.

6. A liquid polymer composition comprising:

(a) 5-10% of at least one biologically active substance;

(b) 5-10% of at least one poly (lactide-co-glycolide) copolymer, wherein the weight ratio of polymer to bioactive substance is from 0.5: 1 to 1: 1 and the copolymer is of a type selected from 7525, 5050 and 6535; and

(c) at least one lipophilic solvent or a mixture of at least one hydrophilic solvent and at least one lipophilic solvent, wherein the volume ratio of hydrophilic to lipophilic solvents is from 20: 80 to 50: 50, and/or wherein the lipophilic solvent is present in an amount of at least 16.5 wt%.

7. Use of a liquid polymer composition according to claim 6 in the manufacture of a medicament for the controlled release of a hydrophobic biologically active substance in an animal body including a human.