AUSTRALIA
Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant: SOCIETE DE CONSEILS DE RECHERCHES ET D'APPLICATIONS SCIENTIFIQUES, S.A.S.
POLY-MED INC.
Invention Title: IONIC MOLECULAR CONJUGATES OF BIODEGRADABLE POLYESTERS AND BIOACTIVE POLYPEPTIDES The following statement is a full description of this invention, including the best method of performing it known to me/us: IONIC MOLECULAR CONJUGATES OF BIODEGRADABLE POLYESTERS AND BIOACTIVE POLYPEPTIDES Background of the invention This invention pertains to sustained release of bioactive polypeptides.
Many drug delivery systems have been developed, tested and utilized for is the controlled in vivo release of pharmaceutical compositions. For example, polyesters such as poly (DL-lactic acid), poly (glycolic add), poly (s-caprolactone) and various other copolymers have been used to release biologically active molecules such as progesterone; these have been in the form of microcapsules, films, or rods (Pitt CG, Marks, TA. and Schindler, A. 1980). Upon implantation of the polymer/therapeutic agent composition, for example subcutaneously or intramuscularly, the therapeutic agent is released over a specific period of time.
Such biocompatible biodegradable polymeric systems are designed to permit the entrapped therapeutic agent to diffuse from the polymer matrix. Upon release of the therapeutic agent, the polymer is degraded in vivo, obviating surgical removal of the implant Although the factors that contribute to polymer degradation are not well understood, it is believed that such degradation for polyesters may be regulated by the accessibility of ester linkages to non-enzymatic autocatalytic hydrolysis of the polymeric components.
Several EPO publications and US Patents have addressed issues of polymer matrix design and its role in regulating the rate and extent of release of therapeutic agents in vivo.
For example, Deluca (EPO Publication 0 467 389 A2/Univ of Kentucky)
I
0 describes a physical interaction between a hydrophobic biodegradable polymer and a Sprotein or polypeptide. The composition formed was a mixture of a therapeutic agent Sand a hydrophobic polymer that sustained its diffusional release from the matrix after introduction into a subject.
Hutchinson (US Patent 4,767,628/ICI) controlled the release of a therapeutic agent by uniform dispersion in a polymeric device. It is stated that this formulation V provides for controlled continuous release by the overlap of two phases: first, a cn diffusion-dependent leaching of the drug from the surface of the formulation; and \second, releasing by aqueous channels induced by degradation of the polymer.
o Summary of the Invention According to the present invention there is provided a composition in the form of an implantable rod for drug delivery, comprising: a polyester containing one or more free COOH groups and having a carboxyl to hydroxyl ratio greater than one, wherein said polyester comprises citric acid, E-caprolactone and glycolide, and wherein the ratio of E-caprolactone to glycolide in the polyester is from 90 E-caprolactone 10 glycolide to 99 E-caprolactone :1 glycolide; and one or more bioactive polypeptide comprising at least one effective ionogenic amine, wherein at least 50%, by weight, of the polypeptide present in the composition is ionically conjugated to the polyester.
H: \Mara\Keep\Speci\F5147. ldoc 16/01/06 N 4
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ci The ionic molecular conjugates of the invention are preferably made from polycarboxylic acid-tipped polyesters conjugated with monobasic and potybasic s bioactive polypeptides having at least one effective ionogenic amine group.
C Alternatively, any polyester may be used to form an ionic molecular conjugate of Sthe invention provided it is pretreated with a suitable base, NaOH. Moreover, Sany acid-stable peptide can be used, growth hormone releasing peptide o (GHRP), lutefnizing hormone-releasing hormone (LHRH), somatostatin, bombesin, gastrin releasing peptide (GRP), calcitonin, bradykinin, galanin, melanocyte stimulating hormone (MSH), growth hormone releasing factor (GRF), amylin, tachykinins, secretin, parathyroid hormone (PTH), enkephalin, endothelin, calitonin gene releasing peptide (CGRP), neuromedins, parathyrold hormone related protein (PTHrP), glucagon, neurotensin, adrenocorticotrophic hormone (ACTH), peptide YY (PYY), glucagon releasing peptide (GLP), vasoactve intestinal peptide (VIP), pituitary adenytae cydase activating peptide (PACAP), motiin, substance P, neuropeptide Y (NPY), TSH, and analogs and fragments thereof. Such ionic molecular conjugates are capable of releasing their boactive components in v at predetermined rates determined by the chemical structure, molecular weight, and pKa of both components of these conjugates. A mechanism for the release of the drug entails the transformation of the Insoluble conjugate form to water-soluble components, in part, through the hydrolysis of the hydrophobic polyester. Thus, release of the bioactive polypeptide increases, independently, with the decrease In the pKa differential between the bioactive polypeptide and polyester, the chemical reactivity of the polyester chain that is reflected in the carbonyl nucleophilicity, the decrease in polyester density, as it relates to the glass transition temperature and minimized crystallizability, and (d) the increase in matrix hydrophilicity.
In preferred embodiments the polypeptide comprises 1 to 50 percent by weight of the total weight of the ionic molecular conjugate, and preferably greater than 85%, more preferably 95%, and even more preferably 99%, of the polypeptide present in the composition is ionically conjugated to the polyester; the
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O Spolyester component of the ionic molecular conjugate has a viscosity of about 0.05 to about 0.7 dl/gm in chloroform; and the polyester has an average molecular weight of about 1200 40,000.
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0 (N to In preferred embodiments the polyesterlpolypeptide ionic molecular conjugate is capable of releasing in vivo a therapeutcal effective dose of a bioactive polypeptide over a period of at least 20 days, and more preferably for up to 95 days but not less than 7 days. In yet other preferred embodiments the release of the therapeutic ionic molecular conjugate is essentially monophasic.
The sustained release compositions of the Invention are preferably made by providing a polyester having free COOH groups and a bloadive polypeptide having at least one effective ionogenic amine, and lonically conjugating the polyester to the polypeptide to form an Ionic molecular conjugate, wherein at least by weight, of the polypeptide present in the composition is lonically conjugated to the polyester. The polyester can be one which has sufficient free COOH groups to begin with, or, if an insufficient number of such groups are available for the desired peptide loading level at the outset, the polyester can be reacted with, malic, citric or tartaric add through esterification or functional interchange, or acid-tipped with, glutaric anhydride or the polyester can be treated with a base, NaOH, to expose acid groups. Finally, the polyester/polypeptide ionic molecular conjugate may be converted to implantable films or rods, or injectable microspheres or micropartides capable of releasing in vivo the polypeptide.
I
Preferably, the polyester is synthesized by catalyzing or autocatalyzing direct condensation of one or more hydroxy acids, glycolic add and lactic acid, in the presence of a predetermined concentration of a polycarboxylic hydroxy acid, malic add, citric acid or tartaric acid. The polyesters thus formed s possess acid-tipped hydroxyl end groups which are preferably partially or fully acid-tipped.
The polyesters also can be synthesized by catalyzing ring-opening polymerization of lactones, or by polymerization of cyclic monomers such as ecaprolactone, p-dioxanone, trimethylene carbonate, 1,5-dioxepan-2-one, or, 1,4- 1o dioxepan-2-one in the presence of a chain initiator, a hydroxy polycarboxylic add.
Another method of synthesizing involves reacting a hydroxy add with a cyclic dimer, followed by condensation of the open chain system in the presence of a polycarboxylic acid.
Yet another synthetic method involves reacting an organic polycarboxylic add with a preformed polyester.
-In the aforementioned preferred embodiments the acid-tipped polyester has a carboxyl to hydroxyl end group ratio of more than one and approaching infinity eliminating all the hydroxyl groups) with an average degree of polymerization between 10 and 300, and in particularly preferred embodiments between 20 and Alternatively, a polyester is rendered capable of forming an ionic molecular conjugate with a bioactive polypeptide by treatment with a base, e.g, NaOH.
Preferably, the polyester/polypeptide ionic molecular conjugate is synthesized by direct interaction between the polyester, in the free form, and the polypeptide, in the free form, in the proper liquid medium. In other preferred embodiments suitable solvents for the formation of the conjugate would be a mixture aprotic solvent acetone, tetrahydrofuran (THF), or ethylene glycol dimethylether] and a suitable solvent for the peptide water) in proportions such that the two systems are miscible. Preferably, the polypeptide is a salt of a monocarboxylic acid having a pKa greater than or equal to Preferably, the polypeptide has at least one effective ionogenic amine group.
O In preferred embodiments the polypeptide is 1 to 50 percent by weight, and Spreferably 10 to 20 percent of the polyester/polypeptide ionic molecular conjugate. In Spreferred embodiments, the accessible carboxyl groups of the polyester are partially neutralized with alkali metal ions or organic bases. In yet other preferred embodiments, the alkali treatment provides chain dissociation of the polyester and formation of lower molecular weight binding sites.
in) A preferred polyester is where the ratio of E-caprolactone to glycolide in the 0 c polyester is 97 E-caprolactone 3 glycolide.
\O A preferred embodiment of the composition is where the bioactive polypeptide is selected from the group consisting of LHRH, somatostatin, bombesin/GRP, Scalcitonin, bradykinin, galanin, MSH, GRF, H:\Mara!\Keep\Speci\P5144 .doc lc/01/0 -8-
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Samylin, tachykinins, secretin, PTH, CGRP, neuromedins, PTHrP, glucagon, c neurotensin, ACTH, GHRP, GLP, VIP, PACAP, enkephalin, PYY, motilin, substance SP, NPY, TSH, and analogs or fragments thereof.
A preferred embodiment of the immediately foregoing composition is where the bioactive polypeptide is selected from the group consisting of LHRH, somatostatin and analogs or fragments thereof.
th A preferred embodiment of the immediately foregoing composition is where Cc the LHRH analogue is of the formula pGlu-His-Trp-Ser-Tyr-D-Trp-Leu-Arg-Pro-Gly-
NH
2 and the somatostatin analogue is of the formula H 2 N-p-D-Nal-Cys-Tyr-Trp-Lys- 10 Val-Cys-Thr-NH 2 wherein the two Cys residues of the somatostatin analogue are Sbonded to each other.
C A preferred embodiment of the composition is where the rod has a coating of a polyester.
A preferred embodiment of the immediately foregoing composition is where the polyester coating the rod is an absorbable polyester.
A preferred embodiment of the immediately foregoing composition is where the absorbable polyester contains one or more free COOH groups and having a carboxyl to hydroxyl ratio greater than one, wherein said polyester contains a member selected from the group consisting of L-lactic acid, D-lactic acid, DL-lactic acid, malic acid, citric acid, tartaric acid, E-caprolactone, p-dioxanone, E-caproic acid, alkylene oxalate, cycloalkylene oxalate, alkylene succinate, p-hydroxybutyrate, substituted or unsubstituted trimethylene carbonate, 1,5-dioxepan-2-one, 1,4-dioxepan- 2-one, glycolide, glycolic acid, L-lactide, D-lactide, DL-lactide, meso-lactide, and any optically active isomers, racemates or copolymers thereof.
A preferred embodiment off the immediately foregoing composition is where the polyester comprises citric acid, E-caprolactone and glycolide.
A preferred embodiment of the immediately foregoing composition is where the absorbable polyester coating the rod is the same as the polyester comprised in the composition.
"Polypeptide", as used herein, refers to a protein, peptide, oligopeptide or synthetic oligopeptide.
"Polycarboxylic", as used herein, refers to compounds having more than one carboxyl gropu, eg., malic acid, citric acid and tartaric acid.
"Average degree of polymerization", as used herein, refers to the number of repeat monomer sequences.
H: \NIara\Keep\Specl\F51447.doc 1/01/06 "Effective ionogenic amine", as used herein, refers to a polypeptide that contains at least one amine group capable of forming an ion under prevailing conditions.
"Acid-tipped", as used herein, refers to compounds having an acid s terminus.
"Partially add-tipped", as used herein, refers to compounds having 1 99 percent of their hydroxyl end groups acid-tipped.
"Fully add-tipped", as used herein, refers to compounds having greater than 99.9% of their hydroxyl groups acid-tipped.
"Hydroxy acids", as used herein, refers to any compound containing hydroxyl and carboxyl groups.
"Monocarboxylic hydroxy acid", as used herein, refers to an organic acid with one carboxyl group and one or more hydroxyl group.
"Polycarboxylic hydroxy acid", as used herein, refers to a hydroxy acid with more than one carboxyl group.
"Organic entrainer", as used herein, refers to organic liquids which codistill with water.
"Bioactive", as used herein, refers to a molecule that elicits or affects a biological event.
"Acyclize", as used herein, refers to a chemical reaction that occurs by ring opening.
"Polycondensation", as used herein, refers to the formation of a polyester by the condensation of two or more molecules.
"Absorbable" polyester, as used herein, refers to a water insoluble polyester which undergoes chain disassociation in the biological environment to water soluble by-products.
The present invention provides a new pharmaceutical composition that chemically bonds a biocompatible, biodegradable polyester to oligopeptides, polypeptides, peptides and or proteins as a homogeneous ionic species. By chemically bonding polyesters of different molecular weights to the therapeutic agents, the chemical characteristics of the composition can be more precisely tailored to meet the demands for the controlled monophasic release of the biologically active polypeptide molecule in vivo. Furthermore, the compositions of the invention are optimized easily to possess functional properties for greater loading of a therapeutically active polypeptide.
Other features and advantages of the invention will be apparent from the s following detailed description of the preferred embodiments, and from the claims.
Brief Description of the Drawings Figure 1 is an illustration representing isomers of polycarboxylic acidtipped lactidelglycolide (malic type) copolymer.
Figure 2 is an illustration of an ionic molecular conjugate depicting the chemical interactions between the lactide/glycolide (malic type) copolymer and Somatuline (BIM-23014).
Figure 3 is a graph depicting the percent peptide released from ionic molecular conjugates into PBS buffer at 37°C over a 28-day period.
Description of the Preferred Embodiments is Synthesis The biodegradable or absorbable polyesters of the invention are tailored to possess the desired chemical reactivity to provide controlled chain hydrolyzability and exhibit maximum binding capacity to oligopeptides, polypeptides or proteins having a net positive charge at physiologic pH, by the proper selection of the constituent monomers, co-monomers or comers to form chains with predetermined compositions and molecular weights.
A tripartite synthetic design, within the ability of someone of ordinary skill in this field, is employed to prepare the compositions of the present invention. The steps include: synthesis of the polycarboxylic acid-tipped polyesters; (2) synthesis of the polyester/polypeptide ionic conjugate by ionic interaction of polycarboxylic acid-tipped polyesters (or a polyester treated with a base) and biologically active polypeptides; and conversion of ionic conjugates to implants, rods, microspheres or micropartides capable of releasing in vivo the therapeutic agent for at least 7 days.
Synthesis of polycarboxylic acid-tipped polyesters The polycarboxylic acid-tipped polyester chains of the invention are synthesized by methods such as direct condensation of a 2-hydroxy acid and a polycarboxylic organic acid, step-growth polymerization of acyclized products, ring-opening polymerization of a lactone or a lactone mixture, or functional interchange of a polycarboxylic organic acid with preformed high molecular weight polyesters (See Fig. 1) Descriptions of the synthesis of polycarboxylic acid-tipped s polyesters by these aforementioned methods follow.
Direct condensation of 2-hydroxy acids in an optically active and/or an inactive form and a predetermined amount of a polycarboxylic organic acid in the presence or absence of inorganic, or organometallic catalyst, condensation of glycolic acid DL-lactic acid, and DL-malic add is generally accomplished by lo heating the monocarboxylic hydroxy acids or mixture of two or more monocarboxylic hydroxy acid in the presence of a fraction of polycarboxylic hydroxy add in a glass reactor equipped for providing a continuous flow of drynitrogen and mass agitation (designated Type IA Polyester, see Table 1).
Typically, the polycondensation is conducted at 150-170C for 4 to 72 hours.
Agitation of the reaction mixture can be provided by a magnetic stirrer or bubbling the nitrogen gas through the polyester mass. The polymerization is continued until the desired average molecular weight (determined in terms of solution viscosity) and/or add number (determined by end group titration) is achieved. Polyester analysis by end group titration is performed as follows. Polyester samples (300 2o mg-500 mg) are accurately weighed and dissolved in a minimal amount (10-30 ml) of acetone. After dissolution, the solutions are diluted to 100 ml with benzyl alcohol (Mallinckrodt, Analytical Reagent) and titrated to a faint pink end-point (phenolphthalein) using potassium hydroxide in benzyl alcohol solution (Normalized vs. HCI Standard). The volume of base solution used for the sample (AVs) is compared with the volume of base used for a solvent blank (AVo) to determine the acid number for the polyester.
Acid Wt. of Sample (mq) {AVs(ml) AVo(ml)} x N of Base At the conclusion of polymerization, the polyester is isolated and extracted with water or a dilute aqueous sodium hydroxide solution, from a suitable organic solution to remove water-soluble or solubilizable low molecular weight chains.
Polyester analysis by GPC is performed as follows. The average molecular weights (MW) of polyester were determined by GPC using a Waters Model 6000 solvent delivery pump and a Dynamax (Rainin) model UV-D detector.
Runs were performed in tetrahydrofuran (Burdick Jackson UV grade) using a Jordi Gel DVB 1000A, 50cm x 10 mm column (Jordi Associates) at a flow rate of 1.2 ml/min at 25 Peak detection was at 220 nm and 1.0 AUFS. The column was calibrated using narrow band polystyrene reference standards (Polysciences Inc.) at Mw 4000, 9,200 and 25,000.
A modification of the direct condensation process entails the use of an organic entrainer and a cationic exchange resin as a condensation catalyst (designated Type IB Polyester, see Table This process requires a filtration and evaporation step to remove the catalyst and entrainer, respectively. Typical examples of polyesters made by these processes and pertinent analytical data are described in Table I.
TABLE I: POLYESTERS MADE BY DIRECT CONDENSATION METHOD Type IA Polyesters Polymer Polymerization Charge Conditions Acid Tg, C 1 L-Lactic Acid 35.7 gm (0.349M) 100*C/0.7 hr 563 0.24 11 Glycolic Add 4.65 gm (0.612M) 1650C/17.5 hrs Citric Acid 1.75 gm (0.0091M) 2 L-Lactic Acid 25.6 gm (0.25M) 165*C/22 hrs 820 0.14 27 Glycolic Acid 19.2 gm (0.25M) Malic Acid 1.5 gm (0.011M) Type IB Polyesters 3 L-Lactic Acid 25.6 gm (0.25M) 132rC/53 hrs 842 Glycolic Acid Citric Add Amberlyst Catalyst Beads #15 Toluene 4 L-LacticAdd (88%) Glycolic Acid Malic Acid Ambertyst Toluene 19.2 gm (0.25M) 2.13 gm (0.011M) 0.5 gm 150ml Using Dean-Stark Trap. Decanted, filtered in Acetone. Dried.
Washed with water. Vacuum dried.
25.6 gm (025M) 132C/68 hrs 1421 19.2 gm (0.25M) 1.5gm (0.01.1M) Using Dean-Stark Trap. Decanted.
100 ml Filtered, Dried.
Washed with water and Vacuum Dried.
"Determined on a differential scanning calorimeter (TA 2100 DSC) using 2-10 mg sample and heating rate of 10°C/min in a nitrogen atmosphere Step-growth polymerization of acyclized products, where a hydroxy acid is allowed to react with cyclic dimers and subsequent condensation of the resulting open chain system in the presence of predetermined amounts of a polycarboxylic acid and the presence or absence of a suitable condensation catalyst e.g. glycolic acid, L-lactide and DL-malic acid, essentially the same as the condensation process described above, except that it employs a mixture of a monocarboxylic hydroxy-acid, a cyclic dimer of a second hydroxy-acid, and a hydroxy polycarboxylic acid. Examples of polyesters made by this process and pertinent analytical data are summarized in Table II. When the cyclic dimer is pretreated with water the system is treated as a simple step-growth polymerization.
TABLE II: STEP-GROWTH POLYMERIZATION OF ACYCLIZED PRODUCTS Type II Polyesters Polymer Polymerization Acid Charge Conditions th, Tg,°C' 1 L-Lactide Monomer 10.0 gm (0.07M) 160*°C29 hrs 1200 021 Glycolic Add 10.7 gm (0.14M) Malic Aid 0.79 gm (0.0061M) 2 L-Lactide Monomer 20.0 gm (0.139M) 25C-155 0 C/1.5h 1800 0.13 27 Glycoc Acid 7.1 gm (0.093M) 155C/70 hr Malic Add 1.01 gm (0.0075M) Dissolve in DCM wash with water, and dry in vacuo.
"Determined on a differential scanning calorimeter (TA2100 DSC) using 2-10 mg sample and heating rate of 10°C/min in a nitrogen atmosphere Ring opening polymerization of a lactone or lactone mixture in the presence of a predetermined concentration of hydroxy-polycarboxylic acid as a chain initiator and a catalytic amount of an organometallic catalyst e.g. a mixture of L-lactide, glycolide and DL-malic acid in the presence of stannous octoate employs dry cyclic monomers or a mixture of cyclic monomers, a hydroxypolycarboxylic acid and a trace amount of stannous octoate (used as 0.33M solution in toluene), which are transferred under a dry oxygen-free atmosphere into a glass reactor equipped for magnetic or mechanical stirring. The polymerization reaction is continued under nitrogen following a suitable heating scheme until the desired molecular weight is achieved (as measured in terms of solution viscosity). At the conclusion of the polymerization scheme, the temperature is lowered and the unreacted monomer is distilled under reduced pressure. The polyester mass is then cooled and the water-soluble low molecular s weight fractions are removed by low temperature extraction from a suitable organic solution. The solution is then dried and the solvent is removed. The molecular weight is then determined in terms of inherent viscosity and the add number is determined by end-group titration. Examples of polyesters prepared by this process and pertinent analytical data are given in Table Ill.
TABLE Ill: POLYESTERS MADE BY RING OPENING POLYMERIZATION Type II Polyesters Polymer Polymerization Acid Charge Conditions 11h Tg,D°C 1 Glycolide L-Laclide Malic Add 2 Glycolide D,L-Lacide MalicAcid 3 Glycolide D,L-Lacide Cic Acid 4 Glycolide D.L-Lactide Malic Acid Glycolide D.L-Lactide 1,6-hexanediol 3.22 gm (0.028M) 10.7 gm (0.14M) 0.79gm (0.0061M) 2.84 gm (0.0245M) 20.0 gm (0.139M) 0.876 gm (0.00541M) 2.84 gm (0.0245M) 20.0 gm (0.139M) 1.256 gm (0.00654M) 8.06 gm (0.0694M) 10.0gm (0.0694M) 0.744 gm (0.00555M) 8.06 gm (0.0694M) 10.0 gm (0.0694M) 0.656 gm (0.00555M) 120*C/0.5 hr 1500C/6 hr 120"C/11 hrs 120C/0.5 hr 180 0 aC2.5 hrs 130C/15 hrs 155°C/1 hr 185"C/2.5 hrs 190*C/2.5 hrs 160*C/13 hrs 180*C/1 hr 185*C/2 hrs 195°C/7 hrs 120'C/9 hrs 150°C/0.5 hr 185"C/4 hrs 150°C/1.5 hrs 120C/3 hrs 2.150 0.79- 38 1.206 0.08 26 937 0.10 27 970 0.26 23 10,138 0.39 Determined on a differential scanning calorimeter (TA2100 DSC) using 2-10 mg sample and heating rate of 10°C/min in a nitrogen atmosphere In hexofluoroisopropanol Functional interchange of polycarboxylic or hydroxy-polybasic organic acid with preformed high molecular weight polyesters with COOH/OH ratio of unity to virtually zero, preferably in the presence of an organometallic catalyst, e.g. melts reaction of an 85/15 lactide/glycolide copolymer with a molecular weight greater than 5,000 and COOH/OHsl with DL-malic acid in the presence of stannous octoate, to produce the lower molecular weight polyesters with COOH/OH1, entails heating a high molecular weight polyester with a predetermined amount of polycarboxylic or hydroxy-polycarboxylic acid in the presence of a trace amount an organometallic catalyst such as stannous octoate. The reactants are heated above 150 0 C under dry nitrogen with intensive agitation until the functional interchange is completed (as measured by depletion of residual unreacted polycarboxylic acid). In effect this is determined by monitoring the molecular weight (in terms of solution viscosity using capillary viscometry at 28 0 C) of the is resultant lower molecular weight polyester and the presence of unreacted polycarboxylic add. This is achieved by aqueous extraction of a polyester sample and analysis of the extract using high performance liquid chromatography (HPLC).
Residual monomer, dimer and polycarboxylic add levels were determined by HPLC using a Waters Model 6000 solvent delivery pump and a Dynamax (Rainin) model UV-D detector (205 nm, 1.0 AUFS). Runs were performed using 0.025N NazPO 4 buffer, pH 3.5 (isocratic flow rate 1.0 mi/min.) using a Nuceosil C18, um, 25 cm x 4.6 mm column.
The desired polyester is isolated and purified as described above for ringopening polymerization. An example of a polyester made by this process and pertinent analytical data are given in Table IV.
TABLE IV: POLYESTERS MADE BY FUNCTIONAL INTERCHANGE Type IV Polyesters Polymer Polymerization Acid Charge Conditions linh Tg,"C' 1 Boehringer A001 8 gm (50/50 dl-Lactide/Glycolide) 150°C/5 hrs 670 0.26 Citric Acid" 0.8 gm (0.00417M) 'Determined on a differential scanning calorimeter (TA2100 DSC) using 2-10 mg sample and heating rate of 10*C/min in a nitrogen atmosphere "A catalytic amount of stannous octoate (2 drops of 0.33 M solution, approximately 0.03 nmole).
Among the other monomers suitable for the synthesis of the polyesters used in the invention are: L-lactic acid, DL-lactic acid, e-caprolactone, pdioxanone, e-caproic acid, trimethylene carbonate, 1,5-dioxepan-2-one, 1,4dioxepan-2-one, glycolide, and meso-lactide. Examples of useful polycarboxylic chain initiators and/or chain modifiers include malic acid, citric acid and tartaric acid.
Synthesis of the polyesterlpolypeptide Ionic conjugate by Ionic interaction of polycarboxylic acid-tipped polyesters and biologically active polypeptides.
The polycarboxylic acid-tipped biodegradable polyesters described above are used to make an ionic molecular conjugates with mono- or polycarboxylic oligopeptides, polypeptides or proteins with accessible effective ionogenic amine groups (see Fig. Moreover, any polyester is rendered capable of forming an ionic molecular conjugate with a polypeptide provided it is treated with a base, 0.1N NaOH. Such treatment exposes acid groups of the polyester for multiple site ionic interaction with the cationic polypeptide.
Thus, the formation of these conjugates is achieved by direct molecular interaction of the components in the proper solvent with or without a pretreatment 18 of the polyester with an inorganic base to maximize its binding rate capacity to the basic drug. As noted above, the ionic interaction of their ionic conjugate components increases within the difference in their pKa values.
The polyester is dissolved in a suitable aprotic solvent in a concentration range of 2% to 20% WN. Such solvents should dissolve the polyesters, but also be partly miscible with water. Suitable solvents used for this purpose include tetrahydrofuran, acetone, and ethylene glycol dimethylether. To this solution, an aqueous solution of base such as sodium, potassium or ammonium hydroxide or carbonate is added to maximize the binding capacity of the polyester. In general, a o the amount of base added corresponds to the amount of acid represented by the counter-anion level of the basic peptidle to be used.
After briefly mixing the polyester-base combination, an aqueous solution of peptide or peptide salt is added at peptidlelpolyester loading levels of 2% to W/W (peptidelpolyester). This mixture is stirred for a period of time (up to 3 is hours), and then the solvents are removed and the product is dried under vacuum.
The resulting material may then be further processed for dosage formulation. The resulting pharmaceutical compositions are designed to be chemically uniform compositions made totally of ionic molecular conjugates and are essentially devoid of microscopically or macroscopically dispersed domains of the active drug in the biodegradable matrix. Examples of prepared ionic molecular conjugates and pertinent analytical data are given in Table V.
TABLE V: IONIC MOLECULAR CONJUGATE-PEPTIDE BINDING 1 Polymer Used Peptide 2 Loading Retention 3 1 50/50 dl LactideGlycolide 1 10 47 (Commercial) 1 20 Acid 22,000 11 20 73 qinh 0.53 11I 20 48.5 2 Poly L-Lactide 1 10 62 (Commerciar) 11 20 Mw (ave) 2,000 Acid 850 3 Poly L-Lactide I 10 54 (Commercial) Mw (ave)= 50,000 Acid 2100 4 48/48/4 Poly d1-Lactidel I 20 43 Glycolide/1,6 hexanediol (Method 111) Acid 10,138 'Inh 0.39 49/49/2 Poly L-Lactict 1 10 100 GlyomflcMaic Acid I 20 99 (Type IB) 1 30 95.5 Acid 1400 I 40 96.0 ratnh 0 20 1 50 99,8 II 20 99.8 III 20 77.5 6 83.3/14.7/2 Poly L-Lactic/ 1 20 96 GlycolicCitric Acid (Type A) Add =563 ninh= 0.
24 7 49/49/2 Polyd,1-Lactide I 20 96 Glycolide/Malic Acid (Type II) III 20 73.9 Acid 1200 Tlinh= 0.21 8 48/48/4 Poly d,1-Lactide/ 1 10 GlycolideCibtric Acid (Type Ill) Acid 589 Tlinh= 0.
22 1 In all cases, conjugates were formed as outlined in text using acetone as solvent and sodium hydroxide as base. AJll peptides used were in the acetate salt form.
2 Peptides: 1 BIM-21003 -Trp6-LHRH(pGlu-His-Trp-Ser-Tyr-D-Trp-Leu-Arg-Pro-Gly
NH
2 pka 10.1 11 BIM-23014 (H2N-D-Nal-Cys-Tyr-Trp-Lys-Val-Cys-Thr
NH
2 pka 9.8 III BIM-26226 (H 2
N-D-F
5 Phe-GIn-Trp-Ala-Val-D-Ala-His-Leu-OCH 3 pka 3 Retention: Measured by rinsing the dried polyester/peptide ionic conjugates with 0.1. water and quantitating soluble peptide in rinses by HPLC WL Peptide Loaded WL Soluble Peotide Retention 100% x Wt. Peptide Loaded Conversion of ionic conjugates to Implants, rods, microspheres or microparticles capable of releasing in vivo the therapeutic agent for at least days in a monophasic profile. The ionic conjugate salts of the invention can be converted to: sterile injectable microspheres (with or without 0.1 to 10% of a s solid polyhydric alcohol as processing aid) containing 1 to 50% by weight polypeptide that can be released according to an essentially monophasic profile and to sustain pharmacological activity over a period of one to 12 weeks; (B) sterile implantable films made by casting, pressing or extrusion with or without a pharmacologically inactive processing aid, and capable of providing a release profile similar to that described in and; sterile injectable rods made by extrusion or pressing, capable of providing a release profile similar to that described in Further, rods can be coated with a polyester to provide an additional layer of control over the rate of release of a therapeutic agent.
Preferably, the rods are coated with an absorbable polyester, more preferably the is absorbable polyester is as defined herein and most preferably the coating absorbable polyester is the same as the polyester comprised in the rod.
In-Vitro Release Assay: Samples of the dried and ground ionic conjugate material weighing 50 mg each were placed in 25 mm diameter scintillation vials. A 5 ml aliquot of modified PBS buffer (PBS buffer: 287 gm Na 2 HPO0, 0.654 gm NaH 2 PO,, 5.9 gm NaCI. 0.5 gm NaN,, Q.S. 1.0 Liter with Deionized water; pH 7.27.) was added to each vial and the vials were placed in a Lab-Une Orbit Environ-Shaker and swirled at 120 R.P.M. and 37°C. Vials were withdrawn periodically and decanted and replenished with fresh PBS solution. The amount of released peptide was determined from the decanted PBS solutions by HPLC.
Peptide Extraction From Ionic Conjugates: A 50 mg sample of an ionic molecular conjugate was mixed into 20 mis of methylene chloride. The mixture was sequentially extracted with 50 ml, 20 ml and ml portions of 2N acetic acid. The acetic acid extracts were combined and analyzed for peptide content by high performance liquid chromatography (HPLC).
Peptide analysis by HPLC is as follows. HPLC analysis were performed using a Waters model M-45 solvent delivery pump and an EM Science MACS 700 detector at wavelength 220 nm and 1.0 AUFS. Peptides were run using a Lichrospher (EM separations) C18,100A, 51m, 25cm x 4.6 mm column and acetonitrile/0.1% TFA as an isocratic eluent buffer.
Following are details (Table VI) of the in vitro assay demonstrating the amount of peptide released over a 28 day period for 49:49:2 L- Lactic/Glycolic/Malic\D-Trp[LHRH] (Example 49:49:2:L- Lactic/Glycolic/Malic\Somatostatin-Tumor Inhibiting Analogue (Example and 73.5:24.5:2 poly-L-lactide/glycolic/Malic:D-Trp [LHRH] (Example #10) ionic molecular conjugates.
TABLE VI IN-VITRO ASSAY DATA DAY OF ASSAY PERCENT OF TOTAL PEPTIDE RELEASED Example #8 Example #9 Example 1 5.5% 12.5% 11% 7 26.9% 21.3% 53% 14 55.2% 47.3% 17 84.4% 72.2% 21 98.6% 82.5% 66% 24 100% 98.2% 28 99.6% Quantitation of Peptides in Ionic Conjuqates lonically bound peptides in the conjugate products were measured by dissolving 10 mg of sample in 5.7 ml of a 9:1 mixture of acetone and 0.1M aqueous trifluoroacetic acid. The solutions were swirled at about 25 C for about 15-24 hours and then filtered through 0.5 pm teflon filter cartridges. The filtrates were then analyzed for peptide content by high performance liquid chromatography (HPLC). Peptide analysis by HPLC were run using a Millipore model 717 Wisp Autosampler, a model 510 pump and a model 486 UV detector set at 220nm. Peptides were run on a Lichrospher (EM Separations) 25 cm x 4.6
I
mm C18, 5 pm 100A column, flow rate 1.0 ml per minute using 35% acetonitrile in 0.14% sodium perchlorate buffer as an isocratic eluent system. Peptides were quantified by comparison of the area of the correct peak in the sample run with the area of a injected peptide standard.
s Use Any of the acid-bearing polyesters/polypeptide ionic conjugates described herein can be administered to a recipient alone or in combination with a pharmaceutically-acceptable medium. Although it may be convenient to administer subcutaneously, intramuscularly, parenterally, by suppository or to nasally, the therapeutic preparation is administered in accordance with the condition to be treated. The concentration of the composition in the formulations of the invention will vary depending upon a number of issues, including the dosage to be administered, and the route of administration.
Without further elaboration, it is believed that one skilled in the art can, is using the preceding description, utilize the instant invention to its fullest extent.
The following embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever.
EXAMPLE 1 DIRECT CONDENSATION METHOD Synthesis of 50150 Poly (D,L-Lactic-co-glycolic) catalyzed by Amerlyst D,L-lactic acid (85% aqueous mixture; 13.7 gm, 0.13 mole) was mixed with glycolic acd (10 gm, 0.13 mole) in a round bottom flask fitted with a magnetic stirrer, a Dean-Stark trap and a water cooled condenser. Toluene (100 ml) and Amberlyst 15 beads (100 mg) were added and the mixture was refluxed under nitrogen for 72 Hours, removing water from the mixture. The mixture was cooled, toluene was decanted from the solidified mass and the product was dissolved in methylene chloride (250 ml). The methylene chloride solution was treated with activated charcoal (Darco. 500 mg), filtered and vacuum dried in a rotary evaporator. The polyester was further dried under high vacuum (1 mm Hg) at 40OC to afford a white powder. (Ti in CHCI, 0.3, Acid 2439, Tg 12 0
C)
EXAMPLE 2 DIRECT CONDENSATION METHOD Synthesis of 49149/2 Poly(L-Lactic-co-glycoliclcitric) catalyzed by Amberlyst Using a system similar to above, L-lactic acid (88% aqueous mixture; 25.6 gin, 0.25 mole) was combined with glycolic acid (19.2 gm, 0.25 mole), citric acid s monohydrate (2.33 gin, 0.011 mole), Amberlyst 15 beads (500 ing) and toluene (150 ml) in a round bottom flask. The mixture was heated with stirring to reflux for 51 hours, removing water by the Dean-Stark trap. The toluene was decanted from the semi solid product. The polyester was dissolved into acetone (300 ml) and filtered and dried on a rotary evaporator. The solid polyester was then redissolved lo in methylene chloride and was washed twice with water (2 x 150 ml) to remove soluble oligorners. The organic solution was concentrated on a rotary evaporator and the product was thoroughly dried under vacuum to afford a white solid (see Table 1, Type IB Polyester, Polymer (qh in CHC1 3 0.11, Acid 842, Tg 15 0
C)
is EXAMPLE 3 STEP GROWTH POLYMERIZATION METHOD Synthesis of 73.5124.5/2 Poly(L-Lactide-co-glycolic/mallc) catalyzed by malic acid.
Using a 150 ml capacity cylindrical ampule with an air impinger fitting Llactide (20 gm, 0.139 mole) was combined with glycolic acid (7.1 gin, 0.093 mole) 2o and (d,I)-malic acid (1.0 gm, 0.0075 mole). The mixture was agitated by bubbling nitrogen through the impinger inlet (100 ml/min) and heated from 25°C to 155 0
C
over 100 minutes. The reaction temperature was maintained at 155 0 C for hours and the water from polymerization was removed in a cold trap on the reactor outlet line. After 70 hours the reaction was cooled to 1000C and poured 2s into a chilled stainless steel receiver for hardening. The solid polyester was then dissolved in methylene chloride and was washed twice with water (2 x 150 ml) to remove soluble oligomers. The organic solution was concentrated on a rotary evaporator and the product was thoroughly dried under vacuum to afford a white solid (see Table II, Type II Polyester, Polymer (qinh in CHCIG 3 0.13. Acid 1800, Tg 27 0
C)
EXAMPLE 4 RING OPENING POLYMERIZATION METHOD Synthesis of 75125 poly(L-lactide-co-glycolide) initiated by malic acid.
L-lactide (12.0 g, 0.0833 mole), glycolide (3.21 g, 0.0277 mole), malic add 0.3042 g, 0.00227 mole), and stannous octoate catalyst (0.33 M in toluene, 67 jL, s 0.022 mmole) were added under dry nitrogen conditions to a glass ampule with a magnetic stirrer. The system was purged with N, and evacuated with vacuum several times before sealing the ampule. The reactants were then melted at 140 0 C and the melt.was heated at 1800, 1900, 1800, and 1500 for 1, 4.5, 12, and 2 hours, respectively. After cooling to room temperature, the polyester was 1o reheated to 110°C under a vacuum of less than 1 mm Hg for about one hour to remove monomer, recooled at room temperature, quenched in liquid nitrogen, isolated and dried under vacuum. (nTin CHCI, 0.20, Acid 2560, Tg 39C) EXAMPLE 5 -RING OPENING POLYMERIZATION METHOD- Synthesis of 50150 poly(D,L-lactide-co-glycolide) initiated by citric acid.
D,L-lactide (10.0 g, 0.0694 mole) was mixed with glycolide (8.06 g, 0.0694 mole), citric acid (1.07 g, 0.00555 mole) and stannous octoate catalyst (0.33 M in toluene, 84 pL, 0.0278 mmole) under a dry nitrogen atmosphere in a glass ampule containing a magnetic stirrer and sealed under vacuum. The reactants were melted and heated at 180", 1850, 1950, and 120°C for 1, 2, 7, and 9 hours, respectively. The polyester was cooled to room temperature, quenched in liquid nitrogen, isolated, and dried.
CHCI
3 0.26, Acid 970, T, 23"C) EXAMPLE 6 -RING OPENING POLYMERIZATION METHOD Synthesis of 50/50 poly(D,L-lactide-co-glycolide) initiated by 1,6-hexanediol.
Using a system similar to those described above, D,L-lactide (10.0 g, 0.0694 mole), glycolide (8.06 g, 0.0694 mole), 1,6-hexanedio (0.656 g, 0.00555 mole), and stannous octoate (0.33 M in toluene, 84 iL, 0.0278 mmole) were added under dry nitrogen conditions to a glass ampule which was subsequently sealed under vacuum. The constituents were heated at 1500, 185°, 150°, and 120°C for 0.5, 4, 1, 5, and 3 hours, respectfully. The resulting polyester was recovered and dried (see Table Ill, Type III Polyester, Polymer (rlhin CHCI, 0.39, Acid 10,138, T, 30 0
C)
EXAMPLE 7 FUNCTIONAL INTERCHANGE METHOD Synthesis of carboxylic-bearing 50/50 poly(D,L-lactide-co-glycolide).
50/50 poly(D,L-lactide-co-glycolide) (Boehringer A001, 8 citric acid (0.8 g, 4.16 mmole), and stannous octoate (2 drops) were added to a glass s ampule under dry nitrogen conditions and sealed. The mixture was heated at 1500 for 4 hours, cooled to room temperature, quenched in liquid nitrogen, isolated, and dried (see Table IV, Type IV Polyester, Polymer (Thin CHCI 3 0.26, Acid 670, T, 23 C) EXAMPLE 8 Synthesis of a 49:49:2 L-LacticlGlycoliclMalic (See Table I, Polymer and D-Trp' [LHRH] ionic molecular conjugate.
500 mg of 49:49:2 L-Lactic/Glycolic/Malic (synthesized by direct condensation; Mw 9,500; Acid# 1420) was dissolved in 10 mis of Acetone (Mallinckrodt Analytic Reagent). A portion of 0.1N sodium hydroxide solution (1.14 ml) was added and the mixture was stirred at room temperature for minutes. A solution of 100 mg of D-Trp* [LHRH] (BIM-21003 Peptide I; base content 87%, acetate content in 1.0 ml water was added and the mixture was stirred for 1 hour at room temperature. The solvents were then removed, first by Rotovap at T<40*C and then in a desiccator for 1 hour at room temperature under 1 mm Hg vacuum. The dried solid was triturated and stirred in 100 mis of deionized Water and isolated by filtration. The aqueous filtrate was tested by HPLC and found to contain <1 mg soluble peptide. The solid material was dried several days in vacuo to give 540 mg of white powder. The powder was used in an in vitro assay (see Table VI, Example EXAMPLE 9- Synthesis of a 49:49:2 L-lactic/glycolic/malic, see Table I, polymer and Somatostatin/Tumor Inhibiting Analogue ionic molecular conjugate.
100 mg of 49:49:2 L-Lactic/Glycolic/Malic (synthesized by direct condensation; Mw 9,500; Acid 1420) was dissolved in 2mis of acetone (Mallinckrodt Analytic Reagent). A portion of 0.1N sodium hydroxide solution (0.32 ml) was added and the mixture was stirred at room temperature for minutes. A solution of 20 mg of Somatostatin/Tumor Inhibiting Analogue (BIM- 23014 Peptide II; base content 83%, acetate content in 1.2 ml water was added and the mixture was stirred for 1 hour at room temperature. The solvents were then removed, first by Rotovap at T<40 0 C and then in a desiccator for 1 hour at room temperature under 1 mm Hg vacuum. The dried solid was triturated and stirred in 20 mis of Deionized Water and isolated by filtration. The s aqueous filtrate was tested by HPLC and found to contain <0.05 mg soluble peptide. The solid material was dried several days in vacuo to give 106 mg of white powder. The powder was ground and used in an in vitro release assay (see Table VI, Example EXAMPLE 10 Synthesis of a 73.5:24.5:2 poly L-lactidelglycolic/malic (see 0o Table II, see polymer and D-Trp' [LHRH] ionic molecular conjugate.
800 mg of 73.5:24.5:2 poly L-lactide/glycolic/malic (synthesized by step growth of acyclized products; Acid# 1800) was dissolved in acetone (16 ml). A portion of 0.1N sodium hydroxide solution (2.8 ml) was added and the solution was stirred at room temperature for 20 minutes. A solution of 200 mg of D-Trp" is [LHRH] (BIM-21003; base content 87%, acetate content in 2 ml water was added and the mixture was stirred for 90 minutes. The solvents were removed and the resulting solid was triturated in deionized water as in Example 8 indicating less than 1% soluble peptide salt present The isolated solids were dried 4 days in vacuo to give 839 mg of white powder. The powder was ground and used for in vitro release assay (see Table VI, Example EXAMPLE 11 Formation of Peptide-polymer Ionic Conjugate Microparticle 1.50 of L-lactidelglycolide/d,l malic acid polyester (65: 33: 2).
Conjugates were synthesized by ring opening polymerization as in example 4 (MW 4700 polydispersity 1.3 as determined by GPC on a Jordi Gel 50 x 1 cm mixed linear bed column, THF eluent, Wyatt Mini Dawn light scattering detector dn/dc 0.05, add 1475 by titration, 42°C), was dissolved in 40 ml of acetone. The acid groups were neutralized with 2.0 mt of 0.SM sodium hydroxide solution and stirred for 5 minutes. A solution of 0.5 g of BIM-23014 (peptide content 83.7%, acetate content 11.5%) in 20 ml of Milli-Q water was slowly added with mixing to the polymer solution. An additional 40 ml of acetone was also added portionwise during the peptide addition to prevent precipitation. The clear, colorless solution was stirred for one hour and then evaporated to dryness under vacuum. The resulting white solid was redissolved in a mixture of 20 ml of acetone and 2 ml of Milli-Q water to form a clear solution. This solution was injected, via a 0.2 p teflon filter into a rapidly stirring reservoir of 500 ml Milli-Q water at 40C. The polymer/peptide complex phase s separated immediately into small particles upon contact with the water. After mixing the slurry for 30 min at 4 0 C, the residual acetone was removed under reduced pressure and the solids were isolated by centrifugation, resuspended with 100 ml of Milli-Q water, and recentrifuged. The isolated solids were dried by lyophilization to give 1530 mg of white free flowing powders. Particle size to range 2 100 gpm. The T, of the ionic conjugate was shown to occur at 53 0
C.
Total residual (unbound) peptide in all aqueous supematants was found to be 63 mg by HPLC analysis. The total initial peptide content was determined by elemental nitrogen analysis to be 19.9% by weight. The percentage of extractable peptide from the conjugate was determined to be 16.9%, by weight, is using the acetone/0.1M TFA extraction technique. The resulting conjugate, thus, retains 84.8% Ionic (extractable) character.
Rod Delivery System Type 1 (CONC2 and CGC1) Example A-1: Preparation of Citric Acid Initiated 9713 CaprolactonelGlycolide Copolymer (CGC1) A round bottom flask equipped for mechanical stirring was flame dried twice and purged with dry argon. The flask was charged with e-caprolactone (1.455 moles, 166g), glycolide (0.08865 moles, 10.3 g citric acid (0.075 moles, 14.4 and stannous octoate (0.0003 moles, 375 pl of 0.8 M solution in toluene). The polymerization was conducted using the following scheme: Under argon purge the charge was heated from room temperature to about 150 0 C over a period of about 1 hour and about 20 minutes with continuous stirring after melting (at 70 rpm). The charge was maintained at about 1500C for about 11.5 hours. At the conclusion of the polymerization, the small amount of unreacted monomer was distilled at about 1200C for about 15 minutes under vacuum (about 0.1 mm Hg). The material was poured into jars and allowed to cool.
The polymer was analyzed by GPC (Mn= 3543, Mw= 7708), FTIR, DSC (Tm 52.0°C), and titration for carboxylic content (average equivalent weight 623 Da).
Twenty grams of polymer were dissolved in 50.0 mL acetone, and s solution was precipitated in stirring ice-water. The solid product was isolated by filtration.
The purified polymer was analyzed by GPC (Mn= 4214, Mw= 9688), DSC (Tm 45.20C), and titration (average equivalent weight 780).
Example B-1: Preparation of Ionic Conjugate (CONC1) A 1.5 g purified polymer (CGC1) was dissolved in 7.5mL acetonitrile in a glass vial. In a separate vial 250.0 mg LHRH-acetate was dissolved in distilled water. The dissolved polymer was filtered through a 0.45 im Acrodisc syringe filter into a vial containing 83.8 mg sodium carbonate (to neutralize LHRH acetate). The LHRH solution was added dropwise to the filtered polymer is solution. The combined solution was mixed with a magnetic stir bar for about hours at room temperature. Conjugate was precipitated by adding it dropwise into stirring liquid-nitrogen cooled isopropyl alcohol (IPA). The precipitate was collected by centrifugation and dried over night under vacuum.
The conjugate yield was 73.5%. Conjugate was analyzed by DSC (Tm 50.90C) and FTIR. Elemental analysis of the material yielded 1.81% nitrogen. Based upon this, the LHRH content was determined to be 10.0%.
Example C-1: Preparation of a Rod Form Delivery System Ionic conjugate (0.3987g of CONC2) and polymer (1.206g of CGC1) were mixed by gentle grinding and melted together at about 58°C in a heating block. The melted material was mixed and then drawn into 18G capillary tubes and allowed to cool. It was extruded and the rods cut into lengths that had the proper dosage of drug and placed into a sterile 10-gauge spiral needle (ready for injection). All steps of Example C-1 were conducted in a laminar flow hood.
The rods had a LHRH content of Rod Delivery System Type 2 (CONC2 and CGC1) Example A-2: Preparation of Citric Acid Initiated 97/3 CaprolactonelGlycolide Copolymer (CGC1) The same polymer (CGC1) made in Example A-1 was used in this s example.
Example B-2: Preparation of Ionic Conjugates (CONC2) CONC2 was prepared according to the procedure described in Example B-1. By elemental analysis, the percent nitrogen was 2.31%. Based on this the LHRH content was 12.76%.
io Example C-2: Preparation of a Rod Form Delivery System CONC2 (0.1854 g) and 0.5565 g of purified CGC1 were mixed mechanically and then heated to about 60 0 C. Mixed and melted material was drawn up into 18-gauge capillary tubes and extruded with a plunger. The rods were cut into lengths that had the proper dosage of drug and placed into a sterile 18-gauge spinal needle (ready for injection). All steps of Example C-2 were conducted in a laminar flow hood. The rods had a LHRH content of 3.2%.
Rod Delivery System Type 3 Example A-3: Preparation of Tartaric Acid Initiated 9812 Caprolactone/Trimethylene carbonate (TMC) Copolymer (CTT1) A round bottom flask equipped for mechanical stirring was flame dried three times and purged with dry argon. The flask was charged with ecaprolactone (1.47 moles, 168g), TMC (0.03 moles, 3.06 g tartaric acid (0.0142 moles, 2.134 and stannous octoate (0.0003 moles, 375 l of 0.8 M solution in toluene). The polymerization was conducted using the following scheme: Under argon purge the charge was heated from room temperature to about 150 0 C over a period of about 1 hour while stirring the molten reaction mixture (60 rpm). The temperature was maintained at about 150 0 C for about 9 hours. Unreacted monomer was distilled at about 100 0 C for about 1 hour under reduced pressure (0.1 mm). The polymer was poured into jars and allowed to cool.
Polymer was analyzed by GPC (Mn= 13221, Mw 35602).
Example B-3: Preparation of Ionic Conjugates (CONCTT1) A 1.5 g purified polymer from Example A-3 was dissolved in acetonitrile in a glass vial. In a separate vial, 250 mg LHRH-acetate was dissolved in 1.5m] distilled water. The dissolved polymer was filtered through a 0.45 pm Acrodisc syringe filter into a vial containing 56.5 mg sodium carbonate (to neutralize LHRH-acetate). The LHRH solution was added dropwise to the filtered polymer solution. The combined solution was mixed with a magnetic stir bar for about 3 hours at room temperature. Conjugate was precipitated by adding it dropwise into stirring liquid nitrogen cooled IPA. The precipitate was io collected by centrifugation and dried over night under vacuum.
The conjugate yield was 81.1%. Elemental analysis of the material yielded 2.04% nitrogen. Based upon this, the LHRH content was determined to be 11.3%.
Example C-3: Preparation of a Rod Form Delivery System is CTT1 (0.8909 g) was melted at about 55C. To this was added 0.2250 g of CONCTT1 and the entire system was heated to about 650C. The molten system was then drawn up into 18 gauge capillary tubes and extruded with a plunger. The rods were cut into lengths that had the proper dosage of drug and placed into a sterile 18 gauge spiral needle (ready for injections). All steps of example C-3 were conducted in a laminar flow hood. The rods had an LHRH content of 2.3%.
Rod Delivery System Type 4 Example A-4: Preparation of Tartaric Acid Initiated 94/6 CaprolactonelGlycolide Copolymer (CGT6) A round bottom flask equipped for mechanical stirring was flame dried three times and purged with dry argon. The flask was charged with ecaprolactone (1.41 moles, 161g), glycolide (0.09 moles, 10.4 g tartaric acid (0.005 moles, 0.73 and stannous octoate (0.0003 moles, 375 pl of 0.8 M solution in toluene). The polymerization was conducted using the following o3 scheme: Under argon purge the charge was heated from room temperature to about 150 0 C over a period of about 1 hour while stirring the molten reaction mixture (60 rpm). The temperature was maintained at about 150 0 C for about 1 hour. It was then raised to about 180°C for about four hours. Material was cooled to about 107°C and placed under vacuum at 1.5mm Hg for about hours. The material was poured into jars and allowed to cool.
After collection, the polymer was analyzed by DSC (Tm 54.5C) and GPC (Mn 26254 Mw 68101).
Example B-4: Preparation of Ionic Conjugates (CONCTT2) CONCTT2 was prepared as described in Example B-1 but using LHRHacetate and the copqlymer of Example A4.
Example C-4: Preparation of a Rod Form Delivery System CGT6 (1.4g) and CONCTT2 (0.4779g) were heated to about 57°C, cooled, chopped, then reheated to the same temperature. The molten system was then drawn up into 18 gauge capillary tubes and extruded with a plunger.
The rods were cut into lengths that had the proper dosage of drug and placed into a sterile 18 gauge spiral needle (ready for injections). All steps of Example is C-4 were conducted in a laminar flow hood. The rods had an LHRH content of 2.8%.
Example D-4: Coating of System C-4 Rod Using Inert Copolymer Precursor CGT6 (1.4 g) was dissolved in 1.5 ml dichloromethane. The rods from Example C-4 were dipped into this polymer solution, immediately removed, and dried under ambient conditions in a laminar flow hood.
From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention, and without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions. Thus, other embodiments are also within the claims.
Throughout this specification and the claims, the words "comprise", "comprises" and "comprising" are used in a non-exclusive sense, except where the context requires otherwise.
variations and modifications of this device will be apparent to the person skilled in the art, and those variations and modifications are within the scope of the present invention.
It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents forms part of the common general knowledge in the art, in Australia or in any other country.