Abstract:
A compatible, biodegradable microcapsule delivery system for active ingredients, including hormonally active peptides, proteins, or other bioactive molecules, and a method of making the same. The ingredients are encapsulated in biodegradable copolymer excipients of varying mole ratios and the blend of the microcapsules are administered to an animal. Delivery of the ingredient occurs over a prolonged period of time at a constant rate as a result of the varying break-down rates of the copolymer excipients.

Description:
BACKGROUND OF THE INVENTION 
     It is known that a marked inhibition of pituitary and gonadal function that occurs after chronic administration of the [D-Trp 6 , des-Gly 10  ]-LHRH ethylamide an analog of luteinizing hormone releasing hormone (LHRH) and other LHRH analogs leads to a reduction in steroidal sex hormones and makes possible approaches for the use as a contraceptive or for the treatment of sex hormone-dependent tumors. Concerning the latter, studies involving rats treated with LHRH analogs show the potential clinical efficacy of the hormone in the treatment of prostate carcinoma and other hormone-dependent tumors in animals. 
     The treatment of hormone-dependent tumors and other disorders in animals would be greatly enhanced by a delivery system which, after a single administration, maintained controlled levels of active ingredients, including [D-Trp 6 , des-Gly 10  ]-LHRH ethylamide and its related analogs, over extended periods of time. Traditional methods of administering peptides (or proteins) result in high initial concentrations of peptide (or protein) analog in the tissue, but over a short period of time, i.e., over a few minutes to several hours, peptide levels in the blood decline. Therefore, optimal pharmacological effects are most often not achieved. The result is a need for more frequent administration of higher-dosage regimens. 
     More recently, a polymer of poly(D,L-lactide-co-glycolide) (DL-PLG), which is biodegradable and biocompatible with living tissue, has been used in microcapsules for longer acting delivery systems. Systems of microencapsulated active ingredients in polymers and copolymers of lactic acid and glycolic acid have been used to achieve controlled release of chemical and biological pharmaceuticals. For example, U. S. Pat. No. 3,773,919 discloses a drug, stated to include water-soluble antibiotic peptides encapsulated in lactide/glycolide copolymers so as to provide controlled release. Canadian Patent No. 1,176,565 discloses a microcapsule composition comprising a core containing a LHRH peptide encapsulated in a biodegradable, biocompatible copolymer excipient. 
     Microencapsulation for controlled release of enzymes, hormones and other biologicals are discussed in papers by Sanders, Kent, McRae, Vickery, Tice, and Lewis, Journal of Pharmaceutical Sciences, Vol. 73, pp. 1294-1296, September 1984 and by Redding, Schally, Tice and Meyers, Proc. Natl. Acad. Sci. USA, Vol. 81, pp. 5845-5848, September 1984. The first paper describes a system controlled by diffusion and erosion, wherein the kinetics of compound release determined by the parameters of the copolymer, and more particularly, the controlled release of nafarelin acetate, an analog of LHRH, from poly(D,L-lactide-co-glycolide) microspheres. The second paper discloses the inhibition of rat prostate tumors by controlled release of [D-Trp 6  ] luteinizing hormone-releasing hormone from injectable microcapsules. 
     The microcapsule systems described in the above-publications all share a common feature in that the release of the compound is controlled by the porosity and/or erosion of a polymer continuum. Also, all the described microcapsule systems utilize only a single type of copolymer. Therefore, while a controlled release of the compound is achieved, such is limited by the specific lactide/glycolide ratio used in the encapsulating material. At the most, the methods previously used, and particularly the peptide microcapsules, provided release times of approximately one month. 
     There exists, therefore, a need for a method of delivering active ingredients, including peptides, proteins and other bioactive molecules used in treating disease, which utilize the advantages of microencapsulation, but which provides a longer controlled duration of release than that presently known. Also, there exists a need for a method of providing a constant dose regimen of active ingredient throughout the longer release time provided by using biodegradable microcapsules. 
     SUMMARY OF THE INVENTION 
     This invention relates to a method of delivering an active ingredient into the system of an animal at a constant rate over a long period of time, i.e., one and one-half to six months or longer. A composition comprising a blend of free flowing spherical particles is obtained by individually microencapsulating quantities of the ingredient in different copolymer excipients which biodegrade at varying rates. An effective amount of the microcapsule blend may be administered to the animal parenterally (e.g., intravenously, intramuscularly, subcutaneously, intranasally, intraperitoneally, or by inhalation). 
     A quantity of these particles are of such a copolymer excipient that the core active ingredient is released quickly after injection, and thereby delivers the ingredient for an initial period. A second quantity of the particles are of such type excipient that delivery of the encapsulated ingredient begins as the first quantity&#39;s delivery begins to decline. A third quantity of ingredient may be encapsulated with a still different excipient which results in delivery beginning as the delivery of the second quantity beings to decline. Obviously, still greater assortments of excipients can be used to obtain more prolonged release time of the encapsulated ingredient. A further modification of the present invention could be to have different ingredients encapsulated within a blend of varying excipient formulations. 
     It is shown, therefore, that as the usefulness of one type of particle begins to decline or run out, another type begins to take over. This provides a preselected, constant rate of delivery over a prolonged period of time. For example, by varying the lactide/glycolide ratio in a poly(D,L-lactide-co-glycolide) encapsulation, as well as the types and quantities of encapsulated active ingredient, it is possible to design a long-term, controlled-release profile of choice. 
     More particularly, the invention relates to a compatible, biodegradable, injectable microcapsule delivery system for the peptide agonist [D-Trp 6  , des-Gly 10  ]-LHRH ethylamide (hereinafter referred to as the &#34;agonist&#34;) and for the peptide antagonist [D-N-Ac-4-Cl-Phe 2 , D-trp 6 , D-Ala 10  ]-LHRH (or an LHRH antagonist of similar structure) (hereinafter referred to as the &#34;antagonist&#34;). The microcapsule formation consists of free-flowing spherical particles, preferably of poly(D,L-lactide-co-glycolide) which can be administered parenterally, (e.g. intravenously, intramuscularly, subcutaneously, intranasally, intraperitoneally or by inhalation). By utilizing a combination of various polymers with different lactide/glycolide ratios, one can greatly prolong the release profile of the encapsulated LHRH analog. Delivery periods of six months or more can be achieved. 
     It is an object of this invention to provide a biocompatible, biodegradable microcapsule delivery system for an active ingredient which will deliver the ingredient at a constant rate over a long period of time. 
     It is a still further objective of this invention to provide a formulation comprising a core of active ingredient and various encapsulating copolymer excipients which is biocompatible and biodegradable and which can be utilized in a microcapsule delivery system. 
     It is another object of the invention to provide a biocompatible microcapsule delivery system for the agonist [D-Trp 6 , des-Gly 10  ]-LHRH ethylamide which delivers the agonist at a constant rate of approximately 50 μg to 250 μg or more per day for a duration of from one and one-half to six months or more in men and women. 
     It is another object of this invention to provide a biocompatible, biodegradable microcapsule delivery system for the antagonist [D-N-Ac-4-Cl-Phe 2 , D-Trp 6 , D-Ala 10  ]-LHRH, or an LHRH antagonist of similar structure, which delivers that antagonist at a constant rate of about 200 μg to 500 μg or more per day for a duration of from one to three months or more. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The microcapsule delivery system of this invention is designed to deliver an ingredient at a constant rate over time. FIG. 1 shows the presence of LHRH in the blood over time. The LHRH was delivered by this invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     An illustration of the method of performing one embodiment of the invention, that is, the use of LHRH agonist encapsulated in poly(D,L-lactide-co-glycolide), follows. In addition, the details and results of a study utilizing this embodiment in rats are provided. 
     It should be noted, however, that other polymers besides poly(D,L-lactide-co-glycolide) may be used. Examples of such polymers include, but are not limited to: polyacetal polymers, polyorthoesters, polyesteramides, polycaprolactone and copolymers thereof, polycarbonates, polyhydroxybuterate and copolymers thereof, polymaleamides, copolyaxalates and polysaccharides. 
     I. PREPARATION OF DL-PLG EXCIPIENTS 
     The general procedures used to prepare DL-PLG copolymers and the results of their characterization are detailed in the following sections. 
     a. DL-Lactide Purification 
     DL-lactide was used to prepare the polymers. To purify the monomer, it is first dissolved by heating a mixture of the monomer in a volume of dry (stored over molecular sieves) ethyl acetate about equal to its weight. While still hot, the solution is vacuum filtered through an extra coarse, fitted-glass gas-dispersion tube. The solvent level is reduced with an aspirator to a level equal to about half the weight of the lactide. The solution is then allowed to cool slowly to room temperature and chilled in an ice-water bath to effect crystallization. The monomer is finally filtered in a nitrogen-filled glove box. The monomer is recrystallized from ethyl acetate two additional times in this manner. All glassware used after the initial hot filtration and recrystallization is oven dried overnight at 150° C. prior to use. After the final recrystallization, the purified monomer is vacuum dried in a desiccator and stored in oven-dried glass jars until ready for use. 
     b. Glycolide Synthesis and Purification 
     The glycolide monomer is prepared and purified by the following method: Excess water is first distilled from 67% aqueous glycolic acid (Eastman Chemicals, Rochester, N.Y.) in a 3-neck flask equipped with a thermometer, distillation head, and a condenser. The solution is boiled at reduced pressure with the use of a water aspirator. After the excess water has evolved, heating is continued to remove additional water by dehydration of the glycolic acid. After no further water is evolved, the flask is allowed to cool to room temperature under vacuum. At this point, about 1 percent by weight of antimony oxide, based on the theoretical glycolic acid content, is added to the flask as a catalyst. The distillation head and condenser are removed, and the flask is connected to two receiving flasks and a trap arranged in series. The receiving flasks and trap are cooled by dry-ice:isopropanol baths. (Note: The first receiving flask is for product collection. The second receiving flask is actually a trap). The pressure is reduced to about 2 mmHg, and the reaction flask is heated to distill the crude glycolide. The material that distills between 110°  and 130° C. is collected in the first receiving flask. 
     The crude glycolide collected is next purified by first washing the product. This is achieved by slurrying the glycolide in isopropanol, followed by filtering and vacuum drying, and then by three recrystallizations from ethyl acetate. After washing, precautions are made to protect the glycolide from atmospheric moisture during each stage of recrystallization by using oven-dried glassware, dry ethyl acetate (stored over molecular sieves), and a glove box filled with nitrogen. The crude glycolide is combined with a volume of ethyl acetate approximately equal to three-fourths its weight. The mixture is then heated to reflux to dissolve the glycolide and cooled slowly to room temperature to allow crystallization. The monomer is recrystallized three times in this manner. After each recrystallization, the glycolide crystals are collected by vacuum filtration in a glove box. After the final recrystallization, the product is dried at room temperature under a vacuum of &lt;2 mmHg in a desiccator. The purified dried monomer is then stored in oven-dried glass jars placed inside a desiccator. 
     c. Copolymer Synthesis 
     All glassware is oven dried at 150° C. overnight and allowed to cool in a nitrogen-filled glove box. All handling of the reactants and assembling of apparatus is done in the glove box. The purified monomers are weighed directly into a 3-neck, round-bottom flask. After being charged and sealed, the flask assembly is evacuated three times, back filled with nitrogen, removed from the glove box, connected to a dry nitrogen purge, and placed into an oil bath maintained at 170° C. Once the monomers have partially melted, stirring is begun. Positive nitrogen pressure is maintained over the monomers throughout the polymerization. After the monomers have completely melted, 0.05 percent by weight of stannous octoate is introduced into the flask with a microsyringe. Stirring is continued until the mixture becomes too viscous to stir, at which point the stirrer is raised out of the melt. The polymerization is then continued for a total reaction time to 16 to 18 h. Next, the resulting polymer is allowed to cool to room temperature under a nitrogen atmosphere and removed by breaking the flask. Any residual glass is removed from the polymer plug by submerging it into liquid nitrogen. While cold, the polymer is broken into several smaller pieces and dissolved in methylene chloride and precipitated into methanol. The solvent is then removed by evaporation at room temperature under a hood and, finally, under vacuum at &lt;2 mmHg and about 40° C. The yields are typically about 75% of theoretical. The polymers are then characterized and stored in a desiccator until ready for use. 
     II. PREPARATION AND CHARACTERIZATION OF AGONIST LHRH MICROCAPSULES 
     The phase-separation microencapsulation process is used in this example to prepare microcapsules with the LHRH agonist and DL-PLG excipients. DL-PLG is dissolved in methylene chloride and placed in a resin kettle equipped with a true-bore stirrer that is fitted with a 1.5-in. Teflon turbine impeller and powered by a Fisher Stedi-speed stirrer at a speed of about 3000 rpm. The peptide is then dispersed in the stirred copolymer solution followed by the addition of silicone oil (Dow 200 Fluid, 350 cSt, Dow Corning Corp., Midland, Mich.) to the resin kettle. This silicone oil causes the DL-PLG to coacervate and deposit onto the peptide particles. Immediately after the silicone addition is complete, the contents of the resin kettle are poured into 2 L of heptane being stirred at about 800 rpm with a 2-in. stainless steel impeller. The heptane causes the microcapsules to harden by extracting methylene chloride out of the microcapsules. After the stirring is continued for 30 min., the hard microcapsules are isolated by filtration and dried for 24 hours in a vacuum desiccator maintained at room temperature. 
     The core loading of the microcapsules is a measure of the amount of LHRH incorporated inside the microcapsules. This analysis is based on the extraction of core material (LHRH) from a known amount of microcapsules and quantification of the extracted LHRH by high performance liquid chromatography. A known amount of microcapsules is dissolved in methylene chloride. The LHRH is then extracted into triethylammonium phosphate (TEAP) buffer (pH 2.5) and is injected into an HPLC for quantification. 
     The theoretical core loading for a batch of microcapsules is based upon the copolymer and LHRH input and is calculated in the following manner: ##EQU1## 
     The actual core loading is determined by assaying the microcapsules by the procedure described above. The actual core loading is calculated in the following manner: ##EQU2## 
     The encapsulation efficiency is the ratio of the actual and theoretical core loadings and is calculated in the following manner: ##EQU3## 
     III. PHARMACOKINETICS STUDIES OF AGONIST MICROCAPSULES IN RATS 
     Pharmacokinetics studies were performed involving the microencapsulation of agonist LHRH in DL-PLGs with varying lactide/glycolide ratios. A formulation of a blend of agonist microcapsules prepared with mole ratios of 52:48, 68:32, and 85:15  DL-PLG excipients were used. This blend consisted of appropriate amounts of 3%-loaded agonist microcapsules prepared with 52:48 DL-PLG, 10%-loaded against microcapsules prepared with 68:32 DL-PLG, and 8% loaded agonist microcapsules prepared with 85:15 DL-PLG excipients. The 52:48 DL-PLG component of the blend was designed to deliver agonist during the first month after administration of the microcapsules. The 68:32 DL-PLG component was designed to release the agonist primarily during the second month after administration, and the 85:15 component was designed to release the agonist primarily during the third through sixth months. Overall, the blend was designed to release approximately 50 μg of agonist per day for 180 days. 
     Studies with the agonist microcapsules were initiated. A total of 80 male rats were used in the studies. Three groups of 20 rats each were administered three agonist microcapsule formulations, and one group of 20 rats (a control group) was administered placebo microcapsules (empty microcapsules). Blood was collected for six months from the animals receiving the prototype six month formulation, the 85:15 formulation, and the placebo microcapsules. Blood was collected for four months from animals treated with the agonist microcapsule formulation prepared with 68:32 DL-PLG. Ten rats from each group were bled on Fridays. Agonist serum levels were determined for all 80 rats during month 1. Thereafter, agonist serum levels were determined only for rats bled on Fridays. 
     CONCLUSION 
     The levels of agonist serum were determined using radioimmunoassay (RIA). RIA results from serum samples collected during the test period showed that a constant release of agonist LHRH was released over the six months. Correspondingly, the concentration of testosterone in serum was found to be suppressed to castrate levels during the controlled release of the LHRH from the single injection of similar microcapsules. After approximately six months, when the microcapsules were depleted of their LHRH, the testosterone levels returned to normal. 
     Table 1 and FIG. 1 show the agonist serum levels obtained with the prototype six-month agonist microcapsule formulation. 
     Table 2 shows the agonist serum levels obtained with agonist microcapsules prepared with 85:15 DL-PLG. 
     Table 3 shows the agonist serum levels obtained with agonist microcapsules prepared with 68:32 DL-PLG. 
     Table 4 shows the results of the control group study using placebo microcapsules. 
     
                                           TABLE 1__________________________________________________________________________AGONIST SERUM LEVELS OBTAINED WITH PROTOTYPE SIX-MONTH AGONISTMICROCAPSULE FORMULATION: COMPOSITE D196-150SSerum                                                 Average LHRNcollection    LHRN in serum, pg/mL.sup.a              in serum,Group    date  Day Rat 1             Rat 2                 Rat 3                     Rat 4                         Rat 5                             Rat 6                                 Rat 7                                     Rat 8                                         Rat 9                                             Rat 10                                                 pg/mL__________________________________________________________________________                                                 ± SEA   6-24-85     0   99  118 99  99  99  99  99  99  99  99  101  3.4B   6-24-85     0   99  100 99  100 99  100 100 100 99  99  100  0.5A   7-02-85     8   1513             2555                 1604                     972 1127                             1240                                 617 995 746 2050                                                 1342 470.9B   7-05-85     11  2133             2141                 2423                     1813                         5416                             3174                                 3569                                     3673                                         3602                                             3791                                                 3174 836.8A   7-09-85     15  1543             1549                 1495                     1777                         1751                             1310                                 823 1624                                         893 2013                                                 1478 281.5B   7-12-85     18  548 839 985 706 516 989 655 761 790 687 748  125.2A   7-16-85     22  2016             1007                 1503                     2334                         1880                             1033                                 1101                                     1492                                         1085                                             2130                                                 1558 425.5B   7-19-85     25  750 653 774 721 796 1112                                 638 703 804 988 794  104.9A   7-23-85     29  1658             2181                 1723                     1257                         2657                             1481                                 1937                                     2269                                         1866                                             1432                                                 1846 335.9B   7-26-85     32  3322             3701                 5424                     3871                         4996                             4254                                 4008                                     4885                                         3643                                             4493                                                 4260 551.8A   7-30-85     36  3893             5228                 3050                     2805                         3909                             2088                                 2356                                     5228                                         3898                                             1546                                                 3400 1031.1B   8-02-85     39  1961             1727                 1637                     2415                         1710                             1899                                 1750                                     2683                                         1902                                             2340                                                 2002 286.2B   8-09-85     46  5444             2921                 4212                     4534                         3838                             5008                                 2859                                     3827                                         2455                                             3044                                                 3814 795.6B   8-16-85     53  3340             1454                 2104                     2264                         1433                             3077                                 2486                                     4589                                         1834                                             2464                                                 2505 698.5B   8-23-85     60  2083             2847                 2150                     2181                         2639                             3243                                 2777                                     4544                                         2135                                             1631                                                 2623 587.0B   8-30-85     67  3319             1975                 2023                     1883                         2384                             2741                                 3680                                     2124                                         3889                                             1851                                                 2587 656.3B   9-06-85     74  5017             2471                 3628                     4588                         2318                             4639                                 4207                                     3940                                         4563                                             3223                                                 3859 759.5B   9-13-85     81  5206             5084                 5114                     5857                         3154                             7253                                 6765                                     5303                                         7314                                             6163                                                 5721 949.1B   9-20-85     88  4356             6119                 4397                     5007                         2793                             3831                                 2482                                     2485                                         4796                                             2552                                                 3882 1053.2B   9-27-85     95  4997             1856                 2425                     2022                         1220                             5916                                 2742                                     3095                                         2271                                             1227                                                 2777 1135.3B   10-04-85     102 2055             1407                 1907                     1864                         1234                             3311                                 2083                                     2805                                         2284                                             1844                                                 2079 433.1B   10-11-85     109 4381             4034                 3959                     4257                         2227                             3597                                 3960                                     4381                                         4381                                             3697                                                 3887 428.2B   10-18-85     116 3182             1206                 1697                     1409                         823 ND.sup.b                                 2349                                     1648                                         3283                                             2382                                                 1998 700.3B   10-25-85     123 3878             1962                 3592                     1592                         1402                             ND  2340                                     2344                                         3402                                             4060                                                 2730 871.7B   11-01-85     130 2851             1399                 2026                     1368                         982 ND  1275                                     2204                                         3662                                             1819                                                 1954 654.7B   11-08-85     137 1230             1194                 2320                     1326                         1222                             ND  1602                                     2015                                         1712                                             1041                                                 1518 346.7B   11-15-85     144 1463             933 1966                     1184                         1416                             ND  1440                                     1889                                         1503                                             1394                                                 1465 206.4B   11-22-85     151 910 872 2343                     1270                         1560                             ND  1355                                     2497                                         1571                                             1058                                                 1493 441.3B   11-29-85     158 554 906 1447                     1015                         1626                             ND  1040                                     2623                                         1465                                             842 1280 463.5B   12-06-85     164 295 350 677 510 411 ND  427 834 636 384 503  145.7B   12-13-85     171 259 378 492 519 391 ND  569 882 459 343 477  127.1B   12-20-85     178 275 533 755 442 392 ND  437 532 511 269 461  106.1B   12-27-85     185 227 349 599 640 590 ND  355 610 518 324 468  134.6B   1-03-86     192 155 382 654 513 548 ND  466 783 515 360 486  128.2__________________________________________________________________________ .sup.a Serum samples were analyzed at Research Triangle Institute using radioimmunoassay. .sup.b ND = Not determined. 
    
     
                                           TABLE 2__________________________________________________________________________AGONIST SERUM LEVELS OBTAINED WITH AGONIST MICROCAPSULESPREPARED WITH 85:15 DL-PLG: COMPOSITE D196-060-1SSerum                                                 Average LHRNcollection    LHRN in serum, pg/mL.sup.a              in serum,Group    date  Day Rat 1             Rat 2                 Rat 3                     Rat 4                         Rat 5                             Rat 6                                 Rat 7                                     Rat 8                                         Rat 9                                             Rat 10                                                 pg/mL__________________________________________________________________________                                                 ± SEC   6-24-85     0   100 100 99  100 100 99  100 99  99  100 100  0.5D   6-24-85     0   100 99  913 100 130 100 99  124 115 99  188  145.0C   7-02-85     8   491 1075                 950 509 1097                             1278                                 1259                                     1077                                         1061                                             1652                                                 1045 237.1D   7-05-85     11  2806             2613                 2921                     1465                         1973                             2390                                 2352                                     3434                                         3357                                             1489                                                 2480 546.2C   7-09-85     15  642 783 778 1961                         973 966 610 1215                                         730 704 936  274.0D   7-12-85     18  488 426 248 582 384 314 453 402 506 425 423  68.6C   7-16-85     22  1417             460 609 1451                         354 521 800 1118                                         543 539 781  332.2D   7-19-85     25  441 346 315 491 770 191 480 508 471 477 449  100.6C   7-23-85     29  932 449 432 581 274 357 414 345 262 256 430  134.6D   7-26-85     32  384 467 964 1098                         510 360 842 773 1202                                             573 717  258.5C   7-30-85     36  1291             772 513 426 351 553 461 312 398 356 543  197.2D   8-02-85     39  343 227 298 417 265 252 347 293 342 296 308  43.4D   8-09-85     46  979 908 568 1119                         825 262 1366                                     895 1586                                             1053                                                 956  264.5D   8-16-85     53  1679             1301                 1817                     1368                         617 941 1332                                     1492                                         1697                                             1831                                                 1408 295.7D   8-23-85     60  2197             1981                 1173                     525 1945                             1590                                 1993                                     2513                                         3116                                             1650                                                 1868 507.0D   8-30-85     67  2232             2449                 2004                     1319                         1132                             2196                                 1760                                     3635                                         2088                                             2029                                                 2084 435.6D   9-06-85     74  5206             4433                 2616                     2882                         1381                             4311                                 3492                                     3676                                         2115                                             1953                                                 3207 1017.1D   9-13-85     81  4187             3238                 3742                     3627                         3559                             6394                                 2302                                     3977                                         3383                                             3500                                                 3791 637.1D   9-20-85     88  2365             3549                 2272                     2310                         5396                             5202                                 2834                                     1874                                         4697                                             2708                                                 3321 1112.2D   9-27-85     95  3494             2938                 1466                     1812                         1439                             1411                                 1662                                     1142                                         2149                                             1414                                                 1893 580.6D   10-04-85     102 2911             4381                 3878                     2230                         2094                             1938                                 3168                                     1677                                         3461                                             1841                                                 2758 801.9D   10-11-85     109 3639             4381                 4286                     4381                         4381                             2745                                 4381                                     4381                                         4381                                             3222                                                 4018 489.5D   10-18-85     116 1323             2065                 1684                     1235                         1080                             886 1296                                     1747                                         1309                                             1080                                                 1371 276.9D   10-25-85     123 3781             2712                 2323                     1875                         2400                             1625                                 7735                                     2672                                         1408                                             3132                                                 2966 1149.8D   11-01-85     130 1620             1937                 1819                     1720                         1577                             1078                                 4031                                     3498                                         1559                                             2285                                                 2112 695.4D   11-08-85     137 1588             1244                 1695                     2511                         1168                             1199                                 3514                                     3094                                         1893                                             1340                                                 1925 669.0D   11-15-85     144 1736             1450                 1874                     1080                         1297                             804 5439                                     2497                                         1756                                             2111                                                 2004 806.8D   11-22-85     151 2638             1279                 1760                     1720                         1319                             1124                                 3521                                     2566                                         1418                                             1502                                                 1885 614.2D   11-29-85     158 1645             1301                 1777                     1119                         1048                             670 4319                                     1800                                         1174                                             1396                                                 1625 608.3D   12-06-85     164 748 680 780 533 724 396 970 580 784 525 672  130.8D   12-13-85     171 715 ND.sup.b                 816 740 699 349 1227                                     925 757 708 771  136.3D   12-20-85     178 605 ND  555 395 488 241 807 604 514 584 533  105.4D   12-27-85     185 572 ND  594 364 422 260 832 543 605 513 523  115.9D   1-03-86     192 521 ND  666 514 660 314 1029                                     636 811 492 627  140.7__________________________________________________________________________ .sup.a Serum samples were analyzed at Research Triangle Institute using radioimmunoassay. .sup.b ND = Not determined. 
    
     
                                           TABLE 3__________________________________________________________________________AGONIST SERUM LEVELS OBTAINED WITH AGONIST MICROCAPSULESPREPARED WITH 68:32 DL-PLG: COMPOSITE D196-059-1SSerum                                                 Average LHRNcollection    LHRN in serum, pg/mL.sup.a              in serum,Group    date  Day Rat 1             Rat 2                 Rat 3                     Rat 4                         Rat 5                             Rat 6                                 Rat 7                                     Rat 8                                         Rat 9                                             Rat 10                                                 pg/mL__________________________________________________________________________                                                 ± SEE   6-24-85     0   99  632 100 100 100 126 102 100 100 99  156  95.2F   6-24-85     0   100 99  99  99  158 100 100 100 89  100 104  10.7E   7-02-85     8   336 242 307 340 343 152 195 242 286 272 272  51.0F   7-05-85     11  435 287 519 390 285 480 370 423 389 ND  398  59.3E   7-09-85     15  578 262 182 287 356 522 276 183 565 333 354  120.7F   7-12-85     18  380 206 201 230 224 268 ND.sup.b                                     197 248 ND  244  40.8E   7-16-85     22  665 661 554 557 514 559 1100                                     307 976 521 641  167.3F   7-19-85     25  147 217 257 172 175 218 ND  310 252 ND  219  40.9E   7-23-85     29  1134             1200                 483 719 865 992 855 544 2267                                             425 948  359.9F   7-26-85     32  3798             910 1497                     1542                         1000                             2060                                 ND  1313                                         835 ND  1619 654.8E   7-30-85     36  1933             1079                 1592                     570 1815                             1091                                 593 1582                                         1966                                             807 1303 474.8F   8-02-85     39  2050             664 619 1080                         396 457 ND  416 656 ND  792  467.6F   8-09-85     46  1385             975 1221                     1786                         416 1478                                 ND  704 807 ND  1097 516.1F   8-16-85     53  845 758 684 1031                         501 859 ND  693 1073                                             ND  806  278.3F   8-23-85     60  711 456 260 389 357 557 ND  324 731 ND  473  210.6F   8-30-85     67  223 351 332 347 194 353 ND  264 524 ND  324  122.6F   9-06-85     74  380 272 276 299 222 360 ND  287 312 ND  301  90.0F   9-13-85     81  266 229 194 201 242 241 ND  188 223 ND  223  61.8F   9-20-85     88  186 156 139 163 160 176 ND  163 253 ND  175  53.2F   9-27-85     95  204 247 160 161 142 161 ND  136 176 ND  173  56.0F   10-04-85     102 115 82  81  141 102 107 ND  77  100 ND  101  32.8F   10-11-85     109 135 88  62  62  79  62  ND  62  64  ND  77   29.8__________________________________________________________________________ .sup.a Serum samples were analyzed at Research Triangle Institute using radioimmunoassay. .sup.b ND = Not determined. 
    
     
                                           TABLE 4__________________________________________________________________________CONTROL GROUPS FOR PHARMACOKINETICS STUDIES, PLACEBO MICROCAPSULESPREPARED WITH 85:15 DL-PLG: COMPOSITE D196-105-1SSerum                                                 Average LHRNcollection    LHRN in serum, pg/mL.sup.a              in serum,Group    date  Day Rat 1             Rat 2                 Rat 3                     Rat 4                         Rat 5                             Rat 6                                 Rat 7                                     Rat 8                                         Rat 9                                             Rat 10                                                 pg/mL__________________________________________________________________________                                                 ± SEG   6-24-85     0   100 100 116 137 596 120 99  145 99  104 162  81.3H   6-24-85     0   100 100 99  99  100 100 100 100 99  100 100  0.5G   7-02-85     9   100 100 100 100 100 100 100 100 100 100 100  0.1H   7-05-85     11  82  82  82  82  82  82  82  82  82  82  82   0.1G   7-09-85     15  100 100 100 100 100 100 100 100 100 100 100  0.1H   7-12-85     18  83  82  82  91  94  82  82  88  82  82  85   3.6G   7-16-85     22  96  96  96  96  96  96  96  96  96  96  96   0.1H   7-19-85     25  96  96  96  96  96  96  96  96  96  96  96   0.1G   7-23-85     29  96  96  96  96  96  96  96  96  96  96  96   0.1H   7-26-85     32  99  99  99  99  99  99  99  99  99  99  99   0.1G   7-30-85     36  99  99  99  99  99  99  99  99  99  99  99   0.1H   8-02-85     39  70  73  91  146 73  62  57  75  71  63  78   14.7H   8-09-85     46  68  74  80  150 87  63  57  58  71  69  78   16.0H   8-16-85     53  108 24  24  48  24  24  24  41  24  24  37   16.3H   8-23-85     60  39  43  54  104 49  39  38  54  66  37  52   12.3H   8-30-85     67  64  43  63  160 84  72  53  53  76  64  73   19.2H   9-06-85     74  66  86  71  126 78  77  56  78  90  74  80   11.7H   9-13-85     81  108 93  121 129 105 163 81  112 116 93  112  14.3H   9-20-85     88  70  73  77  132 94  88  70  65  85  97  85   13.0H   9-27-85     95  98  97  94  85  85  82  105 95  104 79  92   6.5H   10-04-85     102 63  62  77  85  65  70  62  62  66  73  69   6.2H   10-11-85     109 64  62  62  62  62  62  62  62  65  62  63   0.8H   10-18-85     116 62  62  62  68  62  62  55  55  57  64  61   3.1H   10-25-85     123 58  62  56  85  67  57  55  61  55  67  62   6.4H   11-01-85     130 85  56  73  97  72  80  71  65  87  70  77   9.1H   11-08-85     137 74  63  87  75  83  71  55  66  73  60  71   7.8H   11-15-85     144 89  89  89  89  89  89  89  89  89  89  89   0.0H   11-22-85     151 92  89  89  89  89  89  89  89  96  89  90   1.6H   11-29-85     158 89  89  89  89  89  89  89  89  89  89  89   0.0H   12-06-85     164 89  89  89  93  89  89  89  89  89  89  89   0.7H   12-13-85     171 102 102 102 102 102 102 102 102 103 102 102  0.2H   12-20-85     178 102 103 102 102 102 102 102 102 102 102 102  0.2H   12-27-85     185 102 102 102 102 102 130 102 102 102 102 105  5.0H   1-03-86     192 113 108 102 102 107 105 102 102 102 102 105  3.0__________________________________________________________________________ .sup.a Serum samples were analyzed at Research Triangle Institute using radioimmunoassay.