MXPA98003452A - Process to manufacture implants containing bioactive peptides - Google Patents

Abstract

A process for manufacturing a pharmaceutical composition for the delivery of an effective amount of a bioactive peptide or peptide analog over a period of 1 to 12 months. This process includes the steps of grinding a copolymer of lactic acid and glycolic acid having a ratio of glycolide to lactide units of from about 0 to 5:1 to a particle size of between about 50 and 150&mgr;m;sterilizing the ground copolymer with a dose of between about 1 and 2.5 Mrads of ionizing&ggr;-radiation;wetting the ground and sterilized copolymer with a sterile aqueous slurry of a bioactive peptide or peptide analog;aseptically blending the copolymer and the slurry to obtain a homogeneous mixture of the copolymer and between about 10 and 50%of the bioactive peptide or peptide analog;drying the mixture at reduced pressure and at temperature not exceeding 25°C;aseptically extruding the dried mixture at a temperature between about 70 and 110°C;and aseptically cutting cylindrical rods of about 1 to 2 mm diameter and between about 10 and 25 mm in length from the extruded mixture to form the pharmaceutical implants.

Description

PROCESS FOR MANUFACTURING IMPLANTS CONTAINING BIKECTJEVOS PEPTIDES TECHNICAL FIELD The present invention relates to a new process for preparing implants of bioactive peptides or peptide analogs, wherein such implants have a more uniform distribution of the peptide or analogue of the peptide. BACKGROUND OF THE INVENTION A wide variety of peptides and bioactive peptide analogs have been used as agents for the treatment of various disorders. These active agents are usually administered in connection with a polymeric distribution system to control the release of the agent. For example, the peptide analogues of the natural hypothalamic hormone LHJRK (Hormone Liberator of Luteinizing hormone, which is a decapeptide), have therapeutic value when administered for a prolonged period with the appropriate distribution system. Commercially successful delivery systems include microspheres, microcapsules, microgranules and other forms of implant which, when injected subcutaneously or intramuscularly, release the LHRH analogue from a biocompatible and biodegradable matrix. The . REF: 27328 glycolic ("PLGA", polylactic glycolic acid), as described, for example, in U.S. Patent Nos. 3,773,919; 3,887,499; 4,675,189; 4,767,628 and many others. It has been assumed that a continuous or monophasic release of such bioactive agents is a highly desirable characteristic of such formulations (see for example, US Patent No. 5,366,734). In fact, it has now been found that what is really necessary is to have the "therapeutic" effect of the peptide or peptide analogue maintained or sustained for a relatively long period (for example, 3 to 6 months or more). Thus, improvements in this area are desirable and necessary. BRIEF DESCRIPTION OF THE INVENTION The present invention relates to a process for the manufacture of pharmaceutical implants for the distribution of an effective amount of a peptide or bioactive peptide analog during a period of 1 to 12 months, which comprises: grinding a copolymer of lactic acid and glycolic acid having a ratio of glycolate units to lactate of about 0 to 5: 1, up to a particle size between about 50 and 150 μm; moisten the crushed and the copolymer with an aqueous slurry of a peptide or bioactive peptide analog, mixing the copolymer and the slurry to obtain a homogeneous mixture of the copolymer and between about 10 and 50% of the bioactive peptide; dry the mixture under reduced pressure and at a temperature not exceeding 25 ° C; Extrude the dry mixture at a temperature between about 70 and 110 ° C; and cutting cylinders of approximately 1 to 2 mm in diameter and between approximately 10 and 25 mm in length from the extruded mixture, to form the implants. Advantageously, the comminuted copolymer is sterilized with a dose between about 1 and 2.5 Mrad of ionizing radiation? before being combined with the bioactive peptide, and the mixing, extrusion and cutting steps are carried out under aseptic conditions. Likewise, implants are usually sterilized in a conventional manner before being administered to the subject or patient. The polymers or copolymers form a biodegradable matrix within which a uniform distribution of the peptide or peptide analogue is contained. In these copolymers an advantageous ratio of glycolate units to lactate units ranges from about 0.5: 1 to 3: 1. A particularly preferred copolymer to be used is soluble in benzene and has an inherent viscosity of 0.51 to 1 (1% in benzene). The amount of slurry preferably is controlled in such a way that the amount of water in the mixture is between 35 and 65 ml per 100 g of copolymer, such that the amount of bioactive peptide in these cylinders is between about 10 and 50% by weight. The peptide or bioactive peptide analog may be an agonist or antagonist of LHRH, of GnRH, growth hormone-releasing hormone, growth hormone-releasing peptide, angiotensin, bombesin, bradykinin, cholecystokinin, enkephalin, neurokinin, tachykinin or of the substance P. The peptide -bioactive can also be an inhibitor such as renin inhibitor, protease inhibitor, metallopeptidase inhibitor, enkephalinase inhibitor and inhibitor of the ventricular or brain natriuretic factor-degrading enzyme. The LHRH analogue is preferably a pharmaceutically acceptable salt of an LHRH agonist or antagonist, such as a pharmaceutically acceptable salt of leuprolide, goserelin, triptorelin, buserelin, avorelin, deslorelin, histrelin, cetrorelix, teverelix, ramorelix, antide, nictide , azaline B, azaline C or ganirelix.

Another aspect of the present invention relates to pharmaceutical implants obtained in accordance with the process defined herein. These implants are preferably contained in a device for retractable needle implants, which are suitable for subcutaneous injection under the skin of a mammal. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a graph of serum testosterone and avorelin plasma levels of male beagle dogs for up to 180 days after injection of avorelin of Example 1 of the invention; and Figures 2 and 3 are graphs of serum levels of LH, FSH and testosterone in male patients for up to 33 to 35 weeks after the injection of avorelin implants of Examples 2 and 3 of the present invention. DETAILED DESCRIPTION OF THE PREFERRED MODALITIES Any polylactide polymer or PLGA copolymer can be used to form the biodegradable matrix of the present invention. These materials are well known to those skilled in the art, for example in the aforementioned US Patents, and need not be further described herein. The particular copolymer is selected and then ground to a particle size of between approximately 50 and 150 μm. This crushing stage is also conventional and does not need further explanation. In the most preferred method, the comminuted copolymer is sterilized at a dose of between about 1 and 2.5 Mrad ionizing radiation, again, in a conventional manner that is known to those skilled in the art. The comminuted and sterilized copolymer particles are subsequently wetted with a sterile aqueous slurry of an active agent of a peptide or bioactive peptide analogue. This slurry is prepared by combining the peptide, peptide analog or a pharmaceutically acceptable salt thereof, with sterile water. The amount of the active agent can vary over a wide range, from for example about 5 to 50, and preferably about 10 to 25 g per liter. Then, the solution is sterilized in the conventional manner, for example by passing it through a sterilization filter. If necessary, the solution can be concentrated to increase the amount of peptide or peptide analogue therein. The concentration of the peptide or peptide analogue in the solution can be varied to change the dose resulting from the implant. Next, the copolymer and the grout are Aseptically mixed to obtain a homogeneous mixture of the copolymer and the active agent. Depending on the desired formulation, the active agent represents between about 10 and 50% and preferably about 15 to 25% of the mixture. As noted above, a water content of about 35 to 65 ml and preferably about 45 to 55 ml per 100 g of copolymer in the mixture is desirable. Subsequently, the mixture is dried under reduced pressure and at a temperature not exceeding 25 ° C, to form the pharmaceutical composition. If necessary, this composition can be formulated with conventional vehicles to obtain an injectable suspension. Alternatively, the dried composition can be extruded with a conventional extrusion apparatus at a temperature between about 70 and 110 ° C, to form a "spaghetti" or continuous cylinder. The use of heat in the extrusion lid helps dry the product more. To form the implants, these cylinders are aseptically carried in pieces of approximately 1 to 2 mm in diameter and between 10 and 25 mm in length. The length of the implant is another mechanism for varying the dose of the peptide or bioactive peptide analogue. These products can be implanted subcutaneously below the skin of the patient, using the devices of conventional implants. The present invention provides an effective release (ie, in terms of therapeutic effectiveness) of a peptide or bioactive peptide analog., such as an LHRH analog, even if such release, measured in plasma concentration of the peptide or peptide analog, is intermittent or discontinuous. This effectiveness can be achieved, for example, by internalization or down regulation of pituitary receptors after exposure to LHRH agonists or LHRH antagonists, which have intrinsically long-acting. The process of the present invention can be applied to a wide variety of peptides or peptide analogues. In addition to the LHRH analogue mentioned herein, GnRH or hormones or growth hormone releasing peptides may be mentioned. Generally, any peptide or peptide analogue which is chemically stable under the conditions of the process and which provides a sustained release is desirable from a therapeutic point of view. Non-limiting examples of such peptides and peptide analogues are somatostatin and somatostatin analogs, angiotensin II agonist and antagonist analogues, bombesin analogues, preferably antagonists of the bombesin, bradykinin antagonists, preferably with minimal histamine release properties, cholecystokinin analogs, preferably cholecystokinin antagonists, encephaloid analogues, neurokinins, tachykinins and substance P antagonists, renin inhibitors and other aspartyl protease inhibitors , such as HIV protease inhibitors, metallopeptidase inhibitors such as angiotensin converting enzyme, enkephalinase inhibitors and inhibitors of the ventricular or brain natriuretic factor-degrading enzyme. Those skilled in the art will favor those peptides and peptidomimetic compounds that are not absorbed or that are poorly absorbed by the oral route, in animals and humans, and will adjust the dose of the compound formulated in the implants of the present invention according to the power biological of such compound, at the effective daily dose required and the estimated duration of release of the formulation. The present invention also eliminates contamination of such formulations with organic solvents, particularly chlorinated ones, such as chloroform or methylene chloride, which are typically used in the manufacture of microspheres or microcapsules by the method of coacervation-evaporation. of solvents (see for example U.S. Patent No. 3,773,919) or solvents that are used to sterilize PLGA copolymers by filtration. The present invention does not use any organic solvent, but takes advantage of the unorthodox use of water, a solvent that until now was considered unacceptable for such formulations, due to its deteriorating effect on the polyester (copolymer) of the PLGA matrix, where it can accelerate chemical hydrolysis and also damage the structural integrity when exposed to ionizing radiation (formation of free radicals) during the necessary sterilization stage for safety reasons. Another advantage of this unorthodox use of water is to achieve a uniform coating of the active ingredient on the crushed polymer powder, obtaining a highly necessary and highly desirable uniformity of the mixture, which is an essential condition of the manufacturing process. An unexpected advantage of this unconventional solvent is the "wettability" of the powder mixture, which would otherwise create serious problems due to the formation of static electric charges, which can cause unacceptable mechanical losses and loss of uniformity.

The process of the present invention further provides a simple method of sterilization of the composition, subjecting the polymer to ionizing radiation before mixing it with the peptide or bioactive peptide analogue, which invariably is damaged by radiation, obtaining undesirable byproducts. An additional advantage of the process of the present invention is that a variable radiation sterilizing dose (1 to 2.5 Mrad) predetermined by the actual biomass present in the copolymer can be used, which results in a safety without undue creation of artifacts by radiolysis. EXAMPLES The following Examples are presented to illustrate the effectiveness of the most preferred formulations of the present invention. EXAMPLE 1 The manufacturing process was carried out on a commercially available insulator (ARFL, Neuilly-sur-Marne, France) equipped with air passages for the introduction of presterilized components, and the apparatus itself is sterilized by an acid pretreatment peracetic The extrusion machine is a commercially available single screw extruder (Brabender, 47055 Duisburg, Germany) equipped with probes of pressure and temperature. The cutting machine is also available commercially (Davis-Standard Corp. Cedar Grove, N.J., USA). The mixers and weighing instruments are conventional equipment. An amount of 80 g of racemic lactic acid and glycolic acid copolymer (75:25) soluble in benzene and with an inherent viscosity of 0.60 (1% in benzene) (PuracBioche B.V., Gorinchem, The Netherlands) is crushed and sieved to collect the particle fraction between 50 and 150 μm and sterilized with ionizing radiation? of 1.5 Mrad in a commercial laboratory (Caric-Mediris, Fleurus, Belgium) and introduced through the air inlet to the sterile isolator. Separately, 23 g of the LHRH analog of avorelin acetate (INN), or (2-methyl-D-Trp) acetate (des-Gly) (Proethylamide) LHRH, are dissolved in 500 ml of sterile water and filtered through a Millipore sterilizing filter 0.2 μm. The sterile solution is reduced by evaporation to a volume of 50 ml and the resulting mixture is dispersed in the ground copolymer. The wet mixture is mixed to obtain a granulate containing 20% avoreline. Such a mixture is dried at 25 ° C under reduced pressure and then extruded at a temperature gradient of 70 to 110 ° C, at pressures of 3500 psi. The resulting extrudate is aseptically cut to obtain cylinders of 1.5 mm in diameter and 15 mm in length, containing 10 mg of avoreline, which are inserted in a pre-sterilized implanter with retractable needle (SFM GmbH, D-6480 Wachtersbach, Germany) sealed and used as such, functionally sterilized additionally with a dose of 1.5 Mrad or radiation? before its clinical use. After subcutaneous implantation in male beagle dogs, after the initial stimulation of LH and testosterone, testosterone castration levels were maintained for 6 months. The plasma concentration of avoreline, after this short duration increase, decreased to a nadir at 40 days and rose again at 120 days before becoming undetectable at day 160. These results are shown in Figure 1. EXAMPLE 2 Following essentially the procedure of Example 1, avorelin 10 mg implants were prepared, sterilized further and healthy male patients implanted. After the initial stimulation of LH, FSH and testosterone, these levels were significantly reduced, maintaining the testosterone level below a castration level for 33 weeks. These results are shown in Figure 2.

EXAMPLE 3 The procedure of Example 2 was essentially followed, except that longer implants were prepared to provide a dose of avorelin of 15 mg. These implants were sterilized and implanted in healthy male patients. After the initial stimulation of LH, FSH and testosterone, these levels were significantly reduced, maintaining the testosterone level below a castration level for 33 weeks. These results are shown in Figure 3. EXAMPLE 4 Following essentially the procedure of Example 1 with the appropriate modifications necessary for the individual analog of LHRH, cylinders containing 22 mg leuprolide were obtained in a similar manner, mg of goserelin and 30 mg of teverelix. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as an antecedent, what is contained in the following is claimed as property.

Claims (12)

1. CLAIMS 1. A process for the manufacture of pharmaceutical implants for the distribution of an effective amount of a peptide or bioactive peptide analog during a period of 1 to 12 months, characterized in that it comprises: grinding a copolymer of lactic acid and glycolic acid having a ratio of glycolate units to lactate units of about 0 to 5: 1, up to a particle size of between 50 and 150 μm; moistening the crushed and sterilized copolymer with a sterile aqueous slurry of a bioactive peptide or peptide analogue; mixing the copolymer and the slurry to obtain a homogeneous mixture of the copolymer and an amount between about 10 and 50% of the peptide or bioactive peptide analogue; dry the mixture under reduced pressure and at a temperature not exceeding 25 ° C; extruding the dried mixture at a temperature between about 70 and 110 ° C; and cutting forming cylinders of approximately 1 to 2 mm in diameter and between 10 and 25 mm in length, from the extruded mixture, to form the implants.
2. 2. The process in accordance with the claim 1, characterized in that it further comprises sterilizing the ground copolymer with a dose between about 1 and 2.5 Mrad of ionizing radiation? before adding the aqueous slurry to it.
3. 3. The process according to claim 1, characterized in that it further comprises carrying out the steps of mixing, extruding and cutting in "aseptic conditions." 4.
4. The process according to claim 1, characterized in that it also comprises selecting the copolymer a 5.
5. The process according to claim 1, characterized in that the quantity of slurry is controlled in such a way that the amount of slurry is controlled in such a way that the amount of slurry is controlled in such a way that of water in the mixture is about 35 to 65 ml per 100 g of copolymer 6.
6. The process according to claim 1, characterized in that the amount of slurry is controlled in such a way that the amount of peptide or peptide analog. bioactive in the cylinders is between 10 and 50% by weight 7.
7. The process according to claim 1, characterized in that the ratio of glycolate units with respect to lactate in the copolymer, ranges from about 0.5: 1 to 3: 1.
8. The process according to claim 1, characterized in that the peptide or bioactive peptide analogue is an agonist or antagonist of LHRH, GnRH, growth hormone releasing hormone, growth hormone releasing peptide, of angiotensin, bombesin, bradykinin, cholecystokinin, enkephalin, neurokinin, tachykinin or substance P.
9. 9. The process according to claim 1, characterized in that the peptide or analogue of the bioactive peptide, is a renin inhibitor, a protease inhibitor, a metallopeptidase inhibitor, an enkephalinase inhibitor and an inhibitor of the ventricular or brain natriuretic factor-degrading enzyme.
10. The process according to claim 8, characterized in that the peptide or bioactive peptide analog is a pharmaceutically acceptable salt of leuprolide, goserelin, triptorelin, buserelin, avorelin, deslorelin, histrelin, cetrorelix, teverelix, ramorelix, antide, nictida, azaline B, azaline C or ganirelix.
11. 11. A pharmaceutical implant characterized in that it is obtained in accordance with the process of any of the preceding claims.
12. 12. The pharmaceutical implant according to claim 11, characterized in that it is contained in an implant device with a retractable needle and that it is suitable for subcutaneous injection under the skin of a mammal.