Polylactic acid-based implant susceptible of bioresorption conta

Details Polylactic acid-based implant susceptible of bioresorption conta Polylactic acid-based implant susceptible of bioresorption conta

1993-12-08

1996-10-22

Azpuru, Carlos

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Implant or insert

424489, 424501, 5147723, 514963, 514965, A61F 202, A61K 914, A61K 950, A61K 4732

Patent

active

055674313

DESCRIPTION:

BRIEF SUMMARY
The subject of the present invention is an implantable and bioresorbable pharmaceutical composition based on poly(lactic acid), intended especially for implementing a local internal antibiotherapy.
It is known that the pharmaceutical industry is currently looking for new implantable medicinal forms, which progressively release the active principle, with the aim of overcoming the faults of the conventional pharmaceutical forms and in particular of avoiding the necessity for repeated administrations.
Controlled-release systems are generally micro-capsules, microspheres or bulk implants of various forms, for example cylindrical forms (needles). In these systems, the active principle is generally dispersed in a bioresorbable polymer matrix.
Among bioresorbable polymers, poly(lactic acid)s are the most used. The literature provides varied examples of application of such systems, especially to anti-cancer chemotherapy and to hormonotherapy.
In the field of antibiotherapy, poly(lactic acid) microspheres containing erythromycin have already been described. These microspheres are administered by parenteral injection and act systemically, with progressive release of the antibiotic, while reducing irritation of the tissues at the point of injection; see P. K. Gupta et al., 5th Congr. Int. Technol. Pharm., 4, 73-79, 1989.
However, microspheres do not constitute a satisfactory form of administration, on the one hand because they contain residues of surface-active agents used in their preparation and, on the other hand, because they generally contain a thin polymer layer at the surface which is free of active substance, which at first delays the release of this substance.
The subject of the present invention is an implantable pharmaceutical composition intended in particular for implementing a not general, but local, antibiotherapy, essentially restricted to sites of operations, in order to prevent and/or cure local infections which must always be feared after a surgical operation.
Systemic antibiotherapy with broad-spectrum antibiotics administered parenterally is currently used to prevent these infections. The disadvantages of general antibiotherapy are known: painful injection with irritation of tissues, renal or hepatic toxicity and the necessity for repeated administrations.
The subject of the present invention is to overcome these disadvantages by making available to the surgeon a bioresorbable composition, intended to be implanted at the site of operation, before suturing the wound and making it possible to implement a local internal antibiotherapy by progressive release of the antibiotic substance. Of course, the bioresorbable composition of the invention, intended to provide a local antibiotherapy affecting the site of operation, is mainly deployed in contact with soft internal tissues accessible via the wound. It can also be placed on the contact surface between a bulk bone implant (especially osteosynthesis component) and the bone cavity intended to receive this implant.
For ease of such a use, the composition of the invention is provided in the form of a powder or thin film. The powder is a powder obtained by grinding a dispersion of the antibiotic in the polymer matrix, which makes it possible to avoid the disadvantages, indicated above, of the microspheres.
In fact, it has been discovered that compositions in the ground powder or thin film form make it possible to obtain a satisfactory release profile, with an initial phase of rapid and strong release (or "burst") of the antibiotic present at the surface, making it possible to obtain a suitable attack dose, followed by a phase of slower release of the antibiotic over a sufficiently long period of time, for example about ten days.
In the compositions of the invention, degradation of the polymer matrix is relatively slow with respect to the period of release of the antibiotic, in order that this release is controlled by dissolution/diffusion phenomena of the antibiotic in the external medium, and not as a result of the degradation of the matrix.
Another char

REFERENCES:
patent: 4719246 (1988-01-01), Murdoch et al.
patent: 5180765 (1993-01-01), Sinclair

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