Retard systems for the sustained release of medicinal and/or bio

Details Retard systems for the sustained release of medicinal and/or bio Retard systems for the sustained release of medicinal and/or bio

1993-10-18

1996-07-23

Webman, Edward J.

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Matrices

424434, 424435, 424501, 424DIG13, 428480, A61K 4734, A61K 910, A61K 914

Patent

active

055387381

DESCRIPTION:

BRIEF SUMMARY
This application is a 371 of PCT/EP92/00825 filed Apr. 11, 1992.


BACKGROUND OF THE INVENTION

1. Field of the Invention
The invention relates to a development in the field of sustained release systems of active substances, more particularly in the area of medicinal and/or biological valuable materials from a carrier material.
2. Statement of Related Art
Combination materials of this kind are the subject matter of numerous recent investigations and printed publications in both the fields of pharmaceutical auxiliary materials and of biological preparations, for example crop protection chemicals. They are designated by terms such as retard systems, depot or slow release materials, respectively, or quite generally as mixtures of active substances providing a sustained release of the valuable materials.
Depot materials of this kind usually consist of a carrier with or without any activity of its own, in which an active substance, the release of which is to be sustained, has been incorporated. In recent literature particular attention has been given to polymer compounds based on polyesters of lower hydroxycarboxylic acids as carrier materials, more specifically those having from 2 to 6 carbon atoms in the hydroxycarboxylic acid molecule. Carrier materials of this kind are prone to undergo hydrolysis and are subject to biological degradation mechanisms. The corresponding polyesters derived from glycolic acid, lactic acid and/or hydroxybutyric acid having restricted molecular weights are of particular importance.
Among the more recent pertinent literature, reference may be made, for example, to U.S. Pat. No. 4,011,312, which discloses solid formulations of copolyesters of glycolic acid and lactic acid, having molecular weights of below 2,000, as a carrier material in admixture with antibiotically active substances such as tetracycline, neomycin and other antibiotics for the treatment of bovine mastitis at room temperature or body temperature. The preparation of lower molecular weight poly(.beta.-hydroxybutyrate, PHB) and the use thereof as a solid carrier material for the formulation of sustained release tablets containing a pharmaceutically active substance has been described in "Die angewandte makromolekulare Chemie" 161 (1988), 1-8 (No. 2604). Upon the investigation of the release kinetics it has been shown, in the case presented here, that the amount of the active ingredient released is highly dependent on the molecular weight of the PHB fraction, the retardation in the release of the active substance being increased with the decrease in the molecular weight.
Numerous investigations deal with the use of resorbable polyesters based on glycolic acid/lactic acid as a carrier material for the sustained release of the active substance when used in combination with medicinal valuable materials, crop protection agents and the like. Reference may be made, e.g., to D. L. Wiese et al. in: "Drug Carriers in Medicine", Academic Press, London 1979, pp. 237-270, and to the literature quoted therein re retard forms of drugs; R. L. Kronenthal, Polym. Sci. Technol. 1975, 8 (Polym. Med. Surg.), 119-137.
The manner of the release of the active substance is affected, on the one hand, by the interaction between the active substance and the carrier material while, on the other hand, it is highly dependent on the structure and the properties of the usually polymeric carrier material. For example, the active substance may be micro-encapsulated in the polyesters of the type mentioned, it may be embedded in the polymer matrix, or it may be bonded to the terminal groups.
Thus, the release of the active ingredient proceeds via different mechanisms depending on the formulation. In the case of encapsulated active substances the diffusion of the active substances through micropores in the envelope plays an important role. If the active substances are dispersed or dissolved in a solid polymer matrix, the release of the active ingredients is governed by the diffusion through the matrix, by the hydrolytic erosion of the matrix or by a combin

REFERENCES:
patent: 4322398 (1982-03-01), Reiner et al.
patent: 4626310 (1986-12-01), Ritter

Affiliated with

Also associated with

Rating

Retard systems for the sustained release of medicinal and/or bio does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Retard systems for the sustained release of medicinal and/or bio, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Retard systems for the sustained release of medicinal and/or bio will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-711392