Biodegradable, controlled-release microspheres and process for p

Details Biodegradable, controlled-release microspheres and process for p Biodegradable, controlled-release microspheres and process for p

1996-10-11

1998-03-31

Page, Thurman K.

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Implant or insert

424489, 424 932, 424470, 424424, 424425, A61F 200

Patent

active

057335672

DESCRIPTION:

BRIEF SUMMARY
This application is a 371 of PCT/FR95/00485 filed Apr. 13, 1995.
The present invention relates to the production of biodegradable microspheres based on hydrophilic, pharmacologically active compounds, enabling a controlled and sustained release of said active substance to be effected irrespective of the administration route adopted (for example administration by injection).
A large number of pharmaceutical dosage forms based on biodegradable and biocompatible polymers or copolymers have already been described in the prior art. These various forms are obtained by processes whose specificity is always closely linked: dosage form), particular its solubility, its thermostability and its melting point, molecule.
In most applications, the ocular, dermal, auricular and oral routes, it is not necessary to develop small-sized pharmaceutical dosage forms. Accordingly, the processes of melting-extrusion, nebulization, fluidization and even tableting on a conventional tableting machine are very widely described and used.
For implantable pharmaceutical dosage forms, the manufacturing processes are also numerous, since the size of the implant does not necessitate a very large drop in particle size, and hence the processes mentioned above are to be found.
On the other hand, for dosage forms intended for parenteral administration, the manufacturing processes are very strongly linked to the following constraints: able to be administered in the form of an injectable suspension by a suitable syringe (18 to 22 gauge). This makes it necessary to take account of this constraint and to obtain microcapsules or microspheres smaller than 150 .mu.m in size, solubility (water-soluble, fat-soluble) which conditions, for liquid-medium processes, the direction of the simple or multiple emulsions, conditions at the same time the duration of the activity of the product.
In spite of these constraints, which are sometimes very hard to overcome, there is a wide variety of microencapsulation processes, among which there may be mentioned:
The subject of the present invention relates to the production of microspheres based on a hydrophilic molecule, by a process of the multiple emulsion-evaporation of solvent type.
Generally speaking, in a process of this type entailing a W/O/W multiple emulsion and evaporation of the solvent, the water-soluble active principle is solubilized in the first place in the internal phase of a first, W/O emulsion and then, in a second stage, this first emulsion is in its turn emulsified in an external aqueous phase.
This technique has proved especially advantageous for formulating very water-soluble active principles, for which it gives a good efficiency of encapsulation.
The physical principle of multiple emulsion for encapsulating water-soluble active principles has, for example, been described in U.S. Pat. No. 3,523,906.
The present invention relates to a process for preparing a pharmaceutical composition in the form of microspheres affording controlled release of at least one water-soluble active principle, characterized by the following succession of steps: with a solution of at least one matrix copolymer of the dl-lactide-co-glycolide type in a chlorinated hydrocarbon containing, in addition, a release-modulating agent which is a low molecular weight polylactide, leading to a first, microfine and homogeneous emulsion, aqueous phase containing a surfactant, recovered after filtration, washing and drying.
Other features and advantages will become apparent on reading the detailed description given below, in particular with the aid of a few particular examples of implementation.
This invention consists in producing pharmaceutical compositions, in the form of microspheres, intended for obtaining a controlled and sustained release of a water-soluble active principle, according to a process entailing W/O/W multiple emulsion and extraction-evaporation of the solvent, in which, according to a particular feature that consists in using a continuous evaporation system consisting of an incline of appropriate length over whi

REFERENCES:
patent: 5326484 (1994-07-01), Nakashima et al.
patent: 5376347 (1994-12-01), Ipponmatsu et al.
patent: 5389377 (1995-02-01), Chagnon et al.

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