USE OF ASYMMETRIC MEMBRANES IN DELIVERY DEVICES

摘要

A device for controlled release of an active substance through one or more asymmetric membranes by diffusion and/or osmotic pumping. The active substance may typically be a pharmaceutically active substance such as antihypertensive and antianxiety agent to be released into the fluid of the gastrointestinal tract of an animal over a prolonged period of time. The asymmetric membranes may be permeable and made of for example a cellulose ester or ethyl cellulose. The active substance may be released by osmotic pumping or by diffusion. Also disclosed is a process for producing the device by a phase inversion process. The asymmetric membrane is comprised of two membrane layers, one being a relatively thick and very porous substructure and the other being a very dense thin skin.