Process of producing an active agent delivery device

Claim 1

A process of producing an active agent delivery device which releases active agent over a prolonged period of time comprising treating microporous material comprising: (a) a matrix consisting essentially of essentially linear ultrahigh molecular weight polyolefin which is essentially linear ultrahigh molecular weight polyethylene having an intrinsic viscosity of at least about 18 deciliters/gram, essentially linear ultrahigh molecular weight polypropylene having an intrinsic viscosity of at least about 6 deciliters/gram, or a mixture thereof, (b) finely divided particulate substantially water-insoluble filler, of which at least about 50 percent by weight is siliceous, distributed throughout said matrix, said filler constituting from about 50 percent to about 90 percent by weight of said microporous material, and (c) a network of interconnecting pores communicating throughout said microporous material, said pores constituting more than 35 percent by volume of said microporous material with a releasable active agent or precursor thereof to associate at least a portion of said releasable active agent or said precursor with at least a portion of said filler.