Asymmetric membrane capsules for osmotic drug delivery: I. Development of a manufacturing process

This paper describes a novel non-disintegrating polymeric capsule and a manual and a semi-automatic process developed for its manufacture. The capsule wall was made by a phase inversion process in which the membrane structure was precipitated on stainless steel mold pins by dipping the mold pins into a coating solution containing a polymer–solvent–nonsolvent system followed by dipping into a quench solution. The resulting asymmetric membrane wall was composed of a thin dense region supported on a thicker porous region. The asymmetric membrane capsules can be filled with a blend of the active agent and excipients for use in osmotically modulated controlled drug delivery applications.