Manufacture and characteristics of asymmetric membrane capsule shells with a novel wet phase inversion method

In order to overcome the difficulty in stripping and to improve the automaticity and efficiency, a novel method was developed to prepare asymmetric membrane capsule shells (AM-CSs). Soluble mold pins were used to replace conventional insoluble mold pins, and simplified process was designed. Investigated by scanning electron microscopy and dye test, the homemade AM-CSs had typical asymmetric structure, in situ pore formation ability and high water influx. The in vitro dissolution properties of AM-CSs and homogeneous membrane capsule shells (HM-CSs) were compared. The release behavior of Metoprolol Tartrate and Nimodipine from the AM-CSs was mainly dominated by osmosis, while no drug could release from HM-CSs. The novel wet phase inversion method had significant advantages as well as potential value to be used in pharmaceutical research and application.