Characteristic of indomethacin and naproxen release from silastic polymeric rods in vitro

In this study naproxen was released more rapidly than indomethacin from silastic rods in vitro, the periods of release being approximately 5 days and 20 days respectively. The release rate was dependent upon several factors including the initial concentration of the anti-inflammatory compound in the rod, the dimensions of the rods, and the pH of the buffer. Incorporation of albumin or fumed silica reduced only slightly the rate of release of indomethacin from the rods. The most significant way found for extending the period of release was to cover the silastic rods with a low permeability polyvinyl sleeve.