Controlled release gelatin capsules - in which the gelatin shell is insolubilized with a crosslinking agent

摘要

New capsules provide for the controlled release through the capsule walls of therapeutic agents they contain. The capsule walls contain crosslinked gelatin which is insoluble in basic and acidic body fluids. The gelatin may be hard or soft the gelatin. The new capsules can be produced by existing encapsulation technology with very little modification. The sustained release characteristics of the capsules are independent of the pH of the surrounding body-fluid, so that therapeutic agent continues to be released in a controlled manner throughout the passage of the capsule through the gastro-intestinal tract. In an example, commercial hard-shell gelatin capsules are insolubilised by treating with a 1% solution of glutaraldehyde in 0.05-M phosphate buffer pH 7. After washing and drying, the capsules are filled with 37 mg amitriptyline hydrochloride, then the two capsule halves are sealed together with an epoxy resin. The rate of release of active substance from the capsule in water is 3.5 mg/hr. on average.