Controlled release of morphine from a poloxamer 407 gel.

Treatment of painful ulcers is discouraging. Topical morphine has been described as a useful therapeutic adjunct in some patients. In the development of a new analgesic product, we studied the in vitro release characteristics of a new topical formulation containing 0.5% (w/w) morphine-HCl in a poloxamer 407 (P407) based gel. A diffusion cell was used for measurement of in vitro release characteristics. The donor compartment (DC) and the receptor compartment (RC) were separated by a 5000 Da cellulose acetate membrane. The morphine-HCl release from this developed P407 based gel followed zero-order kinetics with a constant release of 150 μg cm(-2)h(-1). Our results support the use of this P407 gel as a sustained release topical formulation in the pharmacological treatment of painful ulcers. Future research welcomes a formulation with release characteristics leading to less frequent application.