Comparison of in situ gelling formulations for the oral delivery of cimetidine

Three liquid formulations with in situ gelling properties have been assesse d for their potential for the oral delivery of cimetidine. The formulations were dilute solutions of: (a) enzyme-degraded xyloglucan. which form therm ally reversible gels on warming to body temperature; (b) gellan gum and; (c ) sodium alginate both containing complexed calcium ions that form gels whe n these ions are released in the acidic environment of the stomach. The in vitro release of cimetidine from gels of each of the compounds followed roo t-time kinetics over a period of 6 h. Plasma levels of cimetidine after ora l administration to rabbits of each of the formulations were compared with those resulting from administration of a commercial cimetidine/alginate sus pension with an identical drug loading. In vivo release characteristics of each of the in situ gelling formulations were similar to those of the comme rcial preparation. (C) 2001 Elsevier Science B.V. All rights reserved.