Preparation and Evaluation of Heat-sensitive Melting Gel

Abstract

The aim of the present study was to prepare a heat-sensitive melting gel using κ-carrageenan and gelatin as the gelation agents. The two agents have similar melting points (40-50°C for κ-carrageenan and 20-30°C for gelatin). When mixed together, they have a coexisting grid structure, which is favorable for the preparation of a gel with a melting temperature close to the human body temperature. Gel preparation showed a clearly different melting behavior from that of many other compounds and began to soften significantly below its melting temperature.κ-carrageenan at 0.5% may thus be the preferred concentration because preparations having a melting temperature just below the human body temperature are easy to chew, with a rapidly decreasing viscosity. We studied the plasma concentrations of acetaminophen as a function of time after the oral administration of a bulk powder or gel preparation of acetaminophen to rabbits after overnight fasting. A comparison of the AUC for both oral and intravenous administration indicated the bioavailability of acetaminophen gel to be about 90%. The heat-sensitive acetaminophen melting gel prepared using κ-carrageenan and gelatin thus shows promise for clinical use because of its favorable physicochemical and pharmaceutical characteristics.