Preparation and in vitro evaluation of a multiple-unit floating drug delivery system based on gas formation technique

A multiple-unit floating drug delivery system based on gas formation technique was developed in order to prolong the gastric residence time and to increase the overall bioavailability of the dosage form. The system consists of the drug-containing core pellets prepared by extrusion–spheronization processes, which are coated with double layers of an inner effervescent layer (sodium bicarbonate) and an outer gas-entrapped polymeric membrane of an aqueous colloidal polymer dispersion (Eudragit® RL 30D, RS 30D, NE 30D). Only the system using Eudragit® RL 30D as a gas-entrapped polymeric membrane could float. The time to float decreased as amount of the effervescent agent increased and coating level of gas-entrapped polymeric membrane decreased. The optimum system could float completely within 3 min and maintained the buoyancy over a period of 24 h. The drug release was sustained and linear with the square root of time. Increasing coating level of gas-entrapped polymeric membrane decreased the drug release. Both the rapid floating and the sustained release properties were achieved in the multiple-unit floating drug delivery system developed in this present study.