Enhanced gastric residence time of acyclovir by floating raft formulation using box-behnken design

This research paper reports enhancing Acyclovir's gastric residence time by implementing a raft-forming drug delivery system. Because acyclovir is a narrow absorption window drug, it has a poor bioavailability of 10-20 % and a short half-life (t_1/2) of 2.5 h. The guar gum and GMS-based floating raft formulation retain the drug in the stomach for an extended period by enhancing GRT. The Box-Behnken design is used to optimize the amount of guar gum, glyceryl monostearate, and calcium carbonate and to study how they affect the in vitro gelation time, viscosity, and in vitro drug release. The ratio of drug and excipients in guar gum (1:0.5), GMS (1:1.25) based FRF suspension containing sodium citrate (0.25 %), carbopol (0.1 %), and calcium carbonate (1:1.5). Seventeen runs were developed through the Box-Behnken design to study all the optimal interactions between variables and responses through a polynomial equation. The optimized formulation is then characterized using various physicochemical tests such as rheological analysis, in vitro drug release, kinetic drug release, and in vitro permeation studies. The in vitro gelation time, viscosity, and in vitro drug release time of optimized FRF are 12 s, 1090 cps, and 88 % at 24 h, respectively. The flux and permeability coefficient of the optimized batch have a higher value indicating higher permeability of acyclovir. The FRF follows non-fickian diffusion as a drug release mechanism. The results show that the raft-forming drug delivery system significantly enhances the absorption of Acyclovir by prolonging drug release and also improving its gastric residence time in the stomach. This research contributes to the field of drug delivery systems by providing a novel approach for improving the therapeutic efficacy of acyclovir and potentially other drugs with similar characteristics.