Approaches for developing acyclovir gastro-retentive formulations using hot melt extrusion technology

The aim of the current study was to prepare and compare acyclovir (ACV) floating gastro-retentive formulations synthesized via hot-melt extrusion (HME) techniques using pressurized CO2 and sodium bicarbonate. Physical mixtures of ACV (20%, w/w) and HPC EF (70%, 60%, w/w) with HPC MF (10%, w/w) or HPMCAS-LG (10%, w/w) were prepared using a co-rotating twin-screw extruder with a standard screw configuration. Additionally, P-CO2 was injected into 9th zone of the extruder, or NaHCO3 was added (10% w/w). In vitro dissolution studies were performed in 0.1 N hydrochloric acid medium, and all formulations floated on the medium because of their porosity and low density. Formulations with NaHCO3 (F9, F10) showed better sustained release potential than the counterparts with P-CO2 (F7, F8). Accelerated stability studies demonstrated similar release, with f(2) values above 50, indicating no significant differences between fresh samples and stability samples. Altogether, the ACV floating gastro-retentive formulations were successfully developed, which can prolong the gastric residence time to enhance the therapeutic efficacy.