FORMULATION AND CHARACTERIZATION OF CONTROLLED POROSITY OSMOTIC TABLETS OF ACYCLOVIR FOR TREATMENT OF HERPES SIMPLEX

The main objective of present work was to formulate and evaluate swellable controlled porosity osmotic tablets of Acyclovir for the treatment of herpes simplex. This formulation aims to release the drug in zero order pattern, increase bioavailability, reduce frequency of drug dosing and hence increased patient compliance. Acyclovir is a synthetic purine nucleoside analogue that is specially activated by Herpes Simplex Virus (HSV) induced thymidine kinase, and inhibits viral DNA polymerases as well as acting as a chain terminator. The technique used for the preparation of tablets was direct compression followed by deep coating of core tablets and total nine formulations (F1-F9) were prepared. Prior to compression, the prepared granules were evaluated for flow and compression characteristics. Prepared osmotic drug delivery system was also evaluated for in vitro drug release study. In vitro release profile of all formulations was in range from 54.12-99.85%. The formulation F2 was best amongst all and showed 56.58% drug release in 12 hr and 98.92% in 24 hrs. Zero order drug release kinetics was shown by formulation F2 at 0-24 hr which is require for enhance bioavailability of acyclovir. Further, among coated formulations (C1-C8), C7 showed sufficient strength and formed smooth surface. The coating did not show any leakage and was stable during dissolution of tablet.  The % weight gain of coated tablet was found to be in range 1.98-2.40%. The thickness of semipermeable membrane was 240 μm and membrane withstands the pressure during the dissolution. The surface morphology of the coating membrane was examined using Scanning Electron Microscopy after dissolution and showing pore formation in membrane. Accelerated stability studies were conducted for optimized formulation as per specified ICH guidelines for one month. Formulations were found to be stable for one month when tested for drug content as well as in vitro dissolution studies.