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Design and Optimization of Floating Drug Delivery System of Valacyclovir Hydrochloride

Ravi Savalam, Rajesh Akki, Munagala Gayatri Ramya and V. Vasu Naik

Valacyclovir hydrochloride (VCH) is L-valyl ester prodrug of acyclovir. VCH degrades in intestinal fluid. The objective was to develop floating microspheres of VCH to localise the drug at upper part of GIT, for improved absorption. The aim of present study was to develop gastro-retentive floating tablet of Valacyclovir hydrochloride by direct compression method. Floating tablets of Valacyclovir hydrochloride was developed by using gas forming agents like sodium bicarbonate and polymers used HPMC K4M, Carbopol 934, and Gaur Gum by effervescent technique. Various combinations of floating polymers were used in this formulation. The floating tablets were evaluated for uniformity of weight, hardness, friability, drug content, in vitro buoyancy, buoyancy lag time and dissolution studies. Formulation F7 containing HPMCK4M (30%) with ethyl cellouse and NaHCO3 has gas generating agent, showed minimal floating lag time and remained afloat throughout dissolution period, while extending the drug release up to 12 hrs, following zero order kinetics. Optimized formulation F7 showed no significant change in physical appearance, drug content, floatability after storage at 45°C/75% RH for three months. The result of the studies showed that floating tablet containing HPMC K4M was most likely to provide targeting of valacyclovir HCl for local action in the colon.