The aim of present study was to convert valacyclovir HCl (VH) into effervescent gastro retentive floating tablet (GRFT) and simultaneously to optimize the ratio of two grades of the synthetic polymer: hydroxy popyl methyl cellulose (HPMCK100M and HPMC K4M), in extending the release of VH until 12 h. The drug- excipients compatibility studies of VH and the polymers were carried by FTIR studies. The effervescent GRFT of VH was prepared by direct compression method. All Formulation blends and tablets were evaluated for pre-compression, post-compression, in vitro buoyancy studies and the optimized formulation was undergone accelerated stability studies for 3 months. The drug-excipients compatibility studies reveal that VH and the polymers used are compatible. Evaluation parameters were within the acceptable limits for all formulations. The drug release kinetics of optimized formulation F6 fitted best to the Zero-order (R2= 0.999). The (R2= 0.883) value in case of Higuchi release was found to be nearer to 0.9, suggesting that the drug release process is predominantly by diffusion. Korsmeyer-Peppa’s diffusion exponent value (n=0.972) for cylindrical shape, suggested the release mechanism of the drug is by Super Case II transport (as n > 0.89). Hence the ratio of HPMCK100M : HPMC K4M in 1:1 proportion is the optimized ratio and at the conc. of 10% w/w of each polymer, in better extending the release of VH until 12 h from its effervescent GRFT , to localize the drug at upper part of GIT, for improved absorption and oral bioavailability.
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