The affinity of a drug to serum albumin has influence on the pharmacokinetics of a drug. In the present study, the mutual interaction of metformin hydrochloride (MET) with bovine serum albumin (BSA) was investigated using fluorescence spectroscopy under different conditions. It was observed that the fluorescence  quenching of BSA by metformin hydrochloride is a result of the formation of metformin hydrochloride- BSA complex with probable involvement of tryptophan residue. Fluorescence quenching constants were determined using  the Stern- Volmer equation and Van’t Hoff equation to provide a measure of the thermodynamic parameters ?G, ?H, and ?S at different temperatures indicating that the hydrogen bond and the hydrophobic forces play a major role for metformin hydrochloride- BSA association. DOI: http://dx.doi.org/10.3329/dujps.v11i1.12486 Dhaka Univ. J. Pharm. Sci. 11(1): 45-49, 2012 (June)

The aim of the present study was to improve the solubility and dissolution rate of atorvastatin (ATV), a slight water-soluble drug, by solid dispersion (SD) technique using a hydrophilic carrier Poloxamer 188 (POL188). Physical mixing (PM) and solvent evaporation (SE) method were used to prepare ATV-SD where different drug-carrier ratios were used. Prepared formulations were characterized in their solid state by solubility study; differential scanning calorimetry, scanning electron microscopy, and Fourier transform infrared spectroscopy which demonstrated changes in the formulations supporting the improved solubility. Percent content of POL188 in the SD matrix was found to play the pivotal role in the improvement of dissolution property of ATV. In case of PM, highest enhancement in drug release was found for 1:3 ratio (P < 0.05, ANOVA Single factor) whereas in case of SE, 3:0.5 ratio of ATV-POL188 resulted the maximum enhancement in ATV release (P < 0.05, ANOVA Single factor). Analysis of dissolution data of optimized formula indicated the best fitting with Peppas-Korsmeyer model and the drug release kinetics was fickian diffusion. In conclusion, binary SD prepared by both PM and SE technique using POL188 could be considered as a simple, efficient method to prepare ATV solid dispersions with significant improvement in the dissolution rate.