Comparative in vivo study of pure drug and fast dissolving tablets of Simvastatin

The objective of this study was to investigate differences in the pharmacokinetic patterns between pure drug and an optimized  formulation of fast dissolving tablets  of Simvastatin. The formulations were administered to 2 groups of white New Zealand rabbits (n=6) following cross over design pattern and the plasma levels were measured using LC-MS/MS method. Pharmacokinetic parameters were determined for each formulation. The comparison of the plasma time curves of the dosage forms showed that each dosage form caused significant differences in the drug plasma levels.  The highest mean Cmax value was observed for optimized fast dissolving tablets (68.33 ± 0.42ng/ml) compared to  pure drug (27.72 ± 0.31ng/ml). The mean time taken to peak plasma concentration for (Tmax) following administration of pure drug  was  11.53 ± 0.011hours, while it was 6.09 ± 0.072 hour following administration of selected optimized fast dissolving tablets.The elimination rate constant (Kel) for pure drug and optimized fast dissolving tablets were found to be 0.58 ± 0.012h-1and 0.53 ± 0.014 h-1 respectively.  The absorption rate constant (Ka) for pure drug and optimized fast dissolving tablets were found to be 1.68 ± 0.01h-1and 5.53 ± 0.02h-1 respectively. The AUC0-αvalues observed with optimized fast dissolving tablets686.1.±2.07 nghr/ml in compared to pure drug values 191 ± 1.43 nghr/ml. Thus, the results of pharmacokinetic studies indicated rapid and higher oral absorption of Simvastatin when administered as its fast dissolving tablets. Both Ka and AUC were markedly increased by fast dissolving tablets. Keywords: LC-MS/MS, Simvastatin, fast dissolving, In-vivo studies, pharmacokinetic parameters