Micronisation of simvastatin by the supercritical antisolvent technique: in vitro-in vivo evaluation.

Micronisation of simvastatin dissolved in acetone, dimethyl sulfoxide and ethanol with supercritical carbon dioxide as antisolvent was successfully performed using a supercritical antisolvent technique. The effect of a few process parameters such as precipitation temperature, the pressure and solute concentration in the liquid solution has been studied to evaluate their influence on morphology and size of particles. The micronised simvastatin were evaluated for drug content, particle size analysis and in vitro dissolution profiles. Fourier transform infrared spectroscopy, differential scanning calorimetry and PXRD patterns was used to study the possible changes after micronisation of simvastatin. The dissolution rate was increased after micronised compared with pure simvastatin in distilled water, pH 1.2 buffer and pH 7.0 buffer. In vivo performance of the optimised formulation was evaluated in rats using pharmacodynamic marker parameters like serum total cholesterol (CH) and triglycerides (TG) for 21 days. Pharmacodynamic studies of micronised simvastatin revealed improved reduction in CH and TG values as compared with pure simvastatin indicating improved bioavailability. In vivo pharmacokinetics in rats showed an increase in bioavailability of micronised simvastatin (3.14 times) compared with plain simvastatin.