Abstract: Objective To study the release rate of niacin for Niacin extended-release and Simvastatin tablets in different media, and analyze their release behavior in vitro. Methods The release of Niacin for self-prepared and imported compound preparation in four different media were determined by UV, the kinetics model and similarity factor(f2 value) were compared. Results Self-made and imported sustained-release tablets in vitro release of nicotinic acid were complied with the Ritger-Peppas equation, the n values of the equation in the four media were from 0.45 to 0.89, indicating that the drug release was caused by the interaction of the skeleton of drug diffusion and dissolution. Comparing with the value of the reference formulation, the f2 value of the self extended-release tablets which were in water, 0.1mol/L HCl, pH 4.5 acetate buffer and pH 6.8 phosphate buffer release medium were 67.59, 80.24, 67.27 and 65.57 respectively, which were greater than 50. Conclusion Niacin release behavior of self-prepared was consistent with the imported extended-release tablets in vitro.

Key words: Niacin, Simvastatin, extended-release tablets, release rate