A pharmacokinetic study of nimesulide in healthy volunteers: Correlation between in vitro dissolution and in vivo absorption

Nimesulide is a non-steroid anti-inflammatory drug (NSAID) used for the treatment of inflammation and pain. Twelve healthy volunteers were recruited for this study to evaluate the bioequivalence of two nimesulide formulations and to further understand the effects of in vitro dissolution on in vivo absorption. After oral administration of 100 mg of nimesulide, maximal concentrations of 4-6 μg/mL were reached after 2-3 hours. A smaller C_max and longer T_max was observed in formulation N, but no difference in t_1/2 was found between the two formulations. In addition, a 17 % reduction in AUC was observed for formulation N, indicating that the extent and rate of absorption of nimesulide were not equivalent between two formulations. The results from in vitro dissolution tests showed that 80 % of nimesulide was released in 20 minutes from formulation A, while only 60 % was released in 3 hours from formulation N. This study suggests that the differences in dissolution can account for differences in absorption of nimesulide in vivo.