Determination of Nimesulide in Plasma by HPLC with Deproteinization and Its Application to Bioavailability

OBJECTIVE To develop an HPLC-UV method for the determination of nimesulide in plasma and evaluate the bioequivalence of nimesulide capsules.METHODS After being alkalinized,nimesulide was separated on a COSMOSIL C_(18)column (4.6 mm×250 mm,5μm)with acetonitrile-15 mmol·L~(-1)KH_2PO_4 as mobile phase at a flow rate of 1.0 mL·min~(-1).The detection wavelength was at 404 nm.In a randomized crossover design,18 healthy male volunteers were given nimesulide capsules T(test drug) or capsules R(reference drug).The plasma samples were obtained and were determined by the developed HPLC method,and the pharmacokinetics and bioavailability were studied.RESULTS The calibration curve of nimesulide were liner over the range of 0.05 -6.0 mg·L~(-1),and the limit of quantity was 0.05 mg·L~(-1).The methodology recoveries were in the range of 96.8%-103.6%. Inter-day and intra-day RSDs were less than 13.4% and 9.9%,respectively.Pharmacokinetic parameters after a single dose of nimesulide capsules T and R were as following:ρ_(max)were(5.7±1.5)and(5.4±1.4)mg·L~(-1);t_(max)were(3.4±0.5)and(3.4±0.5)h;AUC_(0→24)were(41.4±12.5)and(40.3±15.7)mg·h·L~(-1);AUC_(0→∞)were(42.9±13.2)and(41.5±10.8)mg·h·L~(-1);t_(1/2)were(4.1±1.6)and(4.1±1.5)h.CONCLUSION The method is simple,sensitive and rapid for nimesulide determination.The results of ANOVA and two one-side test analysis showed that there were no significant differences between the pharmacokinetie parameters of the two formulations.The two formulations were bioequivalent.