Pharmacokinetics of diclofenac sodium using a developed HPLC method.

The pharmacokinetics of 2-[(2,6-dichlorophenyl)-amino]phenyl acetic acid (diclofenac sodium) was studied after a single oral dose of 10 mg/kg in rabbits, using a developed HPLC method. The observed serum levels of rabbits were fitted to a one-compartment open model, with first-order absorption and elimination. The mean values of t1/2e, ke, 51/2a, ka and tmax were 1.98 h, 0.3455 h-1, 1.2357 h, 1.2357 h, 0.5653 h-1 and 2.2267 h, respectively. This high-performance liquid chromatographic method for the rapid (about 10 min), sensitive (1 microgram/ml) and specific determination of diclofenac sodium in serum and urine was developed using acetaminophen as the internal standard, a reversed-phase C 18 column, and ethanol: water (1:2) as the mobile phase.