PHARMACOKINETICS OF TOLFENAMIC ACID IN PEDIATRIC-PATIENTS AFTER SINGLE ORAL DOSE

The pharmacokinetics of tolfenamic acid, a non-steroidal anti-inflamma tory drug, were determined following administration of a 1 mg/kg singl e oral dose of tolfenamic acid suspension to 6 feverish children. Thei r ages were from 2-14 years (mean 7.5 years) and their weights were fr om 12-50 kg (mean 29.2 kg). Tolfenamic acid produced a significant fal l in temperature (about 2 degrees C) compared to the initial value bef ore oral intake of the drug and was well tolerated without adverse eff ects. Blood samples for determination of tolfenamic acid concentration s in plasma were obtained at timed intervals for up to 8 h post-dose. Plasma concentrations of tolfenamic acid were determined using a rever sed phase HPLC method and pertinent pharmacokinetic parameters were es timated by model-independent standard methods and were the following: the mean peak plasma concentration (C-max +/- SEM) was 1.09 +/- 0.44 m u g/ml (range, 0.65 - 1.63 mu g/ml) and the mean time (t(max) +/- SEM) to reach peak plasma concentration was 1.4 +/- 0.4 h (range, 0.5 - 3. 0 h). The mean area under the plasma concentration-time curve (AUC(0-- >infinity) +/- SEM) was 4.61 +/- 0.40 mu g.h/ml (range, 2.74 - 5.98 mu g.h/ml), the mean elimination half-life (t(1/2) +/- SEM) was 2.82 +/- 0.21 h (range, 2.19 - 3.40 h) and the mean apparent total clearance ( CL/F +/- SEM) was 3.83 +/- 0.41 ml/min/kg (range, 2.79 - 6.08 ml/min/k g).