Pharmacokinetics of Pirazolac - a New Anti-Inflammatory Drug - in Human Volunteers II. Dose Linearity of Plasma Levels and Excretion.

The concentration-time course of pirazolac in plasma and its urinary excretion were investigated in 6 young volunteers (3 males, 3 females) after oral administration of 50, 150, 300, 450, and 600 mg pirazolac as a crystalline suspension at weekly intervals. Only unchanged pirazolac was detected in the plasma. Maximum plasma levels and areas under the plasma level curve increased linearly with the dose. All other pharmacokinetic parameters such as tmax (3 h), oral clearance CL (0.3ml/min/kg) and terminal plasma half life t1/2 (16-18 h) were independent of the dose. A total of 65 % of the dose was renally excreted within 72 hours mainly as pirazolac glucuronide.