Effect of age on the pharmacokinetics of dipyrone.

The pharmacokinetics of the dipyrone metabolite, 4-methylaminoantipyrine (MAA) was evaluated, following the administration of a single oral dose of dipyrone 1.0 g to 12 young (21-30 years) and 9 elderly (73-90 years) healthy volunteers. Maximal concentration, time to peak and absorption rate of MAA were similar for both groups. The elimination half-life was 2.6 (0.2) h for the young and 4.5 (0.5) h for the elderly subjects. Total clearance of MAA, corrected for lean body mass (LBM), was lower in the elderly than in the young 2.65 vs 3.97 ml.min-1.kg-1 LBM. There was no differences between the groups in the apparent volume of distribution. A good correlation was found between the total body clearance of MAA and the creatinine clearance, which was also reduced in the elderly (r = 0.61).