Dose-dependent pharmacokinetics of metabolites of dipyrone in saliva.

Metabolites of dipyrone have been determined in the saliva of 18 volunteers following the oral intake of 0.5 g, 1.0 g, 1.5 g, 2.0 g and 2.5 g dipyrone. High concentrations were measured for N-methyl-aminoantipyrine (MAA), the other analgetic active metabolite, 4-aminoantipyrine was found in minor quantities only. N-formyl-antipyrine was not present in the saliva of some volunteers after low doses but could be determined following the intake of doses from 1.5 g - 2.5 g in saliva of all volunteers. N-acetyl-antipyrine appears late in saliva, acetylation rates varied greatly interindividually. Concentrations of the metabolites in saliva mimic the respective non-protein bound fraction in plasma found by other authors.