Renal N-oxidation of meperidine by the perfused kidney of the rat.

Isolated perfused kidneys of rats were used to determined renal metabolism of meperidine and its relation to meperidine excretion. Starting perfusate concentrations of meperidine were 18.4 and 190 micrograms/ml, and resulted in respective nonsaturation and saturation kinetics for removal of meperidine. Disposition of 14C-meperidine was followed and supplemented with measurements of meperidine by gas chromatography. A major renal metabolite was shown to facilitate the renal excretion of meperidine. This metabolite was identified by gas chromatography/mass spectrometry as the N-oxide of meperidine.