BIOTRANSFORMATION OF PETHIDINE - A COMPARATIVE-STUDY OF 24 H URINE IN3 ETHNIC-GROUPS

219 surgical patients of either Caucasian, Chinese or Nepalese origin were given pethidine 1 mg/kg by intramuscular injection as pre-operati ve medication. Urine was collected for 24 h and analysed for pethidine , pethidinic acid, pethidinic acid conjugates, norpethidine, norpethid inic acid, and norpethidinic acid conjugates. The mean proportion of t he percentage of metabolites attributable to oxidative demethylation, hydrolysis and conjugation was almost identical in each ethnic group ( P > 0.2). It was concluded that there were no differences in the metab olic variability of the biotransformation of pethidine in Asians and C aucasians in whom the urine pH had not been acidified.