ABSTRACT
We have developed a gas-liquid chromatographic analysis for measuring plasma alphaprodine. The analysis is sufficiently sensitive for studying therapeutic-dose pharmacokinetics in man. Single intravenous bolus injections of either alphaprodine or meperidine were given to volunteer subjects. Plasma concentration data were fitted to a biexpoential equation and pharmacokinetic parameters were calculated. Consistent with alphaprodine's shorter clinical duration compared to meperidine, we found that plasma levels of alphaprodine decline at a more rapid rate. Plasma clearances for the two narcotics are nearly identical (1.04 l./kg/min for alphaprodine and 1.01 l./kg/min for meperidine). The apparent volume of distribution for alphaprodine is smaller than for meperidine (1.90 l./kg for alphaprodine and 3.37 l./kg for meperidine).
Subject(s)
Alphaprodine/metabolism , Meperidine/metabolism , Adult , Alphaprodine/blood , Female , Humans , Kinetics , Male , Meperidine/bloodABSTRACT
We studied the interaction of meperidine and halothane in 24 unmedicated, spontaneously breathing dogs. Intramuscular (i.m.) injections of meperidine, 2.75 mg/kg, 5.5 mg/kg and 11.0 mg/kg reduced the minimal alveolar concentration (MAC) of halothane required for anaesthesia. The magnitude and duration of MAC depression were dose related. Plasma meperidine concentrations following an i.m. injection of 2.75 mg/kg were lower in the awake, unsedated dogs than in the dogs anaesthetized with halothane.