The metabolic disposition of dezocine in rhesus monkeys and female rats given 14C-dezocine intragastrically.

The metabolic disposition of 14C-dezocine has been investigated in male rhesus monkeys and female rats given intragastric 1- and 5- mg/kg doses, respectively. In both species the dose appeared to be rapidly and extensively absorbed. Concentrations of radioactivity were detected in monkey plasma 15 min after drug administration (the earliest sampling time) and reached a peak between 0.5 and 2 hr, whereas in the rat, high concentrations of radioactivity were detected in plasma and most tissues at 15 min. Biliary secretion was extensive in the monkey, but in the monkey as well as in the rat, the ultimate excretion of the radioactive dose was primarily through renal elimination. Tissue uptake of unconjugated drug was extensive in both species, and concentrations of drug in brain were substantially higher than those in plasma. Metabolism was mainly by glucuronidation in both species and also by sulfate formation in the female rat. Two minor imine metabolites produced by N-oxidation were indicated after a comparison with synthetic standards.