Disposition of (3H) benzoylnorecgonine (cocaine metabolite) in the rat.

The preparation and disposition of (3H) benzoylnorecgonine, which has potent stimulant activity intracisternally in the rat, has been described. The T1/2 of (3H) benzoylnorecgonine in brain and plasma of rats injected with a 10 mg kg-1 i.v. dose were 3.0, 1.2 h respectively. The ratio of mean peak concentration in brain to that in plasma was 0.03. No metabolites of benzoylnorecgonine were observed in rat brain. The mean percentage of dose excreted in urine and feces in 96 h were 85 and 2.2, respectively, with major excretion (82.5%) occurring within 24 h in urine. Approximately 90% of the radioactivity in urine was due to unmetabolised benzoylnorecgonine and 10% due to an unidentified metabolite. Norecgonine was not detected as a urinary metabolite.