Cocaine-induced rausch: overt behaviour and plasma concentrations in rhesus monkeys

This study was designed to characterize the cocaine-induced rausch or hyperarousal syndrome in rhesus monkeys. This syndrome mimics the stage observed in human abusers bingeing on cocaine and is considered crucial in the progression from recreational use to compulsive abuse. However, little research has focused on this important aspect of cocaine use. Cocaine was administered i.v. at doses of 0.0, 0.5, 1.0 and 2.0 mg/kg. Plasma concentrations were determined by gas chromatograph mass spectrometry (GC/MS) using deuterated internal standards d3 cocaine and d3 benzoylecgonine (BE). Mean plasma concentrations of cocaine, were on samples collected 1 min after infusion, 46 +/- 31, 88 +/- 15 and 275 +/- 116 mg/microliters in the 0.5, 1.0 and 2.0 mg/kg dose groups, respectively. There were no detectable concentrations of BE in any of the specimens nor was cocaine detected in the saline controls. Analysis of the behavioural data revealed that the 0.5 and 1.0 mg/kg results were intermediate between the results obtained at doses of 0.0 and 2.0 mg/kg and that the 1.0 mg/kg dose produced a higher response than the 0.5 mg/kg dose up to the 12 min. Regarding individual behavioural signs, those designated escape attempts, checking, feinting, restlessness, searching, vocalizing, chewing, crouching and wide-eyed were noted most frequently. The results showed dose-response relationships for both plasma concentrations of cocaine and for the total number of overt behavioural signs. The plasma concentrations were in the range reported for human cocaine abusers.