Effects of labetalol treatment on the physiological and subjective response to smoked cocaine

Adrenergic receptors mediate some of the physiological and possibly behavio ral effects of cocaine. The purpose of this study was to investigate the ef fect of treatment with a peripherally acting adrenergic blocking drug labet alol on the cardiovascular and subjective response to repeated deliveries o f smoked cocaine. In this double-blind, placebo-controlled, crossover study , 12 cocaine users were treated with a single 100 or 200 mg dose of labetal ol, or placebo in each of three experimental sessions. Starting 2 h after t he medication treatment, subjects received three doses of 0.4 mg/kg smoked cocaine, 30 min apart. Labetalol treatment significantly attenuated the coc aine-induced increases in heart rate and systolic blood pressure. This effe ct df labetalol on the cardiovascular response did not decrease with repeat ed cocaine deliveries. The subjective response to smoked cocaine deliveries was not affected by labetalol treatment. These results suggest that labeta lol effectively attenueates the systolic blood pressure and heart rate incr eases induced by repeated doses of smoked cocaine, but does not alter subje ctive effects. (C) 2000 Elsevier Science Inc.