Effects of bromocriptine pretreatment on subjective and physiological responses to i.v. cocaine

We studied the effect of pretreatment with single doses of bromocriptine on the pattern of subjective and physiologic responses to single doses of intravenous (IV) cocaine. Placebo, bromocriptine 2.5 mg and, in five subjects only, 5 mg were administered orally 120 minutes before a dose of placebo or cocaine 40 mg IV to 9 male cocaine-using volunteers. Bromocriptine pretreatment diminished blood pressure generally, including cocaine-induced blood pressure increases, and augmented the heart rate after cocaine. It caused virtually no change in either augmentation or diminution of subjective responses including "rush" and "good feeling" scores, and scores for the MBG of the Addiction Research Center Inventory (ARCI), all measures of euphoria. However, a trend for the scores for the item "Would a dose of drug (cocaine) make you feel better?," suggested that bromocriptine may decrease the urge to use cocaine that was evoked by cocaine itself. However, this decreased desire was associated with a trend toward an increase in dysphoria as measured on the LSD scale of ARCI. These data support the view that euphoria and some forms of craving may be pharmacologically separable. We found no potentially toxic interactions of bromocriptine with cocaine in these single dose experiments.