PRETREATMENT WITH ISRADIPINE, A CALCIUM-CHANNEL BLOCKER, DOES NOT ATTENUATE THE ACUTE BEHAVIORAL-EFFECTS OF ETHANOL IN HUMANS

The acute subject-rated, performance-impairing, and physiological effe cts of ethanol (0, 0.5, and 1 g/kg) were examined after pretreatment w ith isradipine (0, 5, and 10 mg) in nine healthy volunteers. Volunteer s received 1 of the 9 ethanol-isradipine combinations during each of n ine experimental sessions. Ethanol alone produced prototypical subject -rated drug effects (e.g., increased ratings of ''Drunk,'' ''Good effe cts,'' and ''Like drug'') and impaired performance. Isradipine alone a lso produced significant subject-rated drug effects (e.g., increased r atings of ''Drug effect,'' ''Bad effects,'' ''High,'' and ''Stimulated ''), but did not impair performance. Isradipine pretreatment generally did not significantly alter the subject-rated or performance-impairin g effects of ethanol, Isradipine alone, but not ethanol alone, signifi cantly decreased systolic and diastolic blood pressure. The ethanol-is radipine combinations generally produced significantly greater decreas es in blood pressure than were observed with isradipine alone. Breath- alcohol levels were significantly lower after isradipine pretreatment, which suggests isradipine altered the bioavailability of ethanol, The present findings extend previous studies with humans that examined th e behavioral effects of ethanol after pretreatment with other calcium- channel blockers, including nifedipine, nimodipine, and verapamil. Whe reas the available studies suggest that calcium-channel blockers would not be useful pharmacological adjuncts in the management of ethanol a buse, more research is needed. Future studies should use self-administ ration and drug discrimination procedures adapted for use with humans to determine if calcium-channel blockers can attenuate any of the beha vioral effects of ethanol.