The effects of oral nifedipine pretreatment on subjective and cardiovascular responses to intravenous cocaine infusions were studied in cocaine-using volunteers. Nifedipine, 10 mg or placebo, was administered 20-25 min before placebo, 20 mg, or 40 mg cocaine, using a repeated measures randomized double-blind design. The variables measured were self-reported subjective effects, general behavior rated by two observers, blood pressure and heart rate. Cocaine produced the expected dose-related effects on subjective and cardiovascular measures. Nifedipine pretreatment attenuated some subjective effects of cocaine. Nifedipine directly reduced blood pressure but did not antagonize the effects of cocaine on blood pressure. These findings suggest that dihydropyridine calcium channel modulators may be useful compounds in the clinical management of cocaine users.
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