Influence of labetalol on cocaine-induced coronary vasoconstriction in humans

purpose: Although labetalol is sometimes given to patients with cocaine-associated chest pain, its influence on cocaine-induced coronary vasoconstriction is unknown. patients and methods: In 15 patients (7 men, 8 women, aged 40 to 79 years) undergoing catheterization for chest pain, heart rate, mean arterial pressure, and coronary arterial area (by computer-assisted quantitative angiography) were measured (1) at baseline, (2) 15 minutes after intranasal cocaine, 2 mg/kg, then (3) 5 minutes after intravenous saline (n = 6) or labetalol, 0.25 mg/kg (n = 9). results: Of 40 coronary arterial segments analyzed, cocaine induced a 13% ± 10% (mean ± standard deviation) decrease in coronary arterial area in 32. Subsequently, no variable changed after saline administration. Although labetalol reduced mean arterial pressure (117 ± 14 mm Hg after cocaine, 110 ± 11 mm Hg after labetalol; p < 0.05), it induced no change in the coronary arterial area (3.47 ± 1.37 mm² after cocaine, 3.37 ± 1.32 mm² after labetalol; p = NS). conclusion: Labetalol reverses the cocaine-induced rise in mean arterial pressure, but does not alleviate cocaine-induced coronary vasoconstriction.