Influence of labetalol on cocaine-induced coronary vasoconstriction in humans.
OBJECTIVE
Although labetalol is sometimes given to patients with cocaine-associated chest pain, its influence on cocaine-induced coronary vasoconstriction is unknown.


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).


CONCLUSIONS
Labetalol reverses the cocaine-induced rise in mean arterial pressure, but does not alleviate cocaine-induced coronary vasoconstriction.
Department of Internal Medicine (Cardiovascular Division), University of Texas Southwestern Medical Center, Dallas 75235.
J D
JD
Boehrer
D J
DJ
Moliterno
J E
JE
Willard
L D
LD
Hillis
R A
RA
Lange
D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D000787:Angina Pectoris / Q000139:chemically induced / Q000188:drug therapy*; D003042:Cocaine / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007741:Labetalol / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged
D003042:Cocaine; D007741:Labetalol