Drug Interactions between chlorzoxazone and disulfiram

CONTRAINDICATED: Consumption of ethanol during treatment with disulfiram may cause flushing, nausea, blurred vision, dyspnea, tachypnea, tachycardia, and hypotension. Death has been reported. The mechanism is probably related to inhibition of aldehyde dehydrogenase, the enzyme responsible for the oxidation of acetaldehyde to acetyl CoA. Accumulation of acetaldehyde probably results.

MANAGEMENT: Ethanol should be avoided in patients receiving disulfiram.

GENERALLY AVOID: Alcohol may potentiate some of the pharmacologic effects of CNS-active agents such as chlorzoxazone. Use in combination may result in additive central nervous system depression and/or impairment of judgment, thinking, and psychomotor skills. In addition, in one small study, watercress was reported to increase chlorzoxazone peak concentrations, AUC, and half-life. The proposed mechanism is inhibition of CYP450 2E1 metabolism. The clinical significance is unknown.

MANAGEMENT: Patients receiving chlorzoxazone should be advised to avoid or limit consumption of alcohol. Ambulatory patients should be counseled to avoid hazardous activities requiring complete mental alertness and motor coordination until they know how chlorzoxazone affects them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities. Watercress should be avoided if an interaction is suspected; e.g., excess sedation, nausea, or headache occurs.