Drug Interactions between disulfiram and Synalgos-DC

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: The concurrent use of aspirin or nonsteroidal anti-inflammatory drugs (NSAIDs) and ethanol may lead to gastrointestinal (GI) blood loss. The mechanism may be due to a combined local effect as well as inhibition of prostaglandins leading to decreased integrity of the GI lining.

MANAGEMENT: Patients should be counseled on this potential interaction and advised to refrain from alcohol consumption while taking aspirin or NSAIDs.

The effect of grapefruit juice on the pharmacologic activity of caffeine is controversial. One report suggests that grapefruit juice increases the effect of caffeine. The proposed mechanism is inhibition of cytochrome P-450 metabolism of caffeine. However, a well-conducted pharmacokinetic/pharmacodynamic study did not demonstrate this effect. The clinical significance of this potential interaction is unknown.

One study has reported that coadministration of caffeine and aspirin lead to a 25% increase in the rate of appearance and 17% increase in maximum concentration of salicylate in the plasma. A significantly higher area under the plasma concentration time curve of salicylate was also reported when both drugs were administered together. The exact mechanism of this interaction has not been specified. Physicians and patients should be aware that coadministration of aspirin and caffeine may lead to higher salicylate levels faster.