Drug Interactions between ethionamide and rifampin

GENERALLY AVOID: The concomitant use of protionamide with alcohol may enhance the central nervous system exciting effect of protionamide. The mechanism is not known. Excessive use of alcohol with another thiocarbamide derivative ethionamide, has been reported to precipitate a psychotic reaction. In addition, alcohol tolerance is reported to be reduced during protionamide treatment.

MANAGEMENT: Consumption of alcohol during protionamide treatment should be avoided. The manufacturer of ethionamide also advises that excess alcohol consumption should be avoided during ethionamide therapy (US).

GENERALLY AVOID: Concurrent use of rifampin in patients who ingest alcohol daily may result in an increased incidence of hepatotoxicity. The increase in hepatotoxicity may be due to an additive risk as both alcohol and rifampin are individually associated with this adverse reaction. However, the exact mechanism has not been established.

ADJUST DOSING INTERVAL: Administration with food may reduce oral rifampin absorption, increasing the risk of therapeutic failure or resistance. In a randomized, four-period crossover phase I study of 14 healthy male and female volunteers, the pharmacokinetics of single dose rifampin 600 mg were evaluated under fasting conditions and with a high-fat meal. Researchers observed that administration of rifampin with a high-fat meal reduced rifampin peak plasma concentration (Cmax) by 36%, nearly doubled the time to reach peak plasma concentration (Tmax) but reduced overall exposure (AUC) by only 6%.

MANAGEMENT: The manufacturer of oral forms of rifampin recommends administration on an empty stomach, 30 minutes before or 2 hours after meals. Patients should be encouraged to avoid alcohol or strictly limit their intake. Patients who use alcohol and rifampin concurrently or have a history of alcohol use disorder may require additional monitoring of their liver function during treatment with rifampin.