Drug Interaction Report

MONITOR: Barbiturates may increase the hepatic metabolism of chloramphenicol. Serum chloramphenicol levels and effectiveness may be decreased. Coadministration also may enhance the pharmacologic effect of barbiturates. The proposed mechanism is induction of chloramphenicol metabolism by barbiturates and inhibition of barbiturate metabolism by chloramphenicol.

MANAGEMENT: The effectiveness of chloramphenicol should be monitored, and plasma levels should be checked as clinically appropriate. Dosage should be increased as needed. The patient also should be monitored for barbiturate toxicity.

GENERALLY AVOID: Concurrent acute use of barbiturates and ethanol may result in additive CNS effects, including impaired coordination, sedation, and death. Tolerance of these agents may occur with chronic use. The mechanism is related to inhibition of microsomal enzymes acutely and induction of hepatic microsomal enzymes chronically.

MANAGEMENT: The combination of ethanol and barbiturates should be avoided.