Drug Interaction Report

MONITOR: Tricyclic antidepressants may counteract the anticonvulsive effects of barbiturates by lowering the seizure threshold. Barbiturates may decrease the serum levels and effects of tricyclic antidepressants by induction of hepatic metabolism. In addition, the respiratory-depressant effects of both agents may be increased due to additive pharmacologic effects.

MANAGEMENT: If the barbiturate is being taken for a seizure disorder, patients should be closely monitored for loss of seizure control. Dose adjustments may be required. Monitoring for clinical evidence of additive toxicity and for clinical and/or laboratory evidence of reduced antidepressant effect is also advisable.

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.