Drug Interaction Report

MONITOR: Several case reports suggest that primidone absorption may be decreased or delayed when acetazolamide is coadministered. Plasma levels of primidone and its two metabolites may be decreased, as may seizure control.

MANAGEMENT: Patients should be monitored for loss of seizure control. If an interaction is suspected or observed, it may be necessary to discontinue acetazolamide, to implement alternative antiseizure therapy, or to do both.

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.