zovirax and Cerebyx Interactions

Interactions between zovirax(acyclovir) and Cerebyx (fosphenytoin)

acyclovir and fosphenytoin (Moderate Drug-Drug)

MONITOR: A case report suggests that plasma phenytoin concentrations may be decreased in the presence of acyclovir. Seizure activity may increase. The mechanism is unknown. A similar interaction may theoretically occur with other hydantoins.

MANAGEMENT: The clinician should consider closer clinical and laboratory monitoring if acyclovir therapy is started or stopped in the presence of phenytoin. The dose of phenytoin should be adjusted as clinically indicated. Patients should be advised to report loss of seizure control.