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Possible interaction between acyclovir and antiepileptic treatment
A Parmeggiani1, R Riva, A Posar
1Department of Child Neurology and Psychiatry, University of Bologna, Bologna, Italy.
Insights
Acyclovir may reduce levels of antiepileptic drugs phenytoin and valproic acid, potentially worsening seizure control. This suspected drug interaction requires careful monitoring in patients on both medications.
Area of Science:
- Pharmacology
- Clinical Pharmacy
- Drug Interactions
Background:
- Antiepileptic drugs like phenytoin (PHT) and valproic acid (VPA) are crucial for managing seizure disorders.
- Acyclovir is a widely used antiviral medication.
Observation:
- A clinical case involving a child treated with PHT and VPA is presented.
- The child received a 6-day course of acyclovir therapy.
Findings:
- Concomitant acyclovir administration led to a significant decrease in plasma concentrations of both PHT and VPA.
- These reduced drug levels fell below therapeutic targets, coinciding with clinical and electroencephalographic (EEG) deterioration.
Implications:
- This suspected interaction suggests acyclovir may reduce the oral bioavailability of PHT and VPA.
- Clinicians should consider potential interactions when prescribing acyclovir to patients on PHT or VPA.
- Close monitoring of antiepileptic drug levels and clinical status is recommended during concurrent antiviral treatment.
Abstract:
We report a clinically relevant suspected interaction between acyclovir and the antiepileptic drugs phenytoin (PHT) and valproic acid (VPA). In a child receiving PHT and VPA therapy, a 6-day acyclovir treatment reduced PHT and VPA plasma concentrations to subtherapeutic values. This probably worsened both clinical status and electroencephalographic recordings observed in this patient. We suggest that the interaction occurs at gastrointestinal level with a reduction of PHT and VPA oral bioavailability during antiviral treatment.