Abstract
The effect of viloxazine (150-300 mg daily for 21 days) on plasma phenytoin levels at steady state was examined in 10 epileptic patients stabilised on a fixed phenytoin dosage. After starting viloxazine treatment, plasma phenytoin concentrations increased by 37% on average (range 7-94%) from a mean value of 18.8 micrograms/ml at baseline to a mean value of 25.7 micrograms/ml during the last week of combined therapy. In four patients the rise in plasma phenytoin was associated with the development of signs of phenytoin toxicity. Discontinuation of viloxazine resulted in return of plasma phenytoin towards baseline values and disappearance of the clinical symptoms. The mechanism of interaction probably involves inhibition of phenytoin metabolism by viloxazine. Careful monitoring of plasma phenytoin levels is recommended in patients treated with phenytoin who need to be started on viloxazine therapy.
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Selected References
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- Edwards J. G., Glen-Bott M. Does viloxazine have epileptogenic properties? J Neurol Neurosurg Psychiatry. 1984 Sep;47(9):960–964. doi: 10.1136/jnnp.47.9.960. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Luchins D. J., Oliver A. P., Wyatt R. J. Seizures with antidepressants: an in vitro technique to assess relative risk. Epilepsia. 1984 Feb;25(1):25–32. doi: 10.1111/j.1528-1157.1984.tb04151.x. [DOI] [PubMed] [Google Scholar]
- Meldrum B. S., Anlezark G. M., Adam H. K., Greenwood D. T. Anticonvulsant and proconvulsant properties of viloxazine hydrochloride: pharmacological and pharmacokinetic studies in rodents and the epileptic baboon. Psychopharmacology (Berl) 1982;76(3):212–217. doi: 10.1007/BF00432547. [DOI] [PubMed] [Google Scholar]
- Perucca E. Pharmacokinetic interactions with antiepileptic drugs. Clin Pharmacokinet. 1982 Jan-Feb;7(1):57–84. doi: 10.2165/00003088-198207010-00004. [DOI] [PubMed] [Google Scholar]
- Perucca E., Richens A. Drug interactions with phenytoin. Drugs. 1981 Feb;21(2):120–137. doi: 10.2165/00003495-198121020-00003. [DOI] [PubMed] [Google Scholar]
- Pinder R. M., Brogden R. N., Speight T. M., Avery G. S. Viloxazine: a review of its pharmacological properties and therapeutic efficacy in depressive illness. Drugs. 1977 Jun;13(6):401–421. doi: 10.2165/00003495-197713060-00001. [DOI] [PubMed] [Google Scholar]
- Pisani F., Fazio A., Oteri G., Perucca E., Russo M., Trio R., Pisani B., Di Perri R. Carbamazepine-viloxazine interaction in patients with epilepsy. J Neurol Neurosurg Psychiatry. 1986 Oct;49(10):1142–1145. doi: 10.1136/jnnp.49.10.1142. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Pisani F., Fazio A., Spina E., Artesi C., Pisani B., Russo M., Trio R., Perucca E. Pharmacokinetics of the antidepressant drug viloxazine in normal subjects and in epileptic patients receiving chronic anticonvulsant treatment. Psychopharmacology (Berl) 1986;90(3):295–298. doi: 10.1007/BF00179180. [DOI] [PubMed] [Google Scholar]
- Pisani F., Narbone M. C., Fazio A., Crisafulli P., Primerano G., D'Agostino A. A., Oteri G., Di Perri R. Effect of viloxazine on serum carbamazepine levels in epileptic patients. Epilepsia. 1984 Aug;25(4):482–485. doi: 10.1111/j.1528-1157.1984.tb03447.x. [DOI] [PubMed] [Google Scholar]