A potentially significant interaction between efavirenz and phenytoin: a case report and review of the literature.

Article Details

Citation

Robertson SM, Penzak SR, Lane J, Pau AK, Mican JM

A potentially significant interaction between efavirenz and phenytoin: a case report and review of the literature.

Clin Infect Dis. 2005 Jul 15;41(2):e15-8. doi: 10.1086/431208. Epub 2005 Jun 7.

PubMed ID
15983905 [ View in PubMed
]
Abstract

Although it has not been demonstrated yet, phenytoin is expected to reduce efavirenz exposure through coinduction of cytochrome P450 (CYP) 3A4 and CYP2B6. Conversely, efavirenz has been shown in vitro to inhibit the enzymes responsible for phenytoin metabolism, CYP2C9 and CYP2C19. We report a case in which a potential bidirectional drug interaction between phenytoin and efavirenz resulted in lower-than-expected efavirenz concentrations and elevated phenytoin levels. Therapeutic drug monitoring was used in this case to ensure adequate efavirenz exposure.

DrugBank Data that Cites this Article

Drugs
Drug Interactions
DrugsInteraction
Efavirenz
Phenytoin
The serum concentration of Efavirenz can be decreased when it is combined with Phenytoin.
Efavirenz
Fosphenytoin
The serum concentration of Efavirenz can be decreased when it is combined with Fosphenytoin.