Efavirenz and Valproic acid interaction
Efavirenz and Valproic acid: both prescribing labels describe an interaction that usually calls for monitoring, a dose change, or spacing the doses.
Usually manageable with monitoring or a dose change. Tell your pharmacist you take both.
What the FDA labels say
From the Valproic acid label · effective 2024-05-02
Hepatic enzyme-inducing drugs (e.g., phenytoin, carbamazepine, phenobarbital, primidone, rifampin) can increase valproate clearance, while enzyme inhibitors (e.g., felbamate) can decrease valproate clearance.
Therefore increased monitoring of valproate and concomitant drug concentrations and dosage adjustment are indicated whenever enzyme-inducing or inhibiting drugs are introduced or withdrawn (7.1)
Because of these changes in valproate clearance, monitoring of valproate and concomitant drug concentrations should be increased whenever enzyme inducing drugs are introduced or withdrawn.
Additionally, the relevance of these in vitro findings is uncertain for patients receiving maximally suppressive antiretroviral therapy.
From the Efavirenz label · effective 2024-03-31
Patients who are receiving concomitant anticonvulsant medications primarily metabolized by the liver, such as phenytoin and phenobarbital, may require periodic monitoring of plasma levels [see Drug Interactions ( 7.1 ) ] .
Anticonvulsants:Carbamazepine PhenytoinPhenobarbital ↓ carbamazepine * ↓ efavirenz * ↓ anticonvulsant ↓ efavirenz There are insufficient data to make a dose recommendation for efavirenz.
Potential for reduction in anticonvulsant and/or efavirenz plasma levels; periodic monitoring of anticonvulsant plasma levels should be conducted.
Alternative anticonvulsant treatment should be used.
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.