Mefloquine and Primidone interaction
Mefloquine and Primidone: the Mefloquine prescribing label describes 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 Mefloquine (Mefloquine Hydrochloride) label · effective 2025-04-03
Anticonvulsants In patients taking an anticonvulsant (e.g., valproic acid, carbamazepine, phenobarbital or phenytoin), the concomitant use of mefloquine may reduce seizure control by lowering the plasma levels of the anticonvulsant.
Rifampin (Potent Inducer of CYP3A4) Coadministration of a single 500 mg oral dose of mefloquine and 600 mg of rifampin once daily for 7 days in 7 healthy Thai volunteers resulted in a decrease in the mean C max and AUC of mefloquine by 19% and 68%, respectively, and a decrease in the mean elimination half-life of mefloquine from 305 hours to 113 hours.
Similarly, inducers of CYP3A4 may modify the pharmacokinetics/metabolism of mefloquine, leading to a decrease in mefloquine plasma concentrations and potential reduction in efficacy of mefloquine hydrochloride tablets.
Therefore, mefloquine hydrochloride tablets should also be used with caution when administered concomitantly with CYP3A4 inducers.
Inhibitors and Inducers of CYP3A4 Mefloquine does not inhibit or induce the CYP 450 enzyme system.
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.