Coadministration is expected to decrease concentrations of cobicistat but the effect on darunavir is unknown. Consider alternative anticonvulsant or antiretroviral therapy to avoid potential changes in exposures. If co-administration is necessary, monitor for lack or loss of virologic response.

The drug-drug interactions between antiretrovirals and carbamazepine or oxcarbazepine were evaluated in a clinical setting using therapeutic drug monitoring (TDM) trough concentrations collected from HIV+ patients treated concomitantly with carbamazepine or oxcarbazepine and antiretrovirals for at least 3 months. HIV-infected patients not concomitantly treated with antiepileptic drugs and who underwent TDM for antiretrovirals in the previous 2 years were considered as controls. Eleven HIV-positive patients prescribed carbamazepine (n=7) or oxcarbazepine (n=4) were identified. All the TDM evaluations for carbamazepine and oxcarbazepine were within the therapeutic ranges. TDM results of darunavir measured in these patients were comparable with values usually measured in the control group.