Coadministration has not been studied. Paroxetine is mainly metabolized by CYP2D6 and 3A4. Elvitegravir/cobicistat could potentially increase paroxetine exposure. However, this interaction is difficult to predict as paroxetine exposure was decreased with some ritonavir-boosted PIs (i.e., fosamprenavir, darunavir) by an unknown mechanism. Careful dosage titration of the antidepressant and monitoring for antidepressant response are recommended. Emtricitabine and tenofovir alafenamide do not interact with this metabolic pathway.