Coadministration has not been studied. Mirtazapine is metabolised to 8-hydroxymirtazapine by CYP2D6 and CYP1A2, and to N-desmethylmirtazapine mainly by CYP3A4. Darunavir/cobicistat could potentially increase mirtazapine concentration. Monitor side effects and consider dose reduction if needed. Emtricitabine and tenofovir alafenamide do not interact with this metabolic pathway.