Coadministration has not been studied but should be avoided. Paclitaxel is primarily metabolized by CYP2C8 and to a lesser extent 3A4. Darunavir/cobicistat could potentially increase paclitaxel exposure (inhibition of CYP3A4) and thereby increase the risk of severe neutropenia. Avoid coadministration or consider switching to a non-CYP inhibiting antiretroviral regimen. If coadministration is unavoidable reduce dose of paclitaxel and monitor closely for paclitaxel induced toxicity.