Coadministration with progesterone as hormone replacement therapy (HRT) has not been studied. Progesterone is metabolized by CYP3A4 and coadministration is predicted to increase progesterone exposure. The clinical significance of this increase in terms of overall risk of deep vein thrombosis, pulmonary embolism, stroke and myocardial infarction in postmenopausal women receiving substitution hormones in unknown. In addition, exposure of estradiol/estrogens administered as part of HRT may also increase. The use of progesterone in combination with estradiol/estrogens should be used at the lowest effective dose and for the shortest duration consistent with treatment goals and risks for individual women. Postmenopausal women should be re-evaluated periodically as clinically appropriate to determine if treatment is still necessary.

Coadministration has not been studied. Zinc is poorly absorbed from the gastro-intestinal tract. It is widely distributed throughout the body and is excreted in the faeces with traces appearing in the urine. Coadministration may decrease elvitegravir concentrations due to chelation with the polyvalent zinc cations. The European SPC recommends to separate Genvoya and administration of products containing polyvalent cations (such as zinc) by at least 4 hours, whereas the US Prescribing Information recommends at least 2 hours separation.

Coadministration has not been studied. Dutasteride is mainly metabolized by CYP3A4 and elvitegravir/cobicistat could potentially increase dutasteride concentrations. A reduction of dutasteride dosing frequency can be considered if side effects are noted. Emtricitabine and tenofovir alafenamide do not interact with dutasteride metabolism.

Coadministration with estradiol as hormone replacement therapy (HRT) has not been studied. Estradiol is metabolized by CYP3A4, CYP1A2 and is glucuronidated. Contrary to ritonavir, cobicistat does not induce CYP1A2 and glucuronidation and therefore coadministration is predicted to increase estradiol exposure due to inhibition of CYP3A4. The clinical significance of this increase in terms of overall risk of deep vein thrombosis, pulmonary embolism, stroke and myocardial infarction in postmenopausal women receiving substitution hormones in unknown. The use of estradiol alone or in combination with a progestogen should be used at the lowest effective dose and for the shortest duration consistent with treatment goals and risks for individual women. Postmenopausal women should be reevaluated periodically as clinically appropriate to determine if treatment is still necessary. Emtricitabine and tenofovir alafenamide do not interact with this metabolic pathway.

Elvitegravir binds to divalent cations such as magnesium, iron or calcium and forms a complex at the level of the gastro-intestinal tract which results in less elvitegravir being absorbed. Divalent cations can be found in multivitamins. As the effect of cationic complexation cannot be excluded, it is recommended to separate the administration of elvitegravir/cobicistat and multivitamin preparations by at least 4 hours. Significant interactions are not expected with emtricitabine and tenofovir alafenamide.