Coadministration with Genvoya has not been studied. Elvitegravir plasma concentrations are lower with antacids due to local complexation in the gastrointestinal tract and not to changes in gastric pH. The European SPC recommends to separate Genvoya and antacid administration by at least 4 hours, whereas the US Prescribing Information recommends at least 2 hours separation. Simultaneous administration of a magnesium/aluminium-containing antacid and elvitegravir/ritonavir decreased elvitegravir AUC, Cmax and Cmin by 45%, 47% and 41%, respectively. Separating the doses by 2 hours decreased elvitegravir exposure by 10-20%, whereas separating the doses by 4 hours did not affect elvitegravir exposure. Coadministration with antacids containing calcium carbonate has not been studied. Emtricitabine and tenofovir alafenamide do not interact with antacids.