elvitegravir + ritonavir

Elvitegravir + ritonavir is a combination of two antiretroviral agents used in the treatment of HIV-1 infection, particularly in patients with antiretroviral treatment experience. **Elvitegravir** is an HIV-1 integrase strand transfer inhibitor (INSTI) that works by inhibiting the integrase enzyme, thus preventing integration of viral DNA into the host genome and blocking viral replication. **Ritonavir** is a protease inhibitor that, in this setting, is used primarily as a pharmacokinetic enhancer ("booster") to increase plasma concentrations of elvitegravir by inhibiting cytochrome P450 3A-mediated metabolism of elvitegravir. The combination is commonly coadministered with other antiretrovirals. This regimen is not marketed as a fixed-dose branded product but is used in practice where elvitegravir requires boosting, e.g., when not using the fixed-dose products containing cobicistat.