Abbott laboratories pharmaceutical products div, Abbott laboratories • Ritonavir is indicated in combination with other antiretroviral agents for the treatment of HIV-1 infection. In the US, Europe, and Canada, ritonavir, in combination with nirmatrelvir, is indicated for the treatment of mild-to-moderate coronavirus disease 2019 (COVID-19) in adults who are at high risk for progression to severe COVID-19, including hospitalization or death. In Europe, this therapeutic indication is approved under conditional marketing authorization.
Ritonavir is an HIV protease inhibitor used in combination with other antivirals in the treatment of HIV infection.
Ritonavic inhibits the HIV viral proteinase enzyme that normally cleaves the structural and replicative proteins that arise from major HIV genes, such as gag and pol. Gag encodes proteins involved in the core and the nucleocapsid, while pol encodes the the HIV reverse transcriptase, ribonuclease H, integrase, and protease . The pol-encoded proteins are initially translated in the form of a larger precursoe polypeptide, gag-pol, and needs to be cleaved by HIV protease to form other complement proteins . Ritonavir prevents the cleavage of the gag-pol polyprotein, which results in noninfectious, immature viral particles. Ritonavir is a potent inhibitor of cytochrome P450 CYP3A4 isoenzyme present both in the intestinal tract and liver . It is a type II ligand that perfectly fits into the CYP3A4 active site cavity and irreversibly binds to the heme iron via the thiazole nitrogen, which decreases the redox potential of the protein and precludes its reduction with the redox partner, cytochrome P450 reductase . Ritonavir may also play a role in limiting cellular transport and efflux of other protease inhibitors via the P-glycoprotein and MRP efflux channels .
