Ritonavir hæmmer det hepatiske cytokrom P450 CYP3A, udstrømningspumpen for P- glykoprotein (Pgp) i tarmen og muligvis også cytokrom P450 CYP3A i tarmen.
Ritonavir acts by inhibiting hepatic cytochrome P450 CYP3A, the intestinal P-glycoprotein (Pgp) efflux pump and possibly intestinal cytochrome P450 CYP3A as well.