ritonavir

Meaning of ritonavir: Ritonavir is a protease-blocking HIV medication now used mainly at low doses to boost blood levels of other antivirals rather than as a standalone treatment.

Definition of ritonavir

Ritonavir is a medication that blocks a viral enzyme called protease, which HIV needs to produce new, infectious copies of itself. It belongs to a class of medications called protease inhibitors, developed originally as a direct treatment for HIV infection.

At the higher doses used when first developed, ritonavir served as a standalone antiviral, but it strongly inhibits an enzyme in the liver that breaks down many other medications, including other protease inhibitors. This effect is now used deliberately, and ritonavir is most often given today in low, boosting doses alongside another antiviral drug, raising that drug's blood level and allowing it to work effectively at a lower dose of its own.

Because of this same liver enzyme blocking effect, ritonavir has also been paired with an antiviral medication used against certain other viral infections, since boosting blood levels through the same mechanism can improve that medication's effectiveness. Ritonavir requires attention to other medications a person is taking, since its enzyme blocking effect can significantly raise or lower the levels of many unrelated drugs.