Protease inhibitors

Saquinavir, ritonavir and indinavir are well-known protease inhibitors in the treatment of HIV-infection. These drugs inhibit the enzymes (proteases) that split viral proteins. In this way the formation of essential polypeptides and enzymes is decreased. This leads to production of immature and non-functional new viruses, which are not able to infect new cells.

All protease inhibitors cause gastrointestinal side effects. Moreover, long-term therapy can be implicated in lipodystrophy and dyslipidemia. All protease inhibitors are inhibitors of the CYP3A4 system and thus interact with numerous other drugs.


Saquinavir inhibits HIV replication by blocking uncoating of the virus during penetration.


Combination of protease inhibitors and NRTI drugs produces additive antiviral effects and reduces the incidence of resistance. 


Indinavir is an irreversible inhibitor of the HIV protease.