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Protease Inhibitors (PIs)

for Veterans and the Public

Protease Inhibitors (PIs)

This group of drugs is the protease (pronounced "pro-tee-ase") inhibitors (PIs).

Once HIV has infected a cell and made copies of itself, it uses an enzyme called protease to process itself correctly so it can be released from the cell to infect other cells. These medicines work by blocking protease.

There are nine PIs, but only a couple of them are used currently (see the Drug Dosing Toolkit for PIs that are not listed here).

  • Atazanavir (brand name: Reyataz®)
  • Darunavir (brand name: Prezista®)
  • Lopinavir (combined with ritonavir in one table; brand name: Kaletra®)

Many PIs are recommended or approved for use only with another drug that "boosts" their effect. One of these boosters is ritonavir (Norvir®), the other is cobicistat (Tybost®) (Pharmacokinetic Enhancers).

There are three fixed-dose combination tablets that include a "booster" plus a PI:

  • Evotaz® (atazanavir + ritonavir)
  • Prezcobix® (darunavir + cobicistat)
  • Kaletra® (lopinavir + ritonavor)