– HIV-1 protease-IN-4 (Compound II-22), a potent inhibitor of the HIV-1 protease, acts as a prodrug for atazanavir and significantly enhances its bioavailability in rat plasma, achieving a 5-fold increase in the area under the curve (AUC) and a 67-fold increase in concentration at 24 hours (C24) compared to oral administration of atazanavir alone [1].