 Of the five anti-HIV drug classes, four were recommended as first-line regimens for patients who have never received anti-HIV treatment before treatment naive: nucleoside reverse transcriptase inhibitors NRTIs, non-nucleoside reverse transcriptase inhibitors NNRTIs, Integrase Inhibitors INIs and protease inhibitors PIs. The U.S. Department of Health and Human Services HHS guidelines recommend that treatment-naive HIV infected patients be treated with a triple drug regimen that includes 2 NRTIs 1 NNRTI, 2 NRTIs INI, or 2 NRTIs 1 PI as their initial treatment regimen. 