Nevirapine (Viramune) is able to reduce HIV-1 viral load and increase CD4 cell counts in the majority of people when taken in combination with at least two other antiretroviral drugs. Nevirapine is not active against HIV-2.

Nevirapine was licensed after three clinical trials found that the combination of nevirapine, AZT (zidovudine, Retrovir) and ddI (didanosine, Videx) brought about greater decreases in viral load and increases in CD4 cell counts than AZT and ddI taken without nevirapine in patients who had not taken antiretroviral therapy before. The triple combination also led to fewer cases of HIV disease progression^[1][2][3].

Several studies have reported that triple regimens including nevirapine are as effective as protease inhibitor-containing regimens^[4][5][6]. Concerns about the potency of nevirapine in people who begin treatment with high viral load have been dispelled by these studies^[7]. A recent study has also demonstrated that nevirapine is a safe and effective option for patients beginning therapy with a CD4 cell count below 200 cells/mm^3[8].

The latest research suggests that nevirapine-based regimens are not inferior to efavirenz (Sustiva)-based regimens in patients who have not taken anti-HIV therapy before. The 2NN study found no significant difference between efavirenz and once and twice daily nevirapine when taken with d4T (stavudine, Zerit) and 3TC (lamivudine, Epivir) in terms of the percentage of patients with undetectable viral load at week 48, CD4 cell count increases and quality of life. Nevirapine-treated individuals were more likely to develop liver toxicity in this study, although Boehringer Ingelheim has claimed that this difference was driven by unusual findings from one of the study’s 65 centres, which contributed 17% of the study’s patients^[9][10][11].

Switching from a protease inhibitor to either nevirapine or efavirenz also appears to be equivalent in terms of virological response, although lipid levels may improve more after a switch to nevirapine^[12][13]. Patients who have switched from a protease inhibitor to nevirapine have been shown to have a high chance of virological suppression for over three years^[14].

Nevirapine can penetrate into the brain and spinal fluids, where it may have anti-HIV activity^[15].

Nevirapine has also been proposed as a useful drug to prevent HIV infection in people who have been exposed to the virus^[16]. However, some experts have suggested that post-exposure prophylaxis using nevirapine be avoided because the risk of HIV seroconversion is relatively low, while severity of potential side-effects quite great^{[17][18][19][20]}. In 2001, the United States Food and Drug Administration (FDA) recommended avoiding the use of nevirapine as post-exposure prophylaxis after reports of life-threatening side-effects, which may be more severe in HIV-negative people^[21]. For further information on post-exposure prophylaxis including nevirapine, see Drugs for post-exposure prophylaxis.