A poster presented at the joint 2008 ICAAC/IDSA meeting in Washington, DC found that it was generally safe to substitute Viramune (nevirapine) for Sustiva (efavirenz) when people were experiencing unacceptable side effects. The study, while small, may help provide options for some people who cannot tolerate Sustiva but wish to avoid using a protease inhibitor (PI).
Use of Viramune, an NNRTI like Sustiva, has been limited mostly due to its uncommon but potentially severe drug reactions. Women with CD4 counts above 250 and men with counts above 400 are generally discouraged from starting a regimen with Viramune due to a higher risk of catastrophic liver damage. Like Sustiva, Viramune has been shown to cause a rash in some people. Unlike Sustiva, it has not been shown to change levels of blood fats.
While Sustiva is widely used and generally well tolerated, some people are unable to tolerate it due to side effects. The most common ones are central nervous system (CNS) effects like dizziness and sleep disturbance as well as rash. Some people with a history of substance dependence find Sustiva's mild CNS effects particularly troubling.
HIV therapy that includes PIs is most commonly given to people who can't tolerate Sustiva. Some people wish to avoid PIs due to their risk of both short- and long-term side effects, including gastrointestinal distress and elevated risk of heart disease.
The study presented looked at people who had taken Sustiva in the ACTG 5095 study, who could not tolerate it due to side effects. Overall, 75 people (55 male and 20 female) switched to Viramune. 85% of people who switched due to CNS effects improved after switching, while 15 of 18 had their rash improve. Six people had rash while taking Viramune, and 14% had liver problems after the switch compared to 6% of those who didn't switch. Most people who switched maintained good control over their HIV.
This study suggests switching to Viramune may be a safe option for some people who cannot tolerate Sustiva. The risk of drug-related liver problems is greater for women and people with high CD4 counts (women >250, men >400) when starting Viramune, so it should be used with extreme caution in these people.