There has been significant concern over the use of non-PI-containing drug combinations in people with high viral loads (i.e., over 100,000 copies). This is based on some data that compared use of either nevirapine (NVP) plus two NRTIs, and use of abacavir (Ziagen) plus 3TC (Epivir) plus zidovudine (AZT, Retrovir). Compared to PI-containing regimens, both of these combinations had less-favorable rates of virologic suppression in people with high viral loads. However, in a large trial (DuPont 006) of efavirenz (Sustiva), there was no difference in the performance of the efavirenz versus the PI-containing regimens for this group of people.

A study conducted in South Africa, Argentina, Europe and the U.S. looked at the efficacy of the HAART combination of the NNRTI nevirapine (NVP, Viramune), plus AZT (zidovudine, Retrovir) and 3TC (Epivir). At 12 months, 42% (of 79 participants) had HIV RNA viral loads below 50 copies. The results were similar for people starting with baseline viral loads above or below 100,000 copies.

Another study evaluated multiple trials of the efficacy of NVP-containing regimens in people with viral loads over 100,000 copies. After 12 months, 71 of 93 (76%) of people with baseline viral loads under 100,000 copies and 47 of 64 (73%) with baseline viral loads over 100,000 copies had viral loads under 400 copies (on-treatment analysis). This meta-analysis demonstrated that NVP-based therapy appears to be both effective and durable in patients with high as well as low viral loads.