Phase I/II Evaluation of Nevirapine Alone and in Combination with Zidovudine for Infection with Human Immunodeficiency VirusCheeseman Sarah H.; Havlir, Diane; McLaughlin, Margaret M.; Greenough, Thomas C.; Sullivan, John L.; Hall, David; Hattox, Susan E.; Spector, Stephen A.; Stein, Daniel S.; Myers, Maureen; Richman, Douglas D.JAIDS Journal of Acquired Immune Deficiency Syndromes: February 1995 ORIGINAL ARTICLE: PDF Only Abstract In these Phase I/II open-label clinical trials, 62 persons with human immunodeficiency virus type 1 (HIV-1) infection and CD4+ cell counts ≤400/mm3 received nevirapine at doses of 12.5, 50, and 200 mg/day, alone or in combination with zidovudine, 200 mg q8h. Nevirapine was well tolerated in the doses tested. Mean steady-state trough levels were 0.23, 1.1, and 1.9 μg/ml for the 12.5, 50, and 200 mg/day doses, respectively. Early suppression of p24 antigen levels and increase in CD4+ cell count were reversed following rapid emergence of virus less susceptible to nevirapine. Resistant strains were isolated from all participants by 8 weeks. Nevertheless, reduction of p24 arifigen levels to ≤50% of baseline values persisted for 12 weeks or more in four of seven persons who received 200 mg nevirapine/day in combination with zidovudine: these individuals had been antigenemic on long-term zidovudine therapy. This study demonstrates a direct relationship between drug resistance and effects on surrogate markers in HIV-1 infection. © Lippincott-Raven Publishers.