Nevirapine (NVP) itself is an inhibitor of only CYP3A4 at concentrations that are well above those of therapeutic relevance (Ki = 270 mM). [1] Nevirapine is a non-nucleoside RT inhibitor with a well-characterized inhibitory activity on RT enzymes of retroviral origin. Nevirapine is also an effective inhibitor of the endogenous RT in murine and human cell lines. Nevirapine exposure rescues the differentiation block present in acute myeloid leukemia (AML) cell lines and primary blasts from two AML patients, as indicated by morphological, functional and immunophenotypic assays. [2] Nevirapine, a dipyridodiazepinone, is a highly specific inhibitor of HIV-1 reverse transcriptase (RT) which exhibits an IC50 = 84 nM in enzyme assays and IC50 = 40nM against HIV-1 replication in cell culture. [3] Nevirapine alters the cleavage specificity of the RNase H, resulting Nevirapine-induced stimulation of RNase H activity beyond the increase expected from the change in cleavage specificity. [