HIV Nucleoside Reverse Transcriptase Inhibitors

Currently, 16 antiretroviral drugs are approved for treatment of HIV infection. However, even the best currently available regimens pose challenges with regard to adherence, toxicity, antiviral activity, and resistance. New drug development thus confronts the need for improved convenience and tolerability, reduced toxicity, and improved activity against both wild-type and drug-resistant viruses. Other goals of drug development include improved drug penetration into viral reservoirs (eg, genital tract and central nervous system) and exploitation of additional viral targets with the aims of achieving additive or synergistic effects with drugs from existing classes, reducing or preventing viral resistance, and improving treatment options in cases of drug resistance. Newly available or investigational formulations or doses of existing nucleoside reverse transcriptase inhibitors (nRTIs), nonnucleoside reverse transcriptase inhibitors (NNRTIs), and protease inhibitors (PIs) are shown in Table 1. Selected investigational drugs in existing and new drug classes are shown in Table 2; select drugs from this listing are discussed herein. Figures 1 and 2 show the HIV-1 life cycle and the stages of the life cycle targeted by available drug classes and by drugs from newer and investigational classes such as entry inhibitors and integrase inhibitors. HIV Nucleoside Reverse Transcriptase Inhibitors