NON-NUCLEOSIDE INHIBITORS - A class if anti-HIV drugs usually used in combination with other antiretroviral medications. Non-nucleoside reverse transcriptase inhibitors exert their beneficial effect by interfering with the production of new virus particles. This is achieved by inhibiting the enzyme, reverse transcriptase. This enzyme allows the virus to "read" its own RNA to produce viral DNA (from which it makes new virus particles). Without this enzyme the virus cannot reproduce. Examples of drugs in this class include nevirapine (Viramune), delavirdine (Rescriptor), and efavirenz (Sustiva). The hepatic cytochrome p450 enzymes metabolize all of these medicines, so drug interactions can occur with protease inhibitors and other medications.