NNRT inhibitors stop HIV from multiplying by blocking the reverse transcriptase enzyme, an enzyme that converts HIV's genetic material (RNA) into the form of DNA. Non-nucleoside reverse ranscriptase inhibitors physically hinder the reverse transcriptase from functioning.

These drugs have not been approved by the Food and Drug Administration(FDA) for use against HIV.

(+)-Calanolide A by Sarawak MediChem Pharmaceuticals (Phase II)

Derived from a rain forest plant, (+)-Calanolide AIt can easily cross the blood-brain barrier, and seems to stay in the bloodstream for a long time.

For more information, please visit Calanolide A.

Capravirine (AG1549, formerly S- 1153) by Agouron Pharmaceuticals (Phase II)

Capravirine appears to be about 10 times stronger than other nevirapine(NNRTI) or delavirdine(NNRTI) against wild type virus. It takes HIV for 2 or 3 mutations to develop resistance to capravirine, compared to just one mutation for current NNRTIs.

GW5634 by GlaxoSmithKline (Phase I)

GW5634, a prodrug of GW8248, is broken down in the body to produce GW8248.

MIV-150 by Medivir and Chiron (Phase II)

MIV-150 is effective against strains of HIV that have resistance to current NNRTIs. It takes a long time for HIV to develop resistance to MIV-150.

TMC125 by Tibotec Virco (Phase II)

TMC125 is active against some strains of HIV that are resistant to other NNRTIs. It takes longer for HIV to develop resistance to TMC125 than to the first NNRTI drugs. It is being studied in Phase II trials.