TMC278 (rilpivirine) is a new investigational non nucleoside reverse transcriptase inhibitor (NNRTI) discovered and in development by Tibotec, a division of Johnson & Johnson. Data from clinical development (Phase IIB) suggest that TMC278 has a similar efficacy and better side-effect profile as compared to other, older, NNRTIs, such as efavirenz. Like TMC125 (etravirine), TMC278 is a diarylpyrimidine (DAPY - a class of molecule that resembles the pyrimidine nucleotides found in DNA, and which have shown potency in inhibiting the activity of HIV reverse transcriptase).