Rilpivirine-13C6 (R278474-13C6) is 13C labeled Rilpivirine. Rilpivirine (R278474) is a potent and specific diarylpyrimidine (DAPY) non-nucleoside reverse transcriptase inhibitor (NNRTI). Rilpivirine has high antiviral activity against wild-type HIV (EC50=0.4 nM) and mutant viruses (EC50=0.1-2.0 nM). Rilpivirine has a high genetic barrier to resistance development of HIV[1][2].