Coadministration with ritonavir increased doravirine AUC by ~3.5 fold and Cmin by ~2.9 fold. No dose adjustment of doravirine is required as phase I trials showed a good tolerability of doravirine with up to a 3-4 fold increase in exposure. Coadministration of doravirine (50 mg single dose; half the recommended approved dose) with ritonavir (100 mg twice daily) increased doravirine AUC, Cmax and C24 by 254%, 31% and 191%, respectively (n=8).