The most frequently reported adverse events (AEs) were dermatitis contact, back pain, blood pressure decrease, headache and nausea. The majority of AEs were mild in intensity with few moderates and no severe. No increase in AEs was observed in relation to increasing dose. The PK analysis indicated that the AUC and Cmax increase in a more than dose proportional manner over the 25 to 600 mg doses with the AUC and Cmax at 600 mg being respectively 62- and 92-fold higher than at the 25 mg dose. Proportionality in AUC and Cmax was noticed between the 600 and 800 mg doses. The elimination half-life, for all cohorts, was ca. 5 hours. At the 400 mg dose, there was no significant food-effect on any of the measured PK parameters. There was a ritonavir-effect as the PK parameters for terminal half-life, AUC and Cmax were 3-, 19- and 6-fold higher, respectively, when 25 mg VCH-286 was co-administered with 100 mg ritonavir. This observation is consistent with the fact that VCH-286 is a CYP3A4 substrate.