 Atazanavirritonavir is one of the preferred antiretroviral agents in all international guidelines. Ritonavir is used as a boosting agents based on its inhibitory effects on CYP3A. This also inhibits CYP3A-mediated metabolism of daclatasvir and when atazanavirritonavir is combined with daclatasvir, it is recommended to reduce the dose of daclatasvir from 60mg QD to 30mg QD. 