Coadministration has not been studied. Rivaroxaban is a substrate of CYP3A4, P-gp and BCRP. Ritonavir increased rivaroxaban AUC and Cmax by 150% and 60%, respectively. Similar increases in pharmacodynamic effects (i.e., factor Xa inhibition and PT prolongation) were also observed. Significant increases in rivaroxaban exposure may increase bleeding risk. Rivaroxaban label recommends avoiding use with ritonavir. Use alternative if possible.

Coadministration has not been studied. Lorazepam is a substrate of multiple UGTs and its exposure may increase with ombitasvir/paritaprevir/ritonavir due to UGT inhibition. Close monitoring is recommended and decrease lorazepam dose may be required if clinically indicated.

Coadministration has not been studied. LSD (lysergic acid diethylamide) is metabolized to O-H-LSD and N-desmethyl-LSD partly by CYP (unknown isoenzyme). Coadministration could potentially increase LSD concentrations. Ensure the patient is aware of signs/symptoms of LSD toxicity (i.e. hallucinations, agitation, psychosis, flashbacks).

Coadministration has not been studied. The role of CYP450 in the metabolism of dexamfetamine has not been fully described and potent inhibitors of CYP3A4, such as ritonavir, should be used with caution.

Coadministration has not been studied. Tetrahydrocannabinol (THC, the psychoactive component of cannabis) is metabolised mainly by CYP2C9 and to a lesser extent by CYP3A4. Coadministration with ombitasvir/paritaprevir/ritonavir may increase concentrations of THC due to inhibition of CYP3A4 by ritonavir. The patient should be made aware of potential increased side effects.