Drug Interactions between atazanavir / cobicistat and betrixaban

GENERALLY AVOID: Coadministration with inducers of P-glycoprotein (P-gp) may reduce the systemic exposure and pharmacodynamic effects of betrixaban, which is a substrate of the efflux transporter. Data evaluating this interaction are not available.

MANAGEMENT: The use of betrixaban with P-gp inducers should generally be avoided. If use is unavoidable, pharmacologic response to betrixaban should be monitored closely.

MONITOR: Coadministration with inhibitors of P-glycoprotein (P-gp) may increase the plasma concentrations of betrixaban, which is a substrate of the efflux transporter. When administered with the potent P-gp inhibitor verapamil, betrixaban peak plasma concentration (Cmax) increased by nearly 5-fold and systemic exposure (AUC) increased by approximately 3-fold compared to betrixaban administered alone. When given with ketoconazole, another P-gp inhibitor, betrixaban Cmax and AUC increased by a little more than 2-fold each. In the Acute Medically Ill Prevention with Extended Duration Betrixaban (APEX) Study, use of betrixaban at a 50% dosage reduction in combination with P-gp inhibitors or in the presence of severe renal impairment was associated with increased relative risks of bleeding, including major bleeding, compared to treatment with enoxaparin.

MANAGEMENT: Caution is advised when betrixaban is used with P-gp inhibitors. Closer monitoring of the pharmacologic effects of betrixaban may be appropriate whenever a P-gp inhibitor is added to or withdrawn from therapy. Patients should be routinely evaluated for signs and symptoms suggesting blood loss such as a drop in hemoglobin and/or hematocrit, hypotension, or fetal distress (in pregnant women). Concomitant use of betrixaban with P-gp inhibitors should be avoided in patients with severe renal impairment (CrCl<30 mL/min).