Drug Interaction Report

MONITOR CLOSELY: The use of the CD20-directed cytolytic antibody ublituximab with other immune-modulating or immunosuppressive therapy, including immunosuppressant doses of corticosteroids may increase the risk of infections. Adverse events most commonly reported with ublituximab alone included upper respiratory tract infections and urinary tract infections. However, serious and life-threatening infections, such as hepatitis B virus (HBV) reactivation have been reported in relapsing multiple sclerosis (RMS) controlled clinical trials with ublituximab, as well as fatal infections. In addition, Progressive Multifocal Leukoencephalopathy (PML) due to JC virus infection, fulminant hepatitis, hepatic failure, and death caused by HBV reactivation have been reported in patients treated with other anti-CD20 antibodies; however, these adverse events were not reported in RMS controlled clinical trials with ublituximab.

MANAGEMENT: The increased risk of additive immunosuppression should be considered if coadministering ublituximab with other immunosuppressive therapy. In addition, the prolonged immunosuppressant effects and mode of action of other immunosuppressant drugs such as daclizumab, fingolimod, natalizumab, teriflunomide, or mitoxantrone should be considered prior to starting ublituximab therapy. Patients should be advised to immediately notify their doctor if they develop signs or symptoms of infection, including HBV reactivation, upper or lower respiratory tract infection, urinary tract infections, herpes-related infection, or PML.

ADJUST DOSING INTERVAL: Food enhances the oral absorption and bioavailability of ribavirin. Administration of a single oral dose of ribavirin following a high-fat meal delayed absorption (Tmax was doubled) but increased the mean peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) by up to 70% compared to administration in the fasting state.

MANAGEMENT: To ensure maximal oral absorption, ribavirin should be administered with or immediately after a meal.