Drug Interaction Report

MONITOR: Concomitant use of belimumab and biologic therapies, including B-cell targeted therapies with immunosuppressant effects may lead to an increase in the rate of severe adverse events and serious infections. In a double-blind, randomized, placebo-controlled, phase 3 trial in adults with systemic lupus erythematosus (SLE) receiving belimumab, the addition of rituximab was associated with serious adverse events in 22.2% and serious infections in 9% of patients, compared to 13.9% and 2.8% of patients, respectively, in the placebo add-on group. Clinical data for other B-cell targeted therapies are unavailable.

MANAGEMENT: According to the manufacturer of belimumab, available data do not support the coadministration of belimumab with rituximab in patients with SLE. Caution and monitoring for adverse reactions, particularly infections, is advised if concomitant use of belimumab with other biologic therapies with immunosuppressant effects, particularly B-cell targeted therapies including but not limited to ocrelizumab, ofatumumab, or obinutuzumab. Some authorities advise against their concomitant use.

ADJUST DOSING INTERVAL: Food may reduce the oral bioavailability of ixazomib. A food effect study found that administration of a single 4 mg dose of ixazomib with a high-fat meal decreased ixazomib peak plasma concentration (Cmax) by 69% and systemic exposure (AUC) by 28%.

MANAGEMENT: Ixazomib should be taken at least one hour before or two hours after eating. On days when both ixazomib and dexamethasone are administered, advise patients to separate dosing times, since dexamethasone should be taken with food while ixazomib should be taken on an empty stomach.