Drug Interaction Report

MONITOR: Coadministration with nevirapine may decrease the plasma concentrations and therapeutic efficacy of drugs that are substrates of CYP450 3A4. The proposed mechanism is increased clearance due to nevirapine-mediated induction of CYP450 3A4.

MANAGEMENT: Caution is advised if nevirapine is used concomitantly with drugs that are CYP450 3A4 substrates. Dosage adjustments as well as clinical and laboratory monitoring of coadministered drugs should be considered whenever nevirapine is added to or withdrawn from therapy.

Although they are often combined in clinical practice, the concomitant use of beta-2 adrenergic agonists and corticosteroids may result in additive hypokalemic effects. Since beta-2 agonists can sometimes cause QT interval prolongation, the development of hypokalemia may potentiate the risk of ventricular arrhythmias including torsade de pointes. However, clinical data are limited, and the potential significance is unknown. Patients who are receiving systemic or nebulized formulations of beta-2 agonists, high dosages of inhaled beta-2 agonists, or systemic corticosteroid therapy may be at a greater risk of developing hypokalemia.