Drug Interaction Report

MONITOR: Coadministration with miconazole may increase the plasma concentrations of drugs that are substrates of CYP450 3A4. The mechanism is decreased clearance due to inhibition of CYP450 3A4 activity by miconazole, which is thought to be a relatively potent inhibitor of the isoenzyme. No formal drug interaction studies have been conducted with miconazole buccal tablets. Although systemic absorption following mucous membrane exposure is limited, the potential for interaction with drugs metabolized by CYP450 3A4 cannot be ruled out.

MANAGEMENT: Caution is advised if miconazole must be used concurrently with medications that undergo metabolism by CYP450 3A4, particularly those with a narrow therapeutic range. Dosage adjustments as well as clinical and laboratory monitoring may be appropriate for some drugs whenever miconazole is added to or withdrawn from therapy.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.