Drug Interactions between berotralstat and fluticasone / vilanterol

MONITOR: Coadministration with moderate inhibitors of CYP450 3A4 may increase the systemic exposure to fluticasone following intranasal administration or oral inhalation. Fluticasone undergoes extensive first-pass and systemic metabolism via CYP450 3A4, thus inhibition of the isoenzyme may significantly increase systemic bioavailability of the drug. However, the extent of interaction may depend on the route of fluticasone administration and the specific formulation. Multiple case reports describe instances of adrenal insufficiency and Cushing's syndrome associated with concomitant use of inhaled fluticasone and the azole antifungal fluconazole, a moderate CYP450 3A4 inhibitor.

MANAGEMENT: Monitor for signs and symptoms of hypercorticism if intranasal or orally inhaled fluticasone is coadministered with a moderate inhibitor of CYP450 3A4. Signs and symptoms of hypercorticism include acne, striae, thinning of the skin, easy bruising, moon facies, dorsocervical "buffalo" hump, truncal obesity, increased appetite, acute weight gain, edema, hypertension, hirsutism, hyperhidrosis, proximal muscle wasting and weakness, glucose intolerance, exacerbation of preexisting diabetes, depression, and menstrual disorders. Other systemic glucocorticoid effects may include adrenal suppression, immunosuppression, posterior subcapsular cataracts, glaucoma, bone loss, and growth retardation in children and adolescents. Signs and symptoms of adrenal insufficiency include anorexia, hypoglycemia, nausea, vomiting, weight loss, muscle wasting, fatigue, weakness, dizziness, postural hypotension, depression, and adrenal crisis manifested as inability to respond to stress (e.g., illness, infection, surgery, trauma). Systemic glucocorticoids may be necessary until adrenal function recovers.

MONITOR: Coadministration with berotralstat may increase the plasma concentrations and effects of drugs that are substrates of CYP450 3A4 and/or 2D6. The mechanism is decreased clearance due to inhibition of CYP450 3A4 and 2D6 activity by berotralstat. Berotralstat is considered a moderate inhibitor of CYP450 3A4 and 2D6. In drug interaction studies, berotralstat reportedly increased the peak plasma concentration (Cmax) and systemic exposure (AUC) of the sensitive CYP450 3A4 substrate midazolam by approximately 1.5-fold and 2.25-fold, respectively, and the CYP450 3A4 substrate amlodipine by approximately 1.5-fold and 1.75-fold, respectively. It increased the Cmax and AUC of the sensitive CYP450 2D6 substrate dextromethorphan by approximately 2.9-fold and 2.7-fold, respectively, and the CYP450 2D6 substrate desipramine by 1.7-fold and 1.9-fold, respectively. Clinical data are not available.

MANAGEMENT: Caution is advised when berotralstat is coadministered with drugs that are substrates of CYP450 3A4 and/or 2D6, particularly those with a narrow therapeutic index. Clinical and laboratory monitoring are recommended following the initiation of berotralstat, and the individual dosages of the concomitant agents adjusted as needed.

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.