Summary

Clarithromycin can significantly increase mometasone levels by inhibiting the CYP3A4 enzyme responsible for mometasone metabolism. This interaction may lead to enhanced corticosteroid effects and increased risk of systemic adverse reactions, particularly with prolonged use or higher doses.

Introduction

Mometasone is a potent synthetic corticosteroid used topically for inflammatory skin conditions, intranasally for allergic rhinitis, and by inhalation for asthma management. It belongs to the class of glucocorticoids and works by reducing inflammation and immune responses. Clarithromycin is a macrolide antibiotic commonly prescribed for respiratory tract infections, skin infections, and Helicobacter pylori eradication. It works by inhibiting bacterial protein synthesis and is known to be a strong inhibitor of the cytochrome P450 3A4 (CYP3A4) enzyme system.

Mechanism of Interaction

The interaction between mometasone and clarithromycin occurs through CYP3A4 enzyme inhibition. Mometasone is primarily metabolized by the CYP3A4 enzyme system in the liver. Clarithromycin is a potent CYP3A4 inhibitor that can significantly reduce the metabolism of mometasone, leading to increased plasma concentrations and prolonged half-life of the corticosteroid. This pharmacokinetic interaction can result in enhanced and prolonged corticosteroid effects, even with topical or inhaled mometasone formulations that typically have minimal systemic absorption.

Risks and Symptoms

The primary clinical risks include increased systemic corticosteroid effects such as adrenal suppression, Cushing's syndrome, hyperglycemia, and increased susceptibility to infections. Patients may experience symptoms like weight gain, mood changes, elevated blood pressure, and delayed wound healing. The risk is particularly elevated with prolonged concurrent use, higher doses of either medication, or in patients with compromised liver function. Topical and inhaled mometasone formulations, while generally having low systemic bioavailability, may still pose risks when combined with strong CYP3A4 inhibitors like clarithromycin.

Management and Precautions

Healthcare providers should carefully evaluate the necessity of concurrent use and consider alternative antibiotics when possible. If co-administration is required, patients should be monitored for signs of corticosteroid excess, including blood glucose levels, blood pressure, and signs of adrenal suppression. Consider reducing mometasone dose or frequency during clarithromycin treatment. Limit the duration of concurrent therapy when feasible. Patients should be educated about potential symptoms of increased corticosteroid effects and advised to report any concerning symptoms promptly. Regular follow-up is recommended, especially for patients on long-term mometasone therapy or those with risk factors for corticosteroid complications.

Clarithromycin interactions with food and lifestyle

Clarithromycin can be taken with or without food. However, taking clarithromycin with food may help reduce stomach upset and gastrointestinal side effects. Grapefruit juice should be avoided as it may increase clarithromycin blood levels and potentially increase the risk of side effects. Alcohol does not have a direct interaction with clarithromycin, but it's generally recommended to limit alcohol consumption while taking antibiotics to support immune system function and recovery.