Mavacamten is a cardiac myosin allosteric modulator that improves symptoms of hypertrophic cardiomyopathy by selectively inhibiting the ATPase activity of cardiac myosin. Its drug interactions mainly involve the CYP enzyme system and specific cardiovascular drugs, necessitating strict monitoring to avoid reduced efficacy or increased toxicity.

1. Effect

Mavacantane reduces the rate of the cross-bridge cycle by reversibly binding to cardiac myosin, thereby reducing myocardial overcontraction and energy consumption. Clinically, it has been shown to significantly improve left ventricular outflow obstruction and cardiac function classification, as well as enhance exercise tolerance.

This drug exhibits a dose-dependent therapeutic effect. After 4 weeks of treatment, a moderate decrease in left ventricular ejection fraction (LVEF) may be observed, necessitating regular echocardiographic monitoring. Long-term use can reverse myocardial hypertrophy and delay disease progression.

2. Drug interactions

(1) CYP metabolism-related

Strong CYP2C19 inhibitors (such as fluconazole): May increase the plasma concentration of maravacanthan by more than 2 times. Combination use should be avoided or the dosage should be reduced by 50%, and monitoring should be intensified.

CYP2C19 inducers (such as rifampin): May reduce the exposure to mavacantan by 60%. Dose adjustment to the maximum recommended dose is necessary, and efficacy should be evaluated.

(2) Cardiovascular drugs

Beta blockers/calcium channel blockers: May enhance negative inotropic effects. When used in combination, the dosage should be titrated gradually, and cardiac function and blood pressure should be monitored.

Digoxin: Mavacantane may increase its plasma concentration by 20%-30%. During combined use, monitor for symptoms of digoxin toxicity.

(3) Other interactions

Moderate CYP3A4 inhibitors (such as verapamil): May slightly increase the concentration of maravacanthan, and it is recommended to reduce the starting dose to 5mg.

Grapefruit products: May increase drug exposure by inhibiting CYP3A4, and should be avoided during treatment.