Mavacamten

Introduction Overview

Generic Name

mavacamten

Brand Name

Camzyos

Dosage Form

oral capsules

Drug Class

Miscellaneous cardiovascular agents

Pharmacokinetics

Absorption:
Mavacamten, marketed as Camzyos, is administered orally in capsule form and demonstrates good bioavailability upon oral administration. Following oral intake, absorption is sufficient to achieve therapeutically relevant plasma concentrations. Peak plasma concentrations are generally achieved within hours of dosing. Food intake does not significantly alter the extent of absorption, allowing for flexible administration with or without meals. The pharmacokinetic profile supports a once-daily dosing regimen, promoting patient adherence in chronic management of obstructive hypertrophic cardiomyopathy (HCM).

Distribution:
Once absorbed, mavacamten exhibits a moderate volume of distribution, indicating distribution beyond the vascular compartment into tissues, including the myocardium. It exhibits high plasma protein binding, predominantly to serum albumin, which may influence its pharmacodynamics and interactions with other highly protein-bound agents. Penetration into cardiac muscle tissue is a critical aspect of its therapeutic action, ensuring adequate concentrations at the site of the cardiac myosin motor protein targets. The pharmacokinetic distribution parameters have been characterized in clinical studies, supporting effective cardiac exposure necessary for clinical efficacy.

Metabolism:
Mavacamten undergoes extensive hepatic metabolism primarily via the cytochrome P450 enzyme system, with CYP2C19 and CYP3A4 playing significant roles. This metabolism results in inactive metabolites excreted renally and hepatically. Genetic polymorphisms affecting CYP2C19 can influence mavacamten plasma levels, necessitating dose adjustments in poor metabolizers to mitigate the risk of excessive pharmacologic effects and adverse events. Moreover, concomitant administration of CYP2C19 or CYP3A4 inhibitors or inducers significantly affects mavacamten metabolism, requiring careful monitoring and potential dose modification.

Elimination:
The elimination half-life of mavacamten supports once-daily dosing, with steady-state plasma concentrations achieved after several days of use. The drug and its metabolites are eliminated via renal and biliary routes. Renal clearance constitutes a minor elimination pathway given predominant metabolism; however, caution is advised in patients with significant renal impairment until further clinical data are available. Hepatic metabolism and biliary excretion are major elimination mechanisms. The pharmacokinetic properties necessitate regular monitoring for cardiac function changes to prevent adverse effects related to cardiac muscle relaxation or systolic dysfunction.

Dosage Forms

Available Dosage Forms:
Camzyos is available exclusively in oral capsule formulations. The capsules are supplied in multiple strengths to facilitate individualized dose titration based on therapeutic response and tolerability. The available capsule strengths are:
- 2.5 mg
- 5 mg
- 10 mg
- 15 mg

Dosages for Adults and Adolescents:
Camzyos is indicated for adult patients with symptomatic obstructive hypertrophic cardiomyopathy. The initial recommended oral dose is 5 mg once daily. Dose adjustments should be made cautiously and guided by functional assessments such as echocardiography, specifically measuring left ventricular ejection fraction (LVEF) and left ventricular outflow tract gradient, to optimize therapeutic outcomes and minimize risk of adverse effects. Subsequent doses can be titrated to 2.5 mg, 5 mg, 10 mg, or 15 mg once daily based on patient response and tolerability. In patients who are concomitantly taking moderate CYP2C19 inhibitors or strong CYP3A4 inhibitors, a reduced starting dose of 2.5 mg daily is recommended.

Specific Patient Populations:
While efficacy and safety in pediatric populations have not been established, Camzyos is currently not recommended for use in children. Caution is warranted in patients with hepatic or renal impairment; although specific dose adjustments are not fully characterized, careful monitoring is essential. Furthermore, Camzyos therapy requires enrollment in the FDA-mandated REMS program due to risks associated with excessive cardiac muscle relaxation leading to heart failure. Pregnancy requires special consideration, with effective contraception recommended during treatment and for at least four months after cessation of therapy, based on preclinical evidence of potential fetal harm.

Mechanism Of Action

Camzyos (mavacamten) exerts its therapeutic effect through selective inhibition of cardiac myosin, a motor protein integral to cardiac muscle contraction. The molecular mechanism involves reversible binding to the myosin heads in heart muscle cells, preventing their interaction with actin filaments, thereby decreasing the number of myosin-actin cross-bridges formed during the contraction cycle. This targeted inhibition reduces hypercontractility, a hallmark of obstructive hypertrophic cardiomyopathy, alleviating undue myocardial stress and excessive contraction.

At the cellular level, by modulating the actin–myosin interaction, mavacamten shifts cardiomyocyte function towards a more relaxed state, effectively improving myocardial compliance. This reduction in contractile force leads to decreased left ventricular outflow tract obstruction, enhancing ventricular filling during diastole and thereby increasing stroke volume. The drug's action allows improved cardiac efficiency and reduced symptoms such as dyspnea and exercise intolerance commonly observed in HCM patients.

The biochemical interaction of mavacamten is allosteric and reversible, ensuring the capacity for dynamic modulation of cardiac contraction rather than permanent suppression. This specificity limits off-target effects on skeletal muscle myosins and smooth muscle, conferring a favorable safety profile while directly addressing the underlying pathophysiology of obstructive HCM.

Clinical implications of this mechanism include symptom improvement, enhanced functional capacity as demonstrated in clinical trials, and potential remodeling of hypertrophied myocardium over prolonged therapy. Comparative to other therapeutic modalities for HCM, such as beta-blockers or calcium channel blockers that only attenuate heart rate or reduce contractility non-specifically, mavacamten provides a novel, mechanism-based intervention. Further studies continue to elucidate its long-term benefits and impact on disease progression.

Pharmacological Actions

Selective inhibition of cardiac myosin ATPase activity, reducing hypercontractility of cardiac muscle.
Allosteric and reversible binding to cardiac myosin, preventing actin–myosin cross-bridge formation.
Reduction of left ventricular outflow tract obstruction by decreasing myocardial contractile force.
Improvement of diastolic filling and ventricular compliance through myocardial relaxation.
Modulation of cardiac muscle energetics, potentially reducing myocardial oxygen consumption.
Decreased interventricular septal thickness and possible reversal of pathological hypertrophy with chronic therapy.
Attenuation of symptoms associated with obstructive hypertrophic cardiomyopathy, including dyspnea and chest pain.
Improvement in exercise capacity and functional status in patients with symptomatic obstructive HCM.
Non-skeletal muscle selective action, reducing potential for systemic muscular adverse effects.
Influences cardiac output by balancing contractility and ventricular filling.
Unique novel mechanism compared to traditional negative inotropes used in HCM treatment.
Reduction in risk factors associated with arrhythmia due to improved ventricular mechanics.
Potential impact on cardiac remodeling markers observed in clinical studies.

Therapeutic Or Clinical Uses

Treatment of symptomatic obstructive hypertrophic cardiomyopathy (HCM) in adults.
Improvement of exercise capacity and functional status in patients with NYHA class II-III obstructive HCM.
Reduction of symptoms such as shortness of breath, chest pain, fatigue, and fainting associated with HCM.
Management of left ventricular outflow tract obstruction to improve cardiac hemodynamics.
Adjunct therapy to standard beta-blocker or calcium channel blocker regimens in obstructive HCM.
Potential modification of disease progression by reducing pathological myocardial hypertrophy.
Improvement in quality of life through enhanced physical activity tolerance.
Use in patients contraindicated or intolerant to invasive procedures such as septal reduction therapies.
Therapeutic intervention to reduce outflow tract gradients measured by echocardiography and cardiac MRI.
Treatment option within FDA-approved indications following thorough cardiac function monitoring.
Part of integrated management strategy involving cardiac imaging and symptom evaluation.
Supportive therapy to reduce hospitalization rates for heart failure symptoms in obstructive HCM.
Available under REMS program to ensure safe use and monitoring of potential cardiac adverse events.
Utilized in specialized cardiovascular centers with expertise in HCM management.

Side Or Adverse Effects

Dizziness occurring in approximately 27% of patients, potentially impacting daily activities.
Syncope (fainting) reported in about 6% of users, necessitating caution in patients with arrhythmias.
Heart failure symptoms including shortness of breath, swelling, fatigue, and chest pain, requiring immediate medical attention.
Risk of left ventricular systolic dysfunction due to excessive cardiac muscle relaxation.
Allergic reactions presenting as urticaria, facial swelling, or respiratory distress that warrant emergency intervention.
Potential for drug-induced reductions in left ventricular ejection fraction necessitating regular echocardiographic monitoring.
Hypotension due to reduced cardiac output in sensitive patients.
Fatigue beyond baseline cardiac disease manifestations.
Possibility of drug interactions leading to enhanced adverse effects or reduced therapeutic efficacy.
Gastrointestinal disturbances reported in clinical trials, though infrequent.
Potential exacerbation of pre-existing heart rhythm abnormalities.
Increased risk of adverse events when combined with certain CYP450 inhibitors or inducers.
Unknown long-term safety profile in pediatric populations.
Possible teratogenicity as indicated by pregnancy precautions.
Headache and malaise reported but infrequently and generally mild.

Precautions

Enroll in and comply with the Camzyos REMS program due to risk of heart failure with treatment.
Undergo baseline and regular echocardiographic assessments of left ventricular ejection fraction and left ventricular outflow tract gradient.
Use caution in patients with pre-existing heart failure or reduced ejection fraction; therapy may exacerbate these conditions.
Adjust starting dose in patients taking moderate CYP2C19 or strong CYP3A4 inhibitors to reduce overdose risks.
Avoid abrupt discontinuation to prevent rebound worsening of cardiac function.
Monitor for signs of heart failure and promptly report symptoms such as dyspnea, swelling, or chest pain.
Use effective contraception during treatment and for at least 4 months after last dose due to potential teratogenicity.
Consider potential drug-drug interactions, especially with CYP450 modulators and cardiac medications.
Avoid use in pediatric patients due to lack of safety and efficacy data.
Be cautious in patients with active infections or arrhythmias, as risk of heart failure is increased.
Inform healthcare providers of all concurrent medications including over-the-counter and herbal supplements.
Regularly assess renal and hepatic function during therapy due to metabolism and elimination pathways.
Educate patients on adherence to dosing schedule and avoidance of missed or double doses.
Advise patients about possible dizziness and syncope, with precautions to minimize injury risk.
Evaluate pregnancy status before initiation and counsel on breastfeeding considerations.

Warnings

Boxed Warning for risk of heart failure associated with excessive cardiac muscle relaxation.
Heart failure can manifest as shortness of breath, fatigue, swelling, chest pain, or arrhythmias requiring emergency care.
Regular echocardiograms mandated before treatment initiation and during therapy to monitor cardiac function.
Risk of heart failure elevations in patients experiencing serious infections or arrhythmias during therapy.
Use only under restricted REMS program to ensure safety and appropriate monitoring.
Avoid use in patients with significantly reduced left ventricular ejection fraction unless under strict specialist supervision.
Potential for serious drug interactions increasing risk of cardiac adverse events.
May cause fetal harm; pregnancy must be avoided during treatment.
Discontinue therapy temporarily or permanently if significant left ventricular systolic dysfunction develops.
Inform patients of symptoms suggestive of heart failure and instruct immediate reporting.
Avoid dose escalation without thorough clinical and echocardiographic evaluation.
Concomitant use with certain cardiac medications can elevate risk of left ventricular dysfunction and heart failure symptoms.
Not established as safe or effective in pediatric, pregnant, or breastfeeding populations.
Use caution in patients with a history of irregular heart rhythms or conduction abnormalities.
Monitor for hypersensitivity reactions that may require cessation of therapy.

Contraindication

Known hypersensitivity to mavacamten or any capsule excipients.
Patients with pre-existing severe heart failure or significantly reduced left ventricular ejection fraction.
Use in pediatric patients due to lack of established safety and efficacy.
Pregnancy due to potential teratogenic effects observed in preclinical studies.
Concurrent use with potent CYP2C19 or CYP3A4 inhibitors without dose adjustment due to risk of toxicity.
Patients unable or unwilling to comply with REMS program monitoring requirements.
Severe hepatic impairment pending further clinical data.
Concurrent use of combination cardiac therapies increasing risk of ventricular dysfunction without cardiology oversight.
Patients with active infections who cannot be closely monitored.
Any condition or comorbidity that precludes regular echocardiographic monitoring.
Known significant arrhythmias untreated or uncontrolled prior to therapy initiation.
Concomitant usage with medications known to cause marked negative inotropic effects without appropriate monitoring.
Use during breastfeeding until safety is established.
Patients with history of drug-induced cardiac muscle relaxation adverse reactions to similar agents.

Drug Interactions

Strong or moderate CYP2C19 inhibitors increase mavacamten plasma concentrations, requiring dose reductions.
Strong CYP3A4 inhibitors necessitate reducing starting mavacamten dose to 2.5 mg daily.
CYP2C19 and CYP3A4 inducers can decrease mavacamten plasma levels, potentially reducing efficacy.
Concomitant use with heart medications such as disopyramide, ranolazine, verapamil, or diltiazem with beta blockers increases risk of left ventricular systolic dysfunction and heart failure symptoms.
Mavacamten induces CYP3A4, CYP2C9, and CYP2C19 enzymes, potentially reducing plasma concentrations of substrates metabolized by these pathways.
Progestin and ethinyl estradiol-containing hormonal contraceptives metabolism may be enhanced, reducing contraceptive efficacy.
Combined hormonal contraceptives with ethinyl estradiol and norethindrone are acceptable; others require additional non-hormonal contraception measures during coadministration and for 4 months post-treatment.
Interaction potential with antibiotics such as clarithromycin, rifampin, rifabutin, rifapentine, and telithromycin via CYP450 modulation.
Antifungal agents like itraconazole and ketoconazole may raise mavacamten levels by CYP inhibition.
Antiviral drugs for HIV or hepatitis C (e.g., boceprevir, cobicistat, elvitegravir, lopinavir/ritonavir) can alter mavacamten metabolism.
Certain cancer therapeutics such as apalutamide and enzalutamide may affect mavacamten plasma concentration.
Seizure medications including carbamazepine, oxcarbazepine, phenytoin, and primidone induce enzymes affecting drug levels.
Steroid medications like dexamethasone and prednisone may modify metabolism.
Co-administration with gastric acid reducers such as omeprazole and esomeprazole or cimetidine requires caution due to potential absorption alterations.
Interactions with over-the-counter, herbal supplements, and vitamins are possible, emphasizing the need for comprehensive medication review.

Preparations Of The Drug

Camzyos is available as oral capsules in strengths of 2.5 mg, 5 mg, 10 mg, and 15 mg mavacamten.
Capsules contain inactive ingredients including croscarmellose sodium, hypromellose, magnesium stearate (non-bovine), mannitol, and silicon dioxide.
Capsule shells comprise black iron oxide, gelatin, red iron oxide, titanium dioxide, and yellow iron oxide, ensuring stability and bioavailability.
Packaged for oral administration only; capsules should be swallowed whole without breaking or chewing.
Stored at ambient room temperature ranging from 20°C to 25°C (68°F to 77°F), protecting chemical integrity.
Available through restricted distribution within the Camzyos REMS program to ensure appropriate clinical monitoring.
Bristol-Myers Squibb Company manufactures and distributes Camzyos.
Packaging includes detailed prescribing information and patient brochures outlining dosage, precautions, and monitoring requirements.
Available commercially with prescription and comprehensive healthcare provider safety protocols.
No intravenous or alternative formulations currently approved.
Capsules are designed for once-daily dosing to enhance patient compliance.
Instruct patients on proper handling to avoid capsule damage which could affect drug delivery.
Pharmaceutical formulation optimized for stability, controlled release, and targeted effect within cardiac tissue.