[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Cardiac myosin inhibitors](https://durgical.com/en/pharmacology/classes/cardiac-myosin-inhibitors/) › Mavacamten # Mavacamten ## Cardiac myosin inhibitors? Cardiac myosin inhibitors ## Pregnancy: contraindicated? May harm the fetus: a pregnancy test is done before starting and effective non-hormonal contraception is used during treatment and for several months after stopping. The first cardiac myosin inhibitor: an oral drug that reduces excess heart contraction in symptomatic obstructive hypertrophic cardiomyopathy. Updated Nov 1, 2026 ## Quick facts **Group** [Cardiac myosin inhibitors](https://durgical.com/en/pharmacology/classes/cardiac-myosin-inhibitors/) **Target** Cardiac β-myosin (MYH7), motor domain ATPase **Key effects** Dizziness · Fainting **Monitor** Echocardiography · Symptoms of heart failure **ATC** C01EB24 No doses: the clinician sets them by the current guideline. On this page - The basics Mechanism of action - Indications - Adverse effects - Pharmacokinetics - Memory aid - Clinical What the labels mean - Safety Contraindications - Key interactions - What is monitored - Administration and safety - Pregnancy and breastfeeding - Nursing care - Study Test yourself - Connections Connections ## Mechanism of action ✂**Cardiac β-myosin (MYH7), motor domain ATPase**Mavacamten ⓘ The figure shows mavacamten bound to human β-cardiac myosin in the folded, energy-saving 'interacting-heads' state. **Target in 3D:** Cardiac β-myosin (MYH7), motor domain ATPase. PDB structure 9YP9 (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/9YP9) · Drag to rotate · pinch to zoom Mavacamten is an allosteric, reversible and selective inhibitor of cardiac myosin ATPase. It lowers the number of myosin heads that can enter force-producing 'on-actin' states and shifts the myosin population towards the energy-sparing super-relaxed state. Systolic hypercontractility and the dynamic left ventricular outflow tract obstruction fall, and diastolic relaxation improves. - Binds cardiac myosin at an allosteric site - Fewer myosin heads bind actin (super-relaxed state) - Contraction is less forceful; outflow obstruction eases - Symptoms and exercise capacity improve ## Indications - Symptomatic obstructive hypertrophic cardiomyopathy in adults, to improve symptoms and functional capacity [Hypertrophic cardiomyopathy →](https://durgical.com/en/conditions/hypertrophic-cardiomyopathy/) ## Adverse effects ### Common - Dizziness - Fainting (syncope) ### Serious (rare, important) - Systolic heart failure from excessive reduction in contractility - Fetal harm ## Contraindications - Starting when the left ventricular ejection fraction is already reduced (it is reserved for a preserved ejection fraction) - Use with drugs that strongly change its levels (certain CYP2C19 or CYP3A4 inhibitors or inducers) - Pregnancy ## Key interactions **CYP2C19 inhibitors (omeprazole, esomeprazole, fluconazole, some antidepressants) and CYP3A4 inhibitors; cimetidine** Raise mavacamten levels and the risk of heart failure. **CYP inducers such as St John's wort** Lower mavacamten levels and its effect. **Hormonal contraceptives** Made less effective; a non-hormonal or additional method is used during treatment and for months after. ## What is monitored - Echocardiography (ejection fraction) before starting and during treatment - Symptoms of heart failure: breathlessness, fatigue, swelling, rapid weight gain - New medicines or supplements (interactions) - Pregnancy test before starting ## Administration and safety - Oral, once a day, with or without food, swallowed whole. - Available only through a restricted programme (REMS) because of heart failure risk. - The dose is adjusted according to echocardiography; changes take weeks to show. - Any new prescription, over-the-counter acid reducer or herbal product is checked for interactions first. ## Pregnancy and breastfeeding May harm the fetus: a pregnancy test is done before starting and effective non-hormonal contraception is used during treatment and for several months after stopping. ## Nursing care - Before: echocardiogram, pregnancy test, full medicine list (including omeprazole and St John's wort). - During: breathlessness, oedema, weight gain, palpitations; intercurrent illness or new arrhythmia. - Teach to report heart failure symptoms promptly. - Teach that hormonal contraception is not reliable on mavacamten. ## Pharmacokinetics **Absorption** Oral capsule. **Metabolism** Extensive, mainly by CYP2C19 and also CYP3A4; CYP2C19 poor metabolizers have much higher exposure. **Half-life** Very long (days, and longer in CYP2C19 poor metabolizers), so changes take weeks to settle (G&G). ## Memory aid MAVAcamten = 'MAke VAlves Calm': it quiets an overpumping heart. Too quiet = heart failure, so the echo is checked again and again. ## Test yourself Think of the answer, then tap the question to see it. ## Which disease does mavacamten treat and what is its target? Symptomatic obstructive hypertrophic cardiomyopathy; it inhibits cardiac β-myosin. ## Why is mavacamten distributed through a restricted programme? It can reduce contractility too much and cause systolic heart failure, so echocardiographic monitoring is mandatory. ## Why can omeprazole be a problem with mavacamten? It inhibits CYP2C19, raising mavacamten levels and the risk of heart failure. ## What advice about contraception goes with mavacamten? Hormonal contraceptives are less effective, so another method is needed during treatment and for months after. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/pharmacology/mavacamten/) [More Pharmacology questions →](https://durgical.com/en/practice/?f=pharmacology) ## What the labels mean **Pregnancy: contraindicated** May harm the fetus: a pregnancy test is done before starting and effective non-hormonal contraception is used during treatment and for several months after stopping. ## Connections ## Related conditions 1 - [Hypertrophic cardiomyopathy](https://durgical.com/en/conditions/hypertrophic-cardiomyopathy/) [← Back to the class: Cardiac myosin inhibitors](https://durgical.com/en/pharmacology/classes/cardiac-myosin-inhibitors/) Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given. Sources: [Mavacamten: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a622047.html) (MedlinePlus (U.S. National Library of Medicine), 2022); [Cryo-EM structure of human beta-cardiac myosin bound to mavacamten in the interacting-heads motif and S2-FH docked state](https://www.rcsb.org/structure/9YP9) (RCSB Protein Data Bank, 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=C01EB24) (WHO Collaborating Centre for Drug Statistics Methodology, 2026). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/pharmacology/mavacamten/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/mavacamten/