How does this medication work? What will it do for me?

Mavacamten belongs to the class of medications called cardiac myosin inhibitors. It is typically used with other medications to treat a type of heart disease called symptomatic hypertrophic cardiomyopathy. This occurs when the heart muscle contracts too much, causing the muscle to become unusually thick. This can cause symptoms such as shortness of breath, chest pain, or irregular heartbeat.

Mavacamten works by relaxing the heart muscles. This allows the heart to pump blood to the rest of your body more easily, improving your symptoms.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

2.5 mg
Each size 2 hard capsule, with a light purple opaque cap and white opaque body, imprinted with "2.5 mg" on the cap and "Mava" on the body, both in radial direction in black, and filled with a white-to-off-white powder, contains 2.5 mg of mavacamten. Nonmedicinal ingredients: croscarmellose sodium, hypromellose, magnesium stearate (non-bovine), mannitol, and silicon dioxide; capsule shell: gelatin (bovine and/or porcine), black iron oxide, red iron oxide, and titanium dioxide; imprinting ink: black iron oxide, potassium hydroxide, propylene glycol, shellac, and strong ammonia solution.

5 mg
Each size 2 hard capsule, with a yellow opaque cap and white opaque body, imprinted with "5 mg" on the cap and "Mava" on the body, both in radial direction in black, and filled with a white-to-off-white powder, contains 5 mg of mavacamten. Nonmedicinal ingredients: croscarmellose sodium, hypromellose, magnesium stearate (non-bovine), mannitol, and silicon dioxide; capsule shell: gelatin (bovine and/or porcine), yellow iron oxide, and titanium dioxide; imprinting ink: black iron oxide, potassium hydroxide, propylene glycol, shellac, and strong ammonia solution.

How should I use this medication?

The recommended starting dose of this medication is 5 mg taken by mouth, once daily. Depending how well this medication works and the side effects you may experience, your doctor may adjust your dose. Swallow the capsule whole with water. It may be taken with or without food.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by your doctor.

If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children. 

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not take this medication if you:

  • are allergic to mavacamten or any ingredients of the medication
  • are taking certain other medications that reduce the effectiveness of this medication
  • are pregnant 

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • cough
  • dizziness
  • fainting
  • fatigue
  • headache

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • symptoms of heart failure (e.g., shortness of breath, tiredness, weakness, swelling in the feet, ankles and legs, chest pain, cough, rapid weight gain, lack of appetite, nausea, rapid or irregular heartbeat, decreased ability to exercise)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Dizziness: Mavacamten may cause dizziness, affecting your ability to drive or operate machinery. Avoid driving, operating machinery, or performing other potentially hazardous tasks until you have determined how you are affected by this medication.

Heart failure: Although mavacamten helps reduce the symptoms of heart failure caused by thickening of the heart walls, it may cause heart failure by other causes. If you find this medication is not helping your symptoms, or your symptoms start to worsen, contact your doctor as soon as possible.

Certain other medications can interfere with how this medication works in the body, causing it to be less effective, or causing too much medication to build up in the body causing side effects. Before taking this medication discuss with your doctor any other medications that you may be taking and how they may affect mavacamten.

Liver function: Liver disease or decreased liver function can cause this medication to build up in the body, causing side effects. If you have reduced liver function, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Pregnancy: Mavacamten may cause harm to a developing baby if it is taken by the mother during pregnancy. Women who may become pregnant should use highly effective birth control while taking mavacamten and for at least 4 months after stopping this medication. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if mavacamten passes into breast milk. If you are breast-feeding and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children. 

What other drugs could interact with this medication?

There may be an interaction between mavacamten and any of the following:

  • apalutamide
  • aprepitant
  • 'azole' antifungals (e.g., fluconazole, itraconazole, ketoconazole)
  • beta-adrenergic blockers (e.g., atenolol, propranolol, sotalol)
  • bosentan
  • cannabidiol
  • cimetidine
  • certain protein kinase inhibitors (e.g., crizotinib, dabrafenib, imatinib)
  • clarithromycin
  • diltiazem
  • disopyramide
  • dronedarone
  • elagolix
  • enzalutamide
  • erythromycin
  • estrogens (e.g., conjugated estrogen, estradiol, ethinyl estradiol)
  • grapefruit juice
  • HIV non-nucleoside reverse transcriptase inhibitors (e.g., efavirenz, etravirine)
  • HIV protease inhibitors (e.g., atazanavir, darunavir, lopinavir, ritonavir)
  • lumacaftor and ivacaftor
  • letermovir
  • mifepristone
  • moclobemide
  • modafinil
  • nirmatrelvir
  • progestins (e.g., drospirenone, levonorgestrel, medroxyprogesterone, norethindrone)
  • proton pump inhibitors (e.g., esomeprazole, omeprazole)
  • ranolazine
  • rifabutin
  • rifampin
  • St. John's wort
  • seizure medications (e.g., carbamazepine, eslicarbazepine, phenobarbital, phenytoin, primidone)
  • selective serotonin reuptake inhibitors (SSRIs; fluoxetine, fluvoxamine)
  • sirolimus
  • tecovirimat
  • verapamil
  • warfarin

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.

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