Aficamten

FDA label, Cytokinetics Inc., oral, effective 2025-12-16. Full label on DailyMed

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Quoted from the FDA label. Product labels differ by manufacturer and change over time; confirm against the label for the product you are using.

Boxed warning

WARNING: RISK OF HEART FAILURE MYQORZO reduces left ventricular ejection fraction (LVEF) and can cause heart failure due to systolic dysfunction [see Warnings and Precautions (5.1) ]. Echocardiogram assessments are required prior to and during treatment with MYQORZO to monitor for systolic dysfunction. Initiation of MYQORZO in patients with LVEF <55% is not recommended. Decrease the dose of MYQORZO if LVEF is <50% and ≥40% [see Dosage and Administration (2.2) and Warnings and Precautions (5.1) ] . Interrupt the dose of MYQORZO if LVEF <40% or if the patient experiences heart failure symptoms or worsening clinical status due to systolic dysfunction [see Dosage and Administration (2.2) ].

Because of the risk of heart failure due to systolic dysfunction, MYQORZO is available only through a restricted program under a Risk Evaluation and Mitigation Strategy (REMS) called the MYQORZO REMS Program [see Warnings and Precautions (5.2) ]. WARNING: RISK OF HEART FAILURE See full prescribing information for complete boxed warning. MYQORZO can cause heart failure due to systolic dysfunction. ( 5.1 ) Echocardiogram assessments of left ventricular ejection fraction (LVEF) are required before and during MYQORZO use. ( 2.1 ) Initiation in patients with left ventricular ejection fraction (LVEF) <55% is not recommended. ( 2.1 ) Decrease dose if LVEF <50% and ≥40%.

Interrupt dosing if LVEF <40% or if worsening clinical status. ( 2.2 ) MYQORZO is available only through a restricted program called the MYQORZO REMS Program. ( 5.2 )

Dosing in kidney impairment

This label has no separate kidney-impairment dosing section. Check warnings and clinical pharmacology in the full label.

Preparation and administration

Recommended Dosage and Administration The recommended starting dose of MYQORZO is 5 mg orally once daily. Increase the dose every 2 to 8 weeks by 5 mg until a maintenance dose or the maximum recommended dose of 20 mg once daily is achieved. The maintenance dose of MYQORZO is individualized based on the patient's LVEF and LVOT-G.

Recommendations for dosing based on LVEF and LVOT-G criteria are provided in Table 1. [See table below.] Perform an echocardiographic assessment 2 to 8 weeks after initiation of treatment or any dose adjustment (e.g., due to LVEF and LVOT-G criteria or drug interaction). After a treatment interruption due to low LVEF, resume treatment, no earlier than 7 days, when LVEF ≥55% and re-initiate dose titration at the starting dose of 5 mg (see Table 1 ).

After the maintenance dose has been established, assess LVEF and Valsalva LVOT-G every 6 months, or every 3 months in patients with LVEF <55% to ≥50%. Consider monitoring LVEF and adjust the dose per Table 1 as needed, in patients with an intercurrent illness (e.g., severe infection or COVID-19), new arrhythmia (e.g., new or uncontrolled atrial fibrillation or other uncontrolled tachyarrhythmia) or any other conditions that may impair systolic function.

Do not increase the dose until the intercurrent illness or new arrhythmia has resolved or stabilized. MYQORZO should be taken once daily with or without meals at about the same time every day. Swallow tablets whole.

Drug interactions

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Label text (7 paragraphs)

Drugs that inhibit multiple pathways of MYQORZO elimination, strong CYP2C9 inhibitors, or moderate-to-strong CYP3A inducers may increase risk of heart failure. MYQORZO dose reduction and additional monitoring may be required when initiating or discontinuing these drugs. ( 2.3 , 7.1 ) 7.1. Potential for Other Drugs to Affect Plasma Concentrations of MYQORZO Aficamten is primarily metabolized by CYP2C9 and, to a lesser extent by CYP3A, CYP2D6, and CYP2C19.

Concomitant administration of drugs that inhibit multiple P450 pathways of aficamten elimination, strong inhibitors of CYP2C9, and moderate-to-strong inducers of CYP3A, may affect the exposure of aficamten [see Warnings and Precautions (5.2) and Clinical Pharmacology (12.3) ] (see Table 2 ). Table 2: Established and Potentially Significant Pharmacokinetic Drug-Drug Interactions with MYQORZO Inhibitors of Multiple CYPs Fluvoxamine Clinical Impact Fluvoxamine is a strong CYP2C19 inhibitor, weak to moderate CYP3A inhibitor, weak CYP2C9 inhibitor, and weak CYP2D6 inhibitor.

Coadministration of fluvoxamine is predicted to increase aficamten exposure, which may increase the risk of developing heart failure due to systolic dysfunction. Prevention or Management Initiate MYQORZO at 5 mg in patients on stable therapy with fluvoxamine. In patients who are on MYQORZO treatment and intend to initiate fluvoxamine: Reduce dose of MYQORZO (i.e., 20 mg to 10 mg, 15 mg to 5 mg, or 10 mg to 5 mg) or continue 5 mg [see Dosage and Administration (2.3) ] . Fluconazole or Voriconazole Clinical Impact Fluconazole is a moderate CYP2C9 inhibitor, moderate CYP3A inhibitor, and strong CYP2C19 inhibitor.

Voriconazole is a strong CYP3A inhibitor, moderate CYP2C19 inhibitor, and weak CYP2C9 inhibitor. Coadministration with fluconazole is observed, and voriconazole is predicted, to increase aficamten exposure, which may increase the risk of developing heart failure due to systolic dysfunction [see Clinical Pharmacology (12.3) ] . Prevention or Management Initiate MYQORZO at 5 mg in patients on stable therapy with fluconazole or voriconazole. In patients currently receiving MYQORZO who intend to initiate fluconazole (if used more than 3 days) or voriconazole: Reduce dose of MYQORZO to 5 mg if they are currently receiving MYQORZO 15 mg or 20 mg.

Avoid concomitant use if currently receiving MYQORZO 5 mg or 10 mg [see Dosage and Administration (2.3) ] . Strong CYP2C9 inhibitors Clinical Impact Coadministration with a strong CYP2C9 inhibitor is predicted to increase the exposure of aficamten, which may increase the risk of developing heart failure due to systolic dysfunction [see Clinical Pharmacology (12.3) ] . Prevention or Management Initiate MYQORZO at 5 mg in patients who are on stable therapy with a strong CYP2C9 inhibitor.

In patients who are on MYQORZO treatment and intend to initiate a strong CYP2C9 inhibitor: Reduce dose of MYQORZO (i.e., 20 mg to 10 mg, 15 mg to 5 mg, or 10 mg to 5 mg) or continue 5 mg [see Dosage and administration (2.3) ]. CYP Inducers Rifampin Clinical Impact Rifampin is a strong CYP3A inducer, strong CYP2C19 inducer, and moderate CYP2C9 inducer. Coadministration of rifampin decreases aficamten exposure, which may reduce the effectiveness of MYQORZO [see Contraindications (4) and Clinical Pharmacology (12.3) ]. Prevention of Management Concomitant use with rifampin is contraindicated.

Other moderate-to-strong CYP3A inducers Clinical Impact Concomitant use with a moderate to strong CYP3A inducer decreases aficamten exposure, which may reduce MYQORZO effectiveness [see Clinical Pharmacology (12.3) ] . The risk of heart failure due to systolic dysfunction may increase with discontinuation of these inducers. Prevention or Management In patients who intend to discontinue a moderate to strong CYP3A Inducer: Reduce dose of MYQORZO (20 mg to 10 mg; 15 mg to 5 mg; 10 mg to 5 mg) or continue 5 mg [see Dosage and Administration (2.3) ].

Contraindications

4 CONTRAINDICATIONS MYQORZO is contraindicated with concomitant use of rifampin [see Warnings and Precautions (5.3) and Drug Interactions (7.1) ] . Rifampin ( 4 )

Safety data

Reported adverse events (FAERS)

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Source: FDA Adverse Event Reporting System via openFDA

Liver injury (LiverTox)

E

Likelihood score E: Unlikely cause of clinically apparent liver injury.

Aficamten is a small molecule inhibitor of cardiac myosin that is currently used to improve symptoms and functional capacity in patients with symptomatic obstructive hypertrophic cardiomyopathy. Aficamten is associated with a low rate of serum aminotransferase elevations during therapy but has not been implicated in cases of clinically apparent liver injury.

ABCDEA: well known cause; E: unlikely cause. [HD]: high doses only.

Source: LiverTox: Aficamten (NIDDK, public domain)Chapter updated Jan 10, 2026

Pregnancy and lactation

Pregnancy

8.1 Pregnancy Risk Summary There are no available data on the use of MYQORZO during pregnancy to evaluate for a drug-associated risk of major birth defects, miscarriage, or other adverse maternal or fetal outcomes. The underlying maternal condition during pregnancy poses a risk to the mother and fetus (see Clinical Considerations ) . In embryo-fetal and pre- and postnatal development studies, when pregnant rats were administered aficamten during the period of organogenesis, aficamten increased the incidence of structural malformations at exposures ≥4-times the maximum recommended human dose (MRHD) of 20 mg based on free area under the concentration curve (AUC) .

No adverse effects on development were seen at 3-times the MRHD exposure (see Data ) . The background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defects, loss, and other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively. There is a pregnancy safety study for MYQORZO.

If MYQORZO is administered during pregnancy, or if a patient becomes pregnant while receiving MYQORZO or within 3 weeks after the last dose of MYQORZO, healthcare providers should report MYQORZO exposure by contacting Cytokinetics, Inc. at 1-833-633-2986. Clinical Considerations Disease-Associated Maternal and Embryo-Fetal Risk Obstructive HCM in pregnancy has been associated with increased risk for preterm birth.

Data Animal Data Aficamten given to pregnant rats (2, 6 and 9 mg/kg/day) during the period of organogenesis was associated with increased external fetal malformations (kinked tail) at aficamten exposures 5-times the clinical exposures at the MRHD based on free AUC, with uncertain human relevance. Increased post-implantation loss (early and late resorptions) and decreased mean fetal body weight occurred in the presence of significant maternal toxicity at exposures 5-times the clinical exposures at the MRHD. No adverse effects on embryofetal development were observed at 6 mg/kg/day, representing 3-times the clinical exposure at the MRHD.

Pregnant rabbits given aficamten (5, 10 and 20/15 mg/kg/day) during the period of embryofetal organogenesis showed a numerical increase in post-implantation loss (late resorptions) and fetuses with cardiac malformations at 10 mg/kg/day. However, no increase in malformations was observed at the high dose of 20/15 mg/kg/day, a dose that caused significant…

Breastfeeding (LactMed)

No information is available on the clinical use of aficamten during breastfeeding. Because the drug is 90% bound to plasma proteins, amounts in milk are likely to be low. If a mother requires aficamten, it is not a reason to discontinue breastfeeding.

Source: LactMed: Aficamten (NICHD, public domain)Revised Feb 15, 2026

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