Forzinity

Forzinity is used to improve muscle strength in adults and children with Barth syndrome who weigh at least 30kg. Forzinity is a subcutaneous injection administered daily.

Forzinity (elamipretide) gained FDA approval on September 19, 2025, under the accelerated approval designation based on clinical trials showing significant improvement in knee extensor muscle strength.

• Forzinity is the first FDA-approved therapy specifically for Barth Syndrome.
• Continued approval may be contingent upon a continued benefit being shown in confirmatory clinical trials.

Do not use Forzinity:

• If you are allergic to Forzinity, elamipretide, or any of the inactive ingredients in the injection
• In neonates or premature babies. Forzinity is not approved for this population.

Before using Forzinity, tell your healthcare provider about all your medical conditions, including if you:

• Have allergies
• Are pregnant or intending to become pregnant
• Are breast feeding or intending to breastfeed.

Pregnancy

Barth Syndrome mainly affects males (X-linked genetic condition), so pregnancy use is unlikely, and there is no pregnancy data available for Forzinity.

• Animal studies showed no developmental problems at any dose tested.
• Benzyl alcohol (preservative) breaks down quickly in pregnant women, so minimal fetal exposure is expected.

Breastfeeding

Barth Syndrome mainly affects males (X-linked genetic condition), so breastfeeding use is unlikely, and there is no breastfeeding data available for Forzinity.

• Benzyl alcohol (preservative) breaks down quickly in nursing mothers, so minimal infant exposure is expected.

Administer Forzinity once a day by subcutaneous injection (an injection under the skin).

• Administer at the same time each day
• Your healthcare provider will train you on safe preparation and injection of Forzinity. You should also read the Instructions for Use
• Forzinity comes as a multi-dose vial that contains several doses
• Use a new disposable syringe/needle each time
• Forzinity is injected in the abdomen (at least 2 inches from the navel) or outer thigh.
• Rotate the injection site daily, according to the Instructions for Use.
• Do not inject where the skin is tender, bruised, red, or hard. Avoid injecting into scars or stretch marks.

Before First Use:

• Let the vial reach room temperature (10+ minutes).
• Write the discard date on the vial (8 days from opening).
• Check the tamper seal is intact.

Missed Dose

If a dose is missed, skip the dose and take the next dose of Forzinity at the scheduled time. Do not take a double dose of Forzinity.

Common Side Effects

The most common side effects of Forzinity are injection site reactions, with symptoms such as:

• Redness and pain
• Swelling (induration)
• Itching (pruritus)
• Bruising
• Hives (urticaria).

These can be treated with antihistamines or topical corticosteroids.

Serious Side Effects

Forzinity may cause the following serious side effects.

Allergic Reactions

Hypersensitivity reactions, including serious allergic reactions requiring emergency medical intervention, havebeen reported in patients receiving Forzinity. These reactions have included skin manifestations such asa skin rash, facial swelling, as well as respiratory symptoms, including a cough. Reactions may occur within minutes to months after treatment initiation. Stop using Forzinity and seek immediate medical attention.

Risk of Benzyl Alcohol Toxicity in Neonates

Forzinity injection is not approved for use in neonates. Serious adverse reactions, including fatal reactions, of newonset or worsening metabolic acidosis that progressed to neurotoxicity, and in some cases, gasping syndrome,have been reported in low-birth-weight neonates (less than 2,500 grams) and preterm neonates (gestational ageless than 34 weeks) who received benzyl alcohol (BA)-containing drugs intravenously. Forzinity is only given subcutaneously.

Notes:

These are not all the possible side effects of Forzinity. Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Forzinity (elamipretide) works through a unique mitochondrial targeting mechanism that addresses the root cause of muscle weakness in Barth syndrome. It binds to cardiolipin, a critical lipid in mitochondria, specifically targeting the inner mitochondrial membrane to facilitate repair. By improving mitochondrial structure and function, Forzinity restores cellular energy production in muscle cells, ultimately enhancing muscle strength. This targeted approach directly treats the underlying mitochondrial dysfunction characteristic of Barth syndrome.

Forzinity injection belongs to the drug class called mitochondrial cardiolipin binder.

Dose of Forzinity for Barth Syndrome

• Adults and children ≥30kg: 40 mg subcutaneously once daily
• Kidney impairment (eGFR <30 mL/min, not on dialysis): 20 mg subcutaneously once daily
• Dialysis patients: Insufficient data, consult a physician.

Store refrigerated at 2°C to 8°C (36°F to 46°F). Do not freeze.

Following the first dose, the opened vial can be stored either refrigerated at 2°C to 8°C (36°F to 46°F) or at room temperature between 20°C and 25°C (68°F to 77°F). Discard vials 8 days after first opening.

Forzinity is manufactured for Stealth BioTherapeutics Inc., Needham, MA 02494.