Introducing the first and only prescription medication approved by the FDA to treat Barth syndrome

FORZINITY™ (elamipretide) is a once-daily injection indicated to improve muscle strength in individuals weighing at least 30 kg (~66 lbs) who are affected by Barth syndrome.¹

This indication is approved under accelerated approval based on an improvement in knee extensor muscle strength, an intermediate clinical endpoint. Continued approval for this indication may be contingent upon verification and description of clinical benefit in a confirmatory trial(s).¹

First-in-class mechanism of action²

FORZINITY is a mitochondrial cardiolipin binder that addresses the underlying issue by working directly inside the inner mitochondrial membrane to improve mitochondrial structure and function¹

Strengthened physical performance¹*

After 168 weeks on FORZINITY, 8 affected individuals showed a median 51% improvement in strength in the muscles that help straighten the knee^†

Well-characterized safety profile¹*

The most common side effects with FORZINITY are injection site reactions, which are generally mild to moderate

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*These results are from a clinical study in affected individuals 12 years and older with genetically confirmed Barth syndrome. In the study, 12 affected individuals received FORZINITY or placebo once a day for 12 weeks before crossing over to receive the opposite treatment after undergoing a 4-week washout period. Upon completion of the crossover aspect of the trial, the participants could enter the open-label extension (OLE) period where initially 10 individuals received FORZINITY. By the end of the OLE, 8 participants were receiving treatment that lasted up to 192 weeks.^1,3

^†A median increase of 63 newtons of strength from the pre-dose baseline visit.¹

References: 1. Forzinity Full Prescribing Information. Needham, MA. Stealth BioTherapeutics, Inc.; 11/2025. 2. United States Adopted Name (USAN). Accessed December 11, 2025. https://searchusan.ama-assn.org/usan/documentDownload?uri=/unstructured/binary/usan/elamipretide.pdf 3. Thompson WR, Hornby B, Manuel R, et al. A phase 2/3 randomized clinical trial followed by an open-label extension to evaluate the effectiveness of elamipretide in Barth syndrome, a genetic disorder of mitochondrial cardiolipin metabolism. Genet Med. 2021;23(3):471–478. doi:10.1038/s41436-020-01006-8

IMPORTANT SAFETY INFORMATION

What should I tell my doctor before taking FORZINITY™?

Before taking FORZINITY tell your doctor about all of the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements. You should also tell your doctor if you have or had:

any allergies
kidney problems

What are the possible side effects of FORZINITY?

Injection site reactions: The most common side-effects or adverse reactions with FORZINITY are redness, swelling, pain, itching, bruising, or hives at the site of injection. These adverse reactions are referred to as injection site reactions.
Allergic reactions. FORZINITY may cause allergic reactions, such as rash, small, raised skin bumps known as papular lesions, inflammation of the skin or eczematous dermatitis, as well as respiratory symptoms including cough. Stop using FORZINITY and get medical help right away if you develop any of the following symptoms of a severe allergic reaction:: swelling of your face, lips, mouth, or tongue; trouble breathing or airway constriction; wheezing; dizziness or fainting; fast heartbeat or pounding in your chest; sweating

These are NOT all of 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 or www.fda.gov/medwatch.

What is FORZINITY used for?

FORZINITY is a prescription medicine used to improve muscle strength in adult and pediatric individuals living with Barth syndrome weighing at least 30 kg. The safety and effectiveness of FORZINITY have not been established in pediatric individuals weighing less than 30 kg.

The recommended dosage of FORZINITY in most affected individuals weighing at least 30 kg is 40 mg subcutaneously once daily. For individuals with reduced renal function, please have your doctor refer to the Prescribing Information.

The risk information provided here is not comprehensive. To learn more, talk with your doctor and read the full Prescribing Information.

Introducing the first and only prescription medication approved by the FDA to treat Barth syndrome

First-in-class mechanism of action2

Strengthened physical performance1*

Well-characterized safety profile1*