Mitochondrial Disorders

What the evidence shows for elamipretide in Barth syndrome and mitochondrial myopathy, and for the mitochondria-linked peptides MOTS-c and humanin, with the FDA accelerated approval explained.

Content last updated October 22, 2026. This page has not been medically reviewed.

Quick answer

Mitochondrial disorders are rare genetic conditions in which the cell's energy machinery does not work properly. One peptide-based medicine, elamipretide, has a US approval for one of them, Barth syndrome, under a conditional route called accelerated approval. In a second, broader mitochondrial condition it did not beat placebo in a large trial. Two mitochondria-linked peptides popular online, MOTS-c and humanin, have lab and animal data and no approved use. A peptide helping one mitochondrial disease does not mean peptides treat mitochondrial problems in general, and it says nothing about energy, aging or athletic claims.

Evidence labels used here. Approved medicine: a regulator approved it for a named use. Mixed: one trial positive on some measures, another negative. Preclinical: cells or animals only. Insufficient evidence: too little human data. A lab marker such as a blood or cell measurement is a biomarker. Walking distance, strength and fatigue are clinical outcomes.

For general background, see Mitochondrial Signaling and Mitochondrial-Derived Peptides and Mitochondria and Oxidative Stress in Aging.

Elamipretide: identity and approval

Elamipretide is a tetrapeptide (four amino acids) that is described as binding cardiolipin, a fat found in the inner mitochondrial membrane. [1] Names seen in the literature for the same molecule include SS-31, MTP-131 and Bendavia. [1] The US brand is Forzinity. [2]

Barth syndrome is an extremely rare, potentially fatal X-linked mitochondrial disease that can affect the heart, blood cells, muscles and growth. [3]

FDA label (United States). Per the DailyMed label (initial US approval 2025, read 2026-10-22), Forzinity is indicated to improve muscle strength in adult and pediatric patients with Barth syndrome who weigh at least 30 kg. [2] It was approved under accelerated approval based on improvement in knee extensor muscle strength, an "intermediate clinical endpoint", and continued approval may depend on a confirmatory trial. [2] Accelerated approval means a medicine can be approved sooner on a substitute measure while benefit on how people feel and function is still being confirmed.

What the trials showed

Study	Molecule and people	Design and length	Main result	Funding and limits
TAZPOWER randomized phase (per FDA label)	Elamipretide in 12 people with genetically confirmed Barth syndrome, aged 12 and older and at least 30 kg [2]	Randomized, double-blind, placebo-controlled crossover; 12 weeks [2]	Not superior to placebo on the primary endpoints (6-minute walk and a fatigue score); strength gains were not seen in this phase [2]	Tiny group.
TAZPOWER extension (2024)	10 people entered; 8 reached week 168 [4]	Open-label extension after a randomized phase that the paper describes as 28 weeks (the label describes 12 weeks of treatment in a crossover) [4][2]	Walking distance improved from extension baseline, and strength increases were seen during the extension; injection-site reactions were the most common adverse event [4][2]	No placebo group in the extension. Authors include company employees and funded researchers. [4]
MMPOWER-3 (2023), a different condition: primary mitochondrial myopathy	218 adults with genetically confirmed disease (109 per group) [5]	Phase 3, randomized, double-blind, placebo-controlled; 24 weeks [5]	Did not meet its primary endpoints (walking distance, fatigue); well tolerated [5]	Investigators reported grants and consulting payments from the sponsor, Stealth. [5]

Plain reading: mixed. The approval in Barth syndrome rests on a very small randomized phase that missed its main goals and an uncontrolled extension, which is why it is conditional. [2] The bigger mitochondrial myopathy trial was negative. [5] Strength increases seen after the randomized phase are descriptive and have no placebo comparison. [2]

Safety (label). The most common adverse reactions are injection-site reactions. [2] The label notes serious allergic reactions, and it is not approved for neonates because the product contains benzyl alcohol. [2] Whether to use it, and for whom, is a specialist decision. Please do not stop or change any medicine without your prescriber.

MOTS-c and humanin

MOTS-c and humanin are small peptides encoded in mitochondrial DNA. [6] Reviews describe that treating rodents with humanin or MOTS-c can improve insulin sensitivity, and that it "remains to be fully determined" whether this can become a therapy. [6] In people, one small exercise study found that endurance exercise raised circulating humanin, and the authors said blood levels were not linked to fitness. [7] That measures the body's own levels. It does not test giving the peptide.

On the FDA bulk-compounding page (content current as of 04/22/2026, read 2026-10-22), MOTS-c is listed in the section "nominated but withdrawn", and FDA states it has not identified any human exposure data on drug products containing MOTS-c by any route. [8] Evidence label: preclinical for treatment; proper evidence not found for human treatment trials. For humanin, no regulatory page was read for this page, so its status is not verified.

Frequently asked questions

Is there an approved peptide for mitochondrial disease?

One: elamipretide (Forzinity) has US accelerated approval for Barth syndrome. [2]

Did elamipretide work for other mitochondrial diseases?

In the large MMPOWER-3 trial of primary mitochondrial myopathy it did not improve walking distance or fatigue versus placebo. [5]

What does accelerated approval mean?

Approval on an intermediate measure, with continued approval depending on a confirmatory trial. [2]

Is MOTS-c proven to raise energy or slow aging?

No. The evidence found is in rodents and cells, plus human blood-level studies. [6][7]

Is SS-31 a different drug from elamipretide?

SS-31 is one of the names used in the literature for elamipretide. [1]

More details: evidence, limits and cautions

The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.

Safety and next steps

Suspected mitochondrial disease is diagnosed and managed by specialists, usually through genetic centers. For how claims are checked, see How to Evaluate Peptide Claims and Clinic Marketing.

References

Elamipretide: A Review of Its Structure, Mechanism of Action, and Therapeutic Potential. Int J Mol Sci 2025. PubMed abstract read 2026-10-22.
FORZINITY (elamipretide hydrochloride) injection, prescribing information (DailyMed, Stealth BioTherapeutics; version published 2025-12-12). Read 2026-10-22.
Elamipretide in the Management of Barth Syndrome: Current Evidence and a Case Report. Mol Genet Metab 2025. PubMed abstract read 2026-10-22.
Long-term efficacy and safety of elamipretide in patients with Barth syndrome: 168-week open-label extension results of TAZPOWER. Genet Med 2024. PubMed abstract read 2026-10-22.
Efficacy and Safety of Elamipretide in Individuals With Primary Mitochondrial Myopathy: The MMPOWER-3 Randomized Clinical Trial. Neurology 2023. PubMed abstract read 2026-10-22.
Mitochondrial-derived peptides in energy metabolism. Am J Physiol Endocrinol Metab 2020. PubMed abstract read 2026-10-22.
Acute endurance exercise stimulates circulating levels of mitochondrial-derived peptides in humans. J Appl Physiol 2021. PubMed abstract read 2026-10-22.
FDA, Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks (page content current as of 04/22/2026). Read 2026-10-22.

Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.