SS-31 (Elamipretide)

Grade A applies only to the approved Forzinity product, which received FDA accelerated approval for Barth syndrome based on a strength change in about 10 patients; randomized trials in other conditions missed their main goals.

Strengths: 10, 30, 50 mg
Also known as: Elamipretide, MTP-131, Bendavia (earlier name), Forzinity (approved brand)
Molecule: 4-amino-acid mitochondria-targeted peptide
Formula: C32H49N9O5
Mol. weight: 639.80 g/mol
CAS: 736992-21-5
Sequence: D-Arg-Dmt-Lys-Phe-NH2 (Dmt = 2′,6′-dimethyl-L-tyrosine)

Origin

Developed as a mitochondria-targeted tetrapeptide (earlier called Bendavia and MTP-131) and brought to market by Stealth BioTherapeutics as Forzinity.

How it works

Accumulates at the inner mitochondrial membrane and binds cardiolipin, a lipid that holds respiratory-chain proteins together. Early papers described it as an antioxidant; newer work says it changes the membrane's electrical surface and helps cardiolipin-dependent complexes assemble. In Barth syndrome, a gene defect impairs the enzyme that remodels cardiolipin.

What the research shows

In Barth syndrome (TAZPOWER, 12 males), the randomized phase missed its primary endpoints, but knee-extensor strength rose in the open-label extension, which FDA accepted for accelerated approval. A 218-adult phase 3 trial in primary mitochondrial myopathy missed both primary endpoints, with a possible signal in a genetic subgroup. A phase 2 trial in dry AMD slowed photoreceptor loss, and a phase 3 trial is under way; trials in heart failure and heart attack were negative. There are no human data in healthy aging.

Key studies

TAZPOWER (Barth syndrome), label data Primary endpoints not met in 12 males; strength rose in the open-label extension (basis of approval).
Karaa et al., Neurology 2023 (MMPOWER-3) 218 adults with mitochondrial myopathy: both primary endpoints failed.
ReCLAIM-2 phase 2 (dry AMD) 176 patients: photoreceptor-loss progression slowed 43% vs placebo.
Butler et al., J Card Fail 2020 (PROGRESS-HF) 71 heart-failure patients: no change in heart function vs placebo.

Safety findings

Injection-site reactions were nearly universal in the Barth trial (redness in 100%, pain 75%) and were the most common event in other trials. The label warns of serious allergic reactions, from minutes to months after starting, and eosinophil counts rose in longer studies. Kidney impairment raises exposure; there are no data in pregnancy or adults 65 and older.

Regulatory status

The brand drug Forzinity received FDA accelerated approval on September 19, 2025, only to improve muscle strength in Barth syndrome in patients weighing at least 30 kg, with a confirmatory trial required; approval does not cover research vials. As an approved-drug component it has a 503A eligibility route; it is not on FDA's safety-risk list. Not named on the 2026 WADA list, and US approval likely takes it out of S0.

Catalog notes

Available in 10, 30 and 50 mg, all with certificates tested August 17, 2026: SS31-10-0803 (99.77%, COA7584), SS31-30-0803 (99.78%, COA7579) and SS31-50-0803 (99.75%, COA7590). Follow the storage stated on the label and certificate.

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