SS-31

SS-31 (Elamipretide; also known as MTP-131) is a modified peptide studied for its effects on cardiovascular health and aging. Mitochondria-targeted tetrapeptide that binds cardiolipin. FDA-approved (accelerated) as Forzinity for Barth syndrome; investigational for all other uses.

SS-31, known by its generic name elamipretide, is a synthetic mitochondria-targeted tetrapeptide (D-Arg-Dmt-Lys-Phe-NH2) first described as a Szeto-Schiller peptide and later developed under the code MTP-131. It enters cells and concentrates on the inner mitochondrial membrane, where it binds cardiolipin, a lipid that anchors the electron transport chain; this binding is proposed to stabilize mitochondrial energy production and reduce oxidative stress. In September 2025 the US Food and Drug Administration (FDA) granted accelerated approval to elamipretide, sold as Forzinity, to improve muscle strength in people with Barth syndrome who weigh at least 30 kg, with continued approval tied to a confirmatory trial.

Overview

All other uses, including heart failure, mitochondrial myopathy, age-related decline and the research-peptide market, remain investigational.

Elamipretide is not approved by the World Anti-Doping Agency (WADA) and is treated as prohibited by WADA.

Mechanism of action

Binds cardiolipin in mitochondria, proposed to stabilize energy production and reduce oxidative stress. Has accelerated FDA approval to improve muscle strength in Barth syndrome. Investigational for other uses.

Reported effects

Effects reported in the literature and from preclinical models include:

• Elamipretide was granted accelerated approval in the USA in September 2025 to improve muscle strength in adult and pediatric patients with Barth syndrome weighing at least 30 kg. ^[4] FDA approved
• In early-phase clinical trials, elamipretide caused no severe adverse events and improved cardiac hemodynamics at the highest doses. ^[2] Phase I
• Elamipretide increased left ventricular ejection fraction in dog models of heart failure with reduced ejection fraction and prevented left ventricular remodeling in rats. ^[2] Preclinical
• Elamipretide binds cardiolipin in the inner mitochondrial membrane, stabilizing cristae structure, reducing oxidative stress and enhancing ATP production. ^[3] Preclinical
• Elamipretide showed protective and restorative effects in preclinical models of heart failure, neurodegeneration, ischemia-reperfusion injury, metabolic syndromes, and muscle atrophy and weakness. ^[3] Preclinical
• SS-31 showed neuroprotective effects against mitochondrial dysfunction in preclinical studies of postoperative cognitive dysfunction. ^[1] Preclinical

Evidence grades: FDA approvedApproved (non-US)Phase IIIPhase IIPhase IPreclinicalAnecdotal

Dosage and administration

FDA

• approved dose (Forzinity, Barth syndrome, patients 30 kg and over): 40 mg by subcutaneous injection once daily

General

• Severe kidney impairment (eGFR under 30 mL/min, not on dialysis): 20 mg subcutaneously once daily
• No established or approved dose for any other use; research-market dosing has not been validated in controlled trials

Natty status

SS-31 is classified as not natty. It appears on the WADA prohibited list and is banned by major natural bodybuilding federations.^[5] Use of this compound places the athlete in the enhanced category rather than the natural category in competitive contexts.

Research

The peptide has been the subject of 5 studies and reference works collected on this site. Additional bibliography is in § External links below.

Related compounds

Other peptides in this catalogue with overlapping mechanisms or status:

Frequently asked questions

What is SS-31?

Mitochondria-targeted tetrapeptide that binds cardiolipin. FDA-approved (accelerated) as Forzinity for Barth syndrome; investigational for all other uses.

What is SS-31 used for?

SS-31 (Elamipretide) is used to improve muscle strength in Barth syndrome, the one use with accelerated US approval. It is also used for heart failure, age-related decline and other conditions tied to weak cell energy, which remain under study.

How does SS-31 work?

A small lab-made peptide, given as a daily injection under the skin. It collects inside mitochondria, the parts of a cell that make energy, and binds a fat there called cardiolipin. This is thought to steady energy production and lower oxidative stress, a kind of cell wear from harmful oxygen by-products.

Is SS-31 natty?

No. SS-31 is classified as not natty. It is prohibited by WADA and banned by most natural bodybuilding federations. Use places an athlete in the enhanced category.

Is SS-31 banned by WADA?

Yes. SS-31 is prohibited by the World Anti-Doping Agency (WADA), so drug-tested athletes cannot use it. Check the current WADA Prohibited List before competing.

How is SS-31 administered?

SS-31 is typically administered via: subcutaneous injection. Dosage and administration protocols vary; see the Dosage section for details.

References

1. ^ Targeting Mitochondria for Postoperative Cognitive Dysfunction: From Mechanisms to Therapeutics. Recent review
2. ^ a b Targeting mitochondrial dysfunction with elamipretide. Recent review
3. ^ a b Elamipretide: A Review of Its Structure, Mechanism of Action, and Therapeutic Potential. Recent review
4. ^ Elamipretide: First Approval. Recent review
5. ^ a b World Anti-Doping Agency. (2026). Prohibited List 2026.

External links

• The Role of Oxidative Stress in Heart Failure: Mechanisms and Therapeutic Targets.
• 10mg SS-31 — commercial