# SS-31

> Evidence tier S — Approved · Longevity & Immune · reviewed 2026-11-08
> Source page: https://peptidemeta.com/p/ss-31/

Also known as: Elamipretide, Forzinity, MTP-131, Bendavia

## Quick answers

**What is SS-31?**

A mitochondria-targeted tetrapeptide (elamipretide, brand Forzinity) that binds cardiolipin in the inner mitochondrial membrane.

**How strong is the evidence for SS-31?**

Tier S (approved) on the peptidemeta evidence scale. FDA granted accelerated approval in September 2025 (Forzinity) to improve muscle strength in Barth syndrome. Continued approval depends on a confirmatory randomized trial.

**Is SS-31 FDA-approved?**

Yes. The FDA approved SS-31 (Forzinity) in 2025. Accelerated approval to improve muscle strength in adults and children with Barth syndrome who weigh at least 30 kg.

**Is SS-31 banned in sport?**

No. SS-31 is not on the World Anti-Doping Agency Prohibited List.

**How does SS-31 work?**

SS-31 (Elamipretide) is a cell-permeable aromatic-cationic tetrapeptide (D-Arg-Dmt-Lys-Phe-NH2) that concentrates 1000-fold in the inner mitochondrial membrane. It binds cardiolipin, stabilizing its interaction with cytochrome c and restoring electron transport chain efficiency.

**What is known about the safety of SS-31?**

FDA-approved (Forzinity, accelerated approval 2025) for Barth syndrome; continued approval depends on a confirmatory randomized trial. Per the FDA label, the most common adverse reactions are injection site reactions.

## Key facts

- **Evidence tier:** S (Approved)
- **FDA:** approved 2025 (Forzinity)
- **WADA:** not on the Prohibited List
- **Peptide:** yes
- **Sequence:** [D-Arg][Dmt]KF[NH2] (4 residues)
- **Formula:** C32H49N9O5
- **Molecular weight:** 639.8 g/mol
- **Routes studied:** Subcutaneous, Intramuscular

## Overview

A mitochondria-targeted tetrapeptide (elamipretide, brand Forzinity) that binds cardiolipin in the inner mitochondrial membrane. FDA granted it accelerated approval in September 2025 to improve muscle strength in Barth syndrome.

## Mechanism

SS-31 (Elamipretide) is a cell-permeable aromatic-cationic tetrapeptide (D-Arg-Dmt-Lys-Phe-NH2) that concentrates 1000-fold in the inner mitochondrial membrane. It binds cardiolipin, stabilizing its interaction with cytochrome c and restoring electron transport chain efficiency. This reduces electron leak and reactive oxygen species production at the source.

## Effects reported in research

_Reported outcomes, not promises; see the evidence tier._

- Restored mitochondrial electron transport
- Reduced reactive oxygen species production
- Improved cardiac function in heart failure
- Protected against age-related mitochondrial decline

## Safety & unknowns

FDA-approved (Forzinity, accelerated approval 2025) for Barth syndrome; continued approval depends on a confirmatory randomized trial. Per the FDA label, the most common adverse reactions are injection site reactions. Use outside Barth syndrome is investigational.

## Studies

- Thompson WR, Manuel R, Abbruscato A, et al. (2024). *Long-term efficacy and safety of elamipretide in patients with Barth syndrome: 168-week open-label extension results of TAZPOWER*. Genetics in Medicine. Clinical trial. https://pubmed.ncbi.nlm.nih.gov/38602181/
  Open-label extension of the TAZPOWER trial reporting sustained tolerability and improvements in functional assessments and cardiac function with elamipretide in Barth syndrome over 168 weeks.
- Karaa A, Bertini E, Carelli V, et al. (2023). *Efficacy and Safety of Elamipretide in Individuals With Primary Mitochondrial Myopathy: The MMPOWER-3 Randomized Clinical Trial*. Neurology. Clinical trial. https://pubmed.ncbi.nlm.nih.gov/37268435/
  Phase 3 randomized placebo-controlled trial in primary mitochondrial myopathy in which elamipretide did not improve the primary endpoints (6-minute walk distance and fatigue scores) versus placebo.

## Status sources

- [FDA approval letter, NDA 215244 (Forzinity), 19 Sep 2025](https://www.accessdata.fda.gov/drugsatfda_docs/appletter/2025/215244Orig1s000ltr.pdf)
- [Forzinity prescribing information (FDA label)](https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/215244s000lbl.pdf)
- [PubChem CID 11764719 (elamipretide)](https://pubchem.ncbi.nlm.nih.gov/compound/11764719)
- [WADA 2026 Prohibited List (not named; S0 does not apply to an approved drug)](https://www.wada-ama.org/sites/default/files/2025-09/2026list_en_final_clean_september_2025.pdf)

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Educational reference only — not medical advice. No dosing information is published. Tiers rate the strength of published evidence, not effectiveness or safety.