SS-31 and MOTS-c blend
This pairing joins one of the few 'mitochondrial' peptides with a real FDA approval to one that has never been given to people as a treatment. The approval is narrow, the trials outside it mostly failed, and the combination has never been tested.
As sold, one vial: SS-31 10 mg, MOTS-c 10 mg. Statuses as of October 3, 2026. Reviewed by the Grey Peptides Editorial Board. Nothing here is a recommendation or a dose, and no seller is named or linked.
Each component at a glance
From our encyclopedia and FDA's July 2026 Pharmacy Compounding Advisory Committee record. Evidence grades follow the rubric on our methodology page.
| Component | Evidence | FDA status | PCAC, July 2026 | WADA 2026 | WADA 2027 | Interactions |
|---|---|---|---|---|---|---|
| SS-31 | High | FDA Approved | Not voted on | Not on the List | Not on the List | None found in the literature |
| MOTS-c | Low | Research Chemical | Recommended (7-5, July 23, 2026); FDA has not acted | Prohibited (S4.4.1) | Prohibited (S4.4.1) | Not yet reviewed |
What one vial contains: the ratio arithmetic
The vial holds 20 mg in total. Whatever volume of water is added and however much is drawn, every draw carries the components in the same proportions. The table expresses each as a share of the vial, as a multiple of the smallest component (SS-31), and as a concentration if the whole vial were dissolved in 2 mL or 3 mL of water. These are arithmetic illustrations of what is in the vial, not suggested volumes or doses.
| Component | In the vial | Share | × SS-31 | In 2 mL | In 3 mL |
|---|---|---|---|---|---|
| SS-31 | 10 mg | 50.0% | 1 | 5 mg/mL | 3.33 mg/mL |
| MOTS-c | 10 mg | 50.0% | 1 | 5 mg/mL | 3.33 mg/mL |
The Blend & Stack Calculator runs the same arithmetic for any volume and draw, with this composition as a preset (SS-31 and MOTS-c, 20 mg (10/10), example composition).
SS-31 on its own
SS-31, elamipretide, is a designed peptide that binds cardiolipin, a lipid of the inner mitochondrial membrane (laboratory and animal study)1. FDA granted it accelerated approval on September 19, 2025 as Forzinity, for muscle strength in adults and children with Barth syndrome weighing at least 30 kg2. That rests on a small programme: a 12-person crossover trial whose crossover portion missed its primary endpoint, followed by an open-label extension with improvements in walking, strength and fatigue (randomised trial and extension)34.
Outside Barth syndrome, results were disappointing: in 218 adults with primary mitochondrial myopathy it did not improve the six-minute walk or fatigue at 24 weeks (randomised trial)5; in 71 people with heart failure, the primary heart-volume measure did not differ from placebo (randomised trial)6; and in dry macular degeneration the primary endpoints were missed, with 17% stopping for injection-site reactions against about 9% on placebo (randomised trial)7.
MOTS-c on its own
MOTS-c is a 16-amino-acid peptide encoded in mitochondrial DNA, named in 2015 in mouse work showing it regulates insulin sensitivity and metabolism (animal study)8. In mice it improved physical performance at several ages (animal study)9. Human evidence is observational, such as a genetic variant linked to type 2 diabetes in men across 27,527 people (genetic association)10. No trial has given MOTS-c to people as a treatment, and it is not approved2.
Why the pair has no trial
The rationale offered for the stack is that both act on mitochondria, so together they should do more. But they act in unrelated ways: SS-31 binds a membrane lipid inside mitochondria1, while MOTS-c is a signal that moves to the nucleus under stress and changes gene expression8. Sharing a label does not make effects add up. We found no study of the two together in people or animals, and only one of them has ever been tested as a treatment in humans.
What the ratio means
With 10 mg of each in our example, as the table above shows, every draw holds equal milligrams of both. The trials of SS-31 used daily injections at a fixed dose under medical supervision5; MOTS-c has no human dose at all. A combined vial ties an unstudied peptide to a studied one at an arbitrary ratio. Our Blend Calculator shows the arithmetic; it describes content, not a dose.
Side effects and interactions
SS-31's most visible problem in long trials was injection-site reactions, which led 17% to stop in the macular degeneration trial7. MOTS-c's effects on blood sugar in mice8 mean anyone on glucose-lowering drugs should be cautious, though no human data exist. Neither peptide's interactions have been reviewed in our matrix as fully studied2.
Regulatory status in the United States
SS-31 is approved only as Forzinity, for Barth syndrome; a research vial is not that product. MOTS-c is not approved for any use2.
For tested athletes
WADA names MOTS-c under S4.4.1, metabolic modulators, so any product containing it is prohibited at all times; SS-31 is not listed2. Our MOTS-c vs SS-31 comparison covers the two in more depth.
What to check before anything else
If you have Barth syndrome, the approved product exists and a specialist can prescribe it. For energy or ageing, neither peptide has human evidence of benefit, and the one human-tested component mostly failed outside its rare disease. Ask for a certificate that quantifies each peptide separately.
Sources
- Birk, A. V., et al. (2013). The mitochondrial-targeted compound SS-31 re-energizes ischemic mitochondria by interacting with cardiolipin. J Am Soc Nephrol, 24. PubMed 23813215 ↗
- Grey Peptides encyclopedia entries for SS-31 (Forzinity accelerated approval, September 19, 2025) and MOTS-c (not approved; WADA S4.4.1), including interaction coverage. Read October 3, 2026.
- Reid Thompson, W., et al. (2021). 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, 23. PubMed 33077895 ↗
- Shirley, M. (2026). Elamipretide: First Approval. Drugs, 86. PubMed 41335372 ↗
- Karaa, A., et al. (2023). Efficacy and Safety of Elamipretide in Individuals With Primary Mitochondrial Myopathy: The MMPOWER-3 Randomized Clinical Trial. Neurology, 101. PubMed 37268435 ↗
- Butler, J., et al. (2020). Effects of Elamipretide on Left Ventricular Function in Patients With Heart Failure With Reduced Ejection Fraction: The PROGRESS-HF Phase 2 Trial. J Card Fail, 26. PubMed 32068002 ↗
- Ehlers, J. P., et al. (2025). ReCLAIM-2: A Randomized Phase II Clinical Trial Evaluating Elamipretide in Age-related Macular Degeneration, Geographic Atrophy Growth, Visual Function, and Ellipsoid Zone Preservation. Ophthalmol Sci, 5. PubMed 39605874 ↗
- Lee, C., et al. (2015). The mitochondrial-derived peptide MOTS-c promotes metabolic homeostasis and reduces obesity and insulin resistance. Cell Metab, 21. PubMed 25738459 ↗
- Reynolds, J. C., et al. (2021). MOTS-c is an exercise-induced mitochondrial-encoded regulator of age-dependent physical decline and muscle homeostasis. Nat Commun, 12. PubMed 33473109 ↗
- Zempo, H., et al. (2021). A pro-diabetogenic mtDNA polymorphism in the mitochondrial-derived peptide, MOTS-c. Aging (Albany NY), 13. PubMed 33468709 ↗
Related: the blends and stacks hub, the Name Decoder, the COA Decoder and the Interaction Matrix. Last updated October 3, 2026.