SS-31, now marketed as elamipretide, is not a generic research-peptide story. FDA granted accelerated approval in 2025 for one defined product, Forzinity, to improve muscle strength in people with Barth syndrome who weigh at least 30 kg. That is not approval for fatigue, athletic performance, longevity, or a powder sold under an SS-31 label.
Reviewed by the PepGuard team · Last reviewed Jul 28, 2026
Synthetic tetrapeptide: D-Arg-2,6-dimethyl-Tyr-Lys-Phe-NH2 · also sold as SS-31, MTP-131, Bendavia, Forzinity
Forzinity is the FDA-approved elamipretide product. Its indication is to improve muscle strength in adults and pediatric patients weighing at least 30 kg with Barth syndrome, a rare genetic disorder. It was granted accelerated approval using knee-extensor strength as an intermediate endpoint.
The label is unusually transparent about the evidence size: the placebo-controlled crossover safety population contained 12 people, and the randomized trial did not show superiority over placebo on its two primary endpoints. The longer open-label extension informed the muscle-strength finding used for approval. That supports one defined indication, not a license to extrapolate to exercise recovery, fatigue, or anti-aging.
| What's cited | Range |
|---|---|
| FDA-labeled dose (Forzinity, Barth syndrome, at least 30 kg) | 40 mg subcutaneous once daily |
| Adults with severe renal impairment not on dialysis | 20 mg subcutaneous once daily, per label |
| Dose for longevity, athletic performance, or a research vial | Not established |
The label's 40 mg once-daily subcutaneous dose applies to the approved Forzinity product in people with Barth syndrome weighing at least 30 kg. It is not a protocol for other conditions, a reconstituted research vial, or a performance stack.
In the label's 12-person placebo-controlled crossover safety population, any local administration reaction occurred in all 12 people on elamipretide and in 8 of 12 on placebo. Erythema occurred in 12 of 12 on elamipretide versus 3 of 12 on placebo. These small-study figures are descriptive, not a forecast for a different population.
| Signal | Frequency | Context |
|---|---|---|
| Injection-site reactions | commonly reported | In the 12-person crossover safety population, any local reaction occurred in 12 of 12 on elamipretide and 8 of 12 on placebo. |
| Hypersensitivity reactions | occasionally reported | The label describes serious allergic reactions requiring emergency intervention in some patients. |
| Use outside Barth syndrome | unknown / not studied | The approval data do not establish safety or benefit for wellness, anti-aging, or athletic use. |
Check the product, population, endpoint, and label before treating a study as your protocol.