Head to head
Elamipretide against SS-20
The peptide that became an approved drug and its sibling, which cannot scavenge free radicals at all and works anyway in rats and mice. SS-20 was the control that proved the mechanism was not simple antioxidant activity, and it has no human study and no registered trial.
Column A
ElamipretideElamipretide (SS-31, mitochondrial-targeted peptide)
Approved in 2025 for a rare genetic disease on an endpoint its own randomised trial missed. The phase 3 trial in mitochondrial myopathy is Class I evidence of no effect.
Column B
SS-20SS-20 (Phe-D-Arg-Phe-Lys-NH2), Szeto-Schiller mitochondria-targeted peptide
The sibling of SS-31, the peptide that became the approved drug elamipretide. SS-20 cannot scavenge free radicals at all, which made it the control that proved a point, and it works anyway in rats and mice. There is no human study and no registered trial.
Side by side, on the facts we can check
| Attribute | Elamipretide | SS-20 |
|---|---|---|
| Category | Anti-aging | Antioxidant |
| FDA status | FDA-approved September 19, 2025 as Forzinity (accelerated approval) for Barth syndrome; other uses investigational | Not approved and never submitted. Its sibling SS-31, elamipretide, received accelerated United States approval in 2025 for Barth syndrome. SS-20 has no regulatory status of any kind. |
| Half-life | ~2-3 hours | Not established. No pharmacokinetic study in humans exists, and the animal work used pretreatment or continuous infusion schedules rather than single-dose kinetics. |
| Molecular weight | 639.8 Da | About 611 Da for the tetrapeptide amide. |
| Mechanism | Binds cardiolipin in the inner mitochondrial membrane, stabilizing cristae structure and improving electron transport efficiency and ATP production. | Selective targeting of cardiolipin in the inner mitochondrial membrane, where it preserves the methionine 80 to iron ligation of cytochrome c. Ischaemia disrupts that ligation, producing a globin-like pentacoordinated heme that inhibits electron transport and turns cytochrome c into an oxygenase, which peroxidises cardiolipin and drives OPA1 degradation and cytochrome c release. By protecting the ligation, SS-20 keeps electron transport efficient and improves coupling of oxidative phosphorylation, which is why its effects look antioxidant without any scavenging chemistry: it reduces reactive oxygen species production rather than mopping them up. |
| Human studies cited | 2 | 0 |
| Legal status, US | FDA-approved (Forzinity, Barth syndrome only), prescription only; other uses investigational | Not approved; research use only |
Frequently asked questions
What is the difference between Elamipretide and SS-20?
Elamipretide: Approved in 2025 for a rare genetic disease on an endpoint its own randomised trial missed. The phase 3 trial in mitochondrial myopathy is Class I evidence of no effect. SS-20: The sibling of SS-31, the peptide that became the approved drug elamipretide. SS-20 cannot scavenge free radicals at all, which made it the control that proved a point, and it works anyway in rats and mice. There is no human study and no registered trial.
Which has stronger research evidence, Elamipretide or SS-20?
This database does not grade compounds. It counts what was run in people: 2 of the 4 studies cited on the Elamipretide profile were human work, against 0 of 5 for SS-20. Those counts are of our own citation lists and understate any larger literature, and neither is a recommendation.
Are Elamipretide and SS-20 FDA-approved?
Elamipretide: FDA-approved September 19, 2025 as Forzinity (accelerated approval) for Barth syndrome; other uses investigational. SS-20: Not approved and never submitted. Its sibling SS-31, elamipretide, received accelerated United States approval in 2025 for Barth syndrome. SS-20 has no regulatory status of any kind..
Related posts
Blog articles that cover Elamipretide or SS-20, newest first.
- Longevity / Sep 8, 2026 / 12 minPeptides for Longevity: What the Evidence Actually Shows in 2026
- Safety / Sep 8, 2026 / 9 minPeptide Side Effects by Class: What Is Documented, What Is Anecdotal
- Safety / Sep 8, 2026 / 8 minHow to Read a Peptide Certificate of Analysis: HPLC Purity, Mass Spec Identity, Endotoxin, and Janoshik Verification
- Longevity / Sep 8, 2026 / 7 minSS-31 and Elamipretide: What the Forzinity Approval Does and Does Not Mean
Reviewed Sep 2026. This page sets two published records side by side. It is educational, it is not medical advice, and it contains no dosing protocols or recommendations for personal use.