Elamipretide vs SS-20
Written by Aaron CuhaReviewed Sep 2026
The short answer
The peptide that became an approved drug, and its sibling. The sibling cannot mop up free radicals at all, and it works anyway in rats and mice. SS-20 was the test that showed the drug does not work just as an antioxidant. It has no human study and no registered trial.
- Elamipretide people
- 487
- Elamipretide nulls
- 3
- SS-20 people
- 0
- SS-20 nulls
- 0
Dose
Approved medicine. No human dose established for unlabelled uses
Labeled amounts sit on the prescribing information. This page records what trials measured, not a personal dose.
FDA-approved September 19, 2025 as Forzinity for Barth syndrome, a rare inherited disease. It was an early, conditional (accelerated) approval. Other uses are investigational
Dose
No human dose established
No published study on this page has given this compound to people and reported a result.
4 animal studies, 1 lab study, no human study
First-hand reports are counted on each profile and never added together. This page sets two published records side by side. It does not pick a winner.
Column A
ElamipretideElamipretide (SS-31, mitochondrial-targeted peptide)
Approved in 2025 for one rare genetic disease, Barth syndrome, on a result its own main study missed. In a large final-stage study in an inherited muscle disease, it clearly did not help.
Column B
SS-20SS-20 (Phe-D-Arg-Phe-Lys-NH2), Szeto-Schiller mitochondria-targeted peptide
The sister of SS-31, the peptide that became the approved drug elamipretide. SS-20 cannot mop up free radicals, the unstable molecules that damage cells. That made it a useful test case, and it worked anyway in rats and mice. There is no human study and no registered trial.
Side by side, on the facts we can check
| What we compare | Elamipretide | SS-20 |
|---|---|---|
| Category | Anti-aging | Antioxidant |
| FDA status | FDA-approved September 19, 2025 as Forzinity for Barth syndrome, a rare inherited disease. It was an early, conditional (accelerated) approval. Other uses are investigational | Not approved, and never sent to a regulator. Its sister drug SS-31, elamipretide, got US accelerated approval in 2025, a faster route based on early signs of benefit, for Barth syndrome, a rare inherited disease. SS-20 has no legal 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. |
| How it works | It sticks to cardiolipin, a fat in the inner wall of mitochondria. That helps hold the folds of the wall in shape, so the cell's power plant makes energy (ATP) better. | SS-20 goes to the inner wall of mitochondria and sticks to cardiolipin, a fat found there. That protects cytochrome c, a protein that passes energy along the chain inside mitochondria. When blood flow stops, a key link inside cytochrome c breaks. The broken protein clogs the energy chain. It also starts damaging cardiolipin, which breaks down another protein, OPA1, and lets cytochrome c leak out. By keeping that link intact, SS-20 keeps the energy chain running smoothly. That is why it looks like an antioxidant even though it has no mopping-up chemistry. It cuts how many harmful oxygen molecules get made, instead of cleaning them up afterwards. |
| Studies in people | 5 | 0 |
| Evidence | Moderate: 5 completed trials, 487 people given it | Animal or lab only: 4 animal studies, 1 lab study, no human study |
| 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 one rare genetic disease, Barth syndrome, on a result its own main study missed. In a large final-stage study in an inherited muscle disease, it clearly did not help. SS-20: The sister of SS-31, the peptide that became the approved drug elamipretide. SS-20 cannot mop up free radicals, the unstable molecules that damage cells. That made it a useful test case, and it worked anyway in rats and mice. There is no human study and no registered trial.
Which has stronger research evidence, Elamipretide or SS-20?
Each compound gets a band worked out from facts we counted, with the math shown. Elamipretide is Moderate (5 completed trials, 487 people given it). SS-20 is Animal or lab only (4 animal studies, 1 lab study, no human study). That counts how much has been done in people. It does not rate whether either one works, and neither one is called the winner.
Are Elamipretide and SS-20 FDA-approved?
Elamipretide: FDA-approved September 19, 2025 as Forzinity for Barth syndrome, a rare inherited disease. It was an early, conditional (accelerated) approval. Other uses are investigational. SS-20: Not approved, and never sent to a regulator. Its sister drug SS-31, elamipretide, got US accelerated approval in 2025, a faster route based on early signs of benefit, for Barth syndrome, a rare inherited disease. SS-20 has no legal status of any kind..
Related posts
Blog articles that cover Elamipretide or SS-20, newest first.
- Longevity / Sep 27, 2026 / 12 minPeptides for Longevity: What the Evidence Actually Shows in 2026
- Safety / Sep 27, 2026 / 9 minPeptide Side Effects by Class: What Is Documented, What Is Anecdotal
- Safety / Sep 27, 2026 / 8 minHow to Read a Peptide Certificate of Analysis: HPLC Purity, Mass Spec Identity, Endotoxin, and Janoshik Verification
- Longevity / Sep 27, 2026 / 7 minSS-31 and Elamipretide: What the Forzinity Approval Does and Does Not Mean
Reviewed Sep 2026. This page puts two published records side by side. It is for learning, and it is not medical advice. When this site shows a dose, it is the dose a trial or a clinic actually used, or what people say they did, with the source attached. None of it tells you what to take.