SS-31

FDA-approved

Also known as: Elamipretide, Forzinity

Structure source: PubChem CID 11764719 (elamipretide). [D-Arg] is D-arginine; [Dmt] is 2',6'-dimethyltyrosine

SS-31, also called elamipretide, is a lab-made chain of four amino acids that is drawn into mitochondria, the cell's energy-making parts. There it binds cardiolipin, a fat in the inner membrane where energy is made. As Forzinity, it is approved to improve muscle strength in people with Barth syndrome, a rare inherited mitochondrial disease.

Approved for improving muscle strength in adults and children with Barth syndrome who weigh at least 30 kg (as Forzinity). This is an accelerated approval, based on improved knee muscle strength; continued approval may depend on a confirmatory trial.

How it works

In lab studies, it binds tightly to cardiolipin, a fat needed to form the folded inner membrane where mitochondria make energy.
In rats, it protected these membrane folds when blood flow to the kidney was cut off. Energy (ATP) levels recovered faster once blood flow returned.
In lab studies, peptides of this family built up about 1,000-fold in the inner mitochondrial membrane and lowered harmful oxygen by-products.
The body breaks it down into inactive pieces that leave through the urine.

Evidence

Barth syndrome

Early human evidenceCEBM Level 2–4

In a placebo-controlled crossover trial in 12 patients (12 weeks on each), it did not improve walking distance or fatigue, the main goals. In the open-label extension, which had no placebo group, walking distance, fatigue and knee muscle strength improved over time. Walking gains held in the 8 patients followed for more than three years.

Longevity and recovery

Tested: no benefit shownCEBM Level 2

Support comes mainly from lab and animal studies, such as protection of kidney mitochondria in rats. In one small trial in 39 healthy older adults, a single dose briefly raised muscle energy capacity but did not improve muscle fatigue. No trial in people has shown a clinical benefit for healthy aging or recovery.

Mitochondrial muscle disease

Tested: no benefit shownCEBM Level 1b

In a 24-week placebo-controlled trial in 218 adults with inherited mitochondrial muscle disease, it did not improve walking distance or fatigue, its two main goals. It was well tolerated.

Caveats

Injection-site reactions are very common. In the Barth trial, all 12 patients had skin redness, and most had pain, hardening or itching.
Serious allergic reactions needing emergency care have been reported. Anyone who has had a serious allergic reaction to it or its ingredients should not use it.
It leaves the body through the kidneys, so kidney disease raises blood levels. It has not been studied in people on dialysis.
There are no data on its use in pregnancy.
In a 4-week placebo-controlled trial in 71 people with heart failure, it did not improve heart size or pumping. An earlier single-infusion study saw a brief drop in heart volumes at the highest dose. In a trial during treatment for a heart attack, it did not reduce heart damage.
A phase 2 trial in dry age-related macular degeneration, an eye disease, missed its main goals; a larger trial is under way.

References

Reviewed by Shubham Gupta, MD — Founder & President · October 31, 2026

This page is for education only. It is not medical advice. Decisions about any treatment belong with a physician who knows your history.