Did the FDA approve SS-31? Yes, for one rare disease
Disclosure: Dr. Peppa is owned and operated by Medtruva LLC, which sells peptide products, including some compounds discussed on this site. Advertisements are labeled.
The short answer
- Yes. FDA approved elamipretide (SS-31) on September 19, 2025, as Forzinity.
- The approval covers Barth syndrome only, a genetic condition diagnosed in a few hundred people worldwide.
- It's an accelerated approval based on muscle strength in a 12-patient trial, with a confirmatory trial required.
- Every other use, including energy, longevity, brain and kidney uses, is unapproved.
What was approved
FDA granted accelerated approval to elamipretide on September 19, 2025. It is sold as Forzinity by Stealth BioTherapeutics, as an injection given under the skin.
The approved indication, in the label's words, is "to improve muscle strength in adult and pediatric patients with Barth syndrome weighing at least 30 kg."
Barth syndrome is a genetic condition affecting cardiolipin, a molecule in the inner membrane of mitochondria. It causes muscle and heart weakness and is diagnosed in a few hundred people worldwide.
What accelerated approval means here
Accelerated approval lets FDA approve a drug for a serious condition based on a measure that is expected to predict benefit, rather than the benefit itself. The company must then run a confirmatory trial.
The label is explicit: the indication is approved "based on an improvement in knee extensor muscle strength, an intermediate clinical endpoint," and continued approval "may be contingent upon verification and description of clinical benefit in a confirmatory trial(s)."
Two further details from FDA's own documents are worth knowing:
- The randomized part of the trial missed its goals. The label says the crossover trial in 12 patients "was not superior to placebo" on walking distance and fatigue. The strength increases "were not observed during the randomized trial but were observed during the extension period," the open-label phase without a comparison group.
- The confirmatory trial is registered with a target of 48 patients and completion scheduled for late 2029.
What was not approved
Everything else. SS-31 is discussed online for fatigue, brain injury, kidney disease, diabetes and general anti-aging. None of those is an approved use, and most of that research is in mice.
In humans, the larger trials have mostly missed their goals: a 218-patient trial in primary mitochondrial myopathy, a 300-patient trial in heart attack patients, a 71-patient heart failure trial and a 176-patient trial in macular degeneration.
What that means for material sold as "SS-31"
Now that elamipretide is an approved drug, material sold under the SS-31 name by research-chemical vendors is a different thing from the approved product, which has a manufacturer, a label and a specialty pharmacy distribution channel.
On August 24, 2026, FDA issued warning letters to several peptide sellers naming SS-31 among the products it considers unapproved new drugs, citing sellers' own marketing as evidence the products were meant for people.
Sources
- FDA, Accelerated approval of the first treatment for Barth syndrome (19 September 2025) — https://www.fda.gov/news-events/press-announcements/fda-grants-accelerated-approval-first-treatment-barth-syndrome
- FORZINITY (elamipretide) prescribing information (September 2025) — https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/215244s000lbl.pdf
- FDA, Integrated Review, NDA 215244 — https://www.accessdata.fda.gov/drugsatfda_docs/nda/2025/215244Orig1s000IntegratedR.pdf
- Confirmatory trial NCT07531251 — https://clinicaltrials.gov/study/NCT07531251
- Karaa et al., MMPOWER-3, Neurology (2023) — https://pubmed.ncbi.nlm.nih.gov/37268435/
- FDA, Warning Letter to Peak Performance Peptides (24 August 2026) — https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/peak-performance-peptides-735127-08242026