Dr. Peppa

SS-31 got FDA approval. Here's exactly what that approval covers.

Published by Dr. Peppa ·

Title graphic reading 'SS-31 is FDA-approved. For one rare disease.' beside a portrait of a doctor in scrubs
AI-generated illustration. Not a photo from the video.

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 quick version

  • SS-31 (elamipretide) was approved by the FDA on September 19, 2025 for Barth syndrome, a condition affecting a few hundred people worldwide.
  • The approval came through the accelerated pathway, based on a muscle-strength measure in a 12-patient trial. FDA's own clinical and statistical reviewers recommended rejecting it and were overruled.
  • Elsewhere in humans, the record is mostly negative: a 218-patient trial in mitochondrial myopathy, a 300-patient heart-attack trial, a 71-patient heart failure trial and a 176-patient eye trial all missed their main goals.
  • The dementia, brain injury, kidney and anti-aging uses discussed online are animal research. For chronic fatigue and long COVID there is no human trial at all.

Disclosure for this one in particular: Medtruva, which owns this site, sells SS-31 for laboratory research. Nothing here is a recommendation to buy or use it.

The video

SS-31 (Elamipretide): FDA-Approved Mitochondrial Peptide was published on November 28, 2025 by Dr. Quinn Stillson, MD. It runs 27 minutes and has about 130,000 views.

He is an MD from the University of Chicago's Pritzker School of Medicine and medical director at an integrative clinic in Indiana. His certifications in anti-aging and peptide therapy come from A4M, a private organization whose credentials are separate from the specialty boards recognized by the American Board of Medical Specialties. His website lists a supplement dispensary where he earns commission, a paid membership, consulting for investment firms, and brand partnerships. His clinic sells peptide therapy.

His video carries no sponsor or affiliate links, and it states up front that every use besides Barth syndrome is off-label.

A note on what we left out: roughly a third of the video covers dosing, injection frequency and cycle lengths, including conversions from mouse studies to human amounts. We don't publish dosing information. What follows is the science, the regulatory record and the evidence.

What SS-31 is, and how it's thought to work

SS-31 is a synthetic peptide of just four amino acids. Its small size and positive charge let it cross membranes and reach the inner membrane of the mitochondria, the structures that produce most of a cell's energy.

The standard explanation, which the video gives well, goes like this: the electron transport chain embedded in that membrane leaks electrons, creating reactive oxygen species. Those damage cardiolipin, a phospholipid that keeps the membrane and its protein complexes stable. Damaged cardiolipin means a less stable chain, which leaks more, which causes more damage. SS-31 binds cardiolipin and interrupts that cycle.

Two things are worth adding.

The mechanism is established in test tubes and animals, not people. The foundational work is in isolated mitochondria and rats.

The target itself is contested. A 2020 study argued the compound's affinity is driven by membrane surface charge generally rather than cardiolipin specifically. A 2024 study identified a different protein, PLSCR3, as essential: knock it out in mice and SS-31's protective effect disappears entirely. FDA's own reviewers wrote that the cardiolipin-stabilization idea is "possible" but that "no empirical data are available to confirm this hypothesis."

The FDA-approved label describes it simply as a cardiolipin binder that improves mitochondrial structure and function, without asserting a proven human mechanism.

The approval, in detail

On September 19, 2025, FDA granted accelerated approval to elamipretide, sold as Forzinity, "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 directly, diagnosed in a few hundred people worldwide.

Three details matter and rarely appear in summaries.

The trial didn't meet its main goals. The label itself says the randomized crossover trial in 12 patients "was not superior to placebo" on both primary endpoints, walking distance and fatigue. On knee extensor strength, the label says increases "were not observed during the randomized trial but were observed during the extension period" — the open-label phase where everyone knew they were getting the drug and there was no comparison group.

FDA's review staff wanted to reject it. According to the agency's own integrated review, the clinical and biostatistics teams and the cross-discipline team leader recommended a Complete Response, concluding the controlled trial did not demonstrate a treatment effect and the extension could not be interpreted as evidence of one. The signatory authority overruled them, accepting "a somewhat greater risk (compared to a randomized trial) of false positive conclusions — and therefore less certainty about effectiveness," given how rare the disease is and how few options exist.

It took three tries. FDA refused to file the original application in 2021. An advisory committee voted 10–6 in favor in October 2024. FDA issued a rejection letter in May 2025, and the company publicly questioned its own survival. The approval came on the third resubmission.

Accelerated approval is conditional: a confirmatory randomized trial is required, now registered with a target of 48 patients and completion scheduled for late 2029.

What happened in the other human trials

This is the part the online conversation skips. Elamipretide has been tested in several conditions, and the pattern is consistent.

Trial Condition Participants Result
MMPOWER-3 Primary mitochondrial myopathy 218 Missed both goals: walking distance and fatigue
EMBRACE STEMI Heart attack during angioplasty 300 No reduction in infarct size
PROGRESS-HF Heart failure 71 No change in heart volumes or ejection fraction
ReCLAIM-2 Dry macular degeneration 176 Missed both goals; some positive secondary measures
MOTION Older adults, 60–85 39 Mixed: one ATP measure just missed significance, another met it; no effect on fatigue resistance
Renal artery pilot Kidney artery stenting 14 Better kidney blood flow and function than stenting alone

The video is fair about two of these: it says the heart failure and macular degeneration results weren't impressive. But it presents the 218-patient mitochondrial myopathy trial as safety evidence without mentioning that the trial failed on efficacy. That trial is the largest controlled test of this compound ever run, and the authors' conclusion was that elamipretide "did not improve outcomes."

A later subgroup analysis of that same trial found a benefit in patients with one genetic subtype. Subgroup findings from a failed trial are a reason to run another study, not a result.

The MOTION study in older adults is the closest thing to human evidence for the "healthy aging" use. Its own authors report that one ATP measure narrowly missed statistical significance, another met it, and there was no significant effect on muscle fatigue resistance. It was funded by the manufacturer.

The uses that are animal research

The video is generally careful here, repeatedly saying "we don't have human studies on this yet." That's accurate, and worth restating plainly:

Chronic fatigue and long COVID deserve a separate line. There is no registered or published human trial of elamipretide in chronic fatigue syndrome, ME/CFS or long COVID. The video says so too, describing the case as speculative. The closest human fatigue data are negative: fatigue was a failed endpoint in both the Barth syndrome and mitochondrial myopathy trials.

Safety

The video's read is that safety looks good, and the trial record broadly supports that. Across several long trials, the dominant adverse events were injection-site reactions. The FDA label adds detail the video doesn't:

Injection versus oral

The video's point here is good and worth repeating: intestinal transporters carry peptides of two or three amino acids, but not four. SS-31 has four, so it's likely to be poorly absorbed and readily broken down by mouth.

The record supports the caution, if not the specific claim: there is no oral formulation in any registered elamipretide trial, and FDA's review contains no oral absorption data at all. We also couldn't find a study that directly measured oral bioavailability and found it poor. The approved product is injected under the skin and is explicitly not approved for intravenous use.

Where it's sold, and a very recent development

The video ends by advising viewers to get SS-31 from a compounding pharmacy rather than a research-chemical website, on the grounds that one is regulated and the other isn't.

Something happened after that video was published that's relevant to anyone following this compound. On August 24, 2026, FDA issued warning letters to several peptide sellers naming SS-31 (elamipretide) specifically as an unapproved new drug. One letter quotes the seller's own site describing SS-31 as researched for "mitochondrial repair, anti-aging, neuroprotection," and treats that marketing as evidence the product was intended for people, regardless of a research-use label.

Now that elamipretide is an approved drug with a named manufacturer, an indication and a label, the gap between that product and material sold under the same chemical name is a matter of record rather than speculation.

The bottom line

SS-31 is the rare peptide with a real FDA approval, and the video is right that this makes it unusual. But the approval is for one ultra-rare genetic disease, it rests on an uncontrolled extension of a 12-patient trial, FDA's own review staff argued against it, and a confirmatory trial won't report until the end of the decade.

Everything past that is either a failed trial in humans or a promising result in mice. That isn't an argument that SS-31 does nothing. It's the difference between a mechanism that makes sense and a treatment that's been shown to work, and for this compound, outside of a few hundred patients with Barth syndrome, that difference hasn't been closed yet.

Sources

The video

FDA and regulatory records

Human trials

Mechanism and preclinical