Name check
One molecule, four names
SS-31, elamipretide, MTP-131, and Bendavia are names used in the research literature for the same molecule[5]. Pick a name to see where it shows up.
Research code
SS-31
The name you will hear most in wellness commentary. A research identity is not a wellness outcome, and it does not mean every product sold under this name shares the approved medicine's identity or quality[5].
Mechanism vs. outcome
Where the pitch meets the evidence
The underlying question is a fair one: does targeting mitochondria translate into something you can feel? Read the claim three ways.
Commentary · October 15, 2026 episode
Peptide Of The Week published an episode titled "Should You Ever Stop Taking R? | Peptide of the Week Q&A" on October 15, 2026[7]. The identity-matched video carries the title "Should You Ever Stop Taking R? The Truth About Long Term Use | Peptide of the Week Q&A"[6].
The machine transcript of that episode includes a broad claim about SS-31, which we paraphrase as saying the compound will repair the mitochondria[4]. We use that claim only to identify the question worth checking, not to endorse the wording or reproduce the surrounding dose and combination advice[4].
Provenance boundary: The publisher's machine transcript has not been independently audio-verified, so nothing here quotes the episode's speech, cites video timestamps, or claims episode length[4]. The claim is commentary: a pitch worth checking against published evidence, not evidence in its own right[4].
Cell level · September 2025 FDA label
Mechanism has a narrower meaning than marketing. The original September 2025 FDA prescribing information describes elamipretide as a mitochondrial cardiolipin binder that localizes to the inner mitochondrial membrane and improves mitochondrial morphology and function[3].
What that statement is
A statement about what the molecule does at the cellular level[3].
What it is not
A statement that a healthy 45-year-old will feel less tired, train harder, or live longer.
Three questions for any mechanism pitch
When you hear a mechanism pitch, ask about the outcome, not just the target.
- Question 01
What happened in people?
Did symptoms or function change, or only something in a cell?
- Question 02
With what diagnosis?
A rare genetic disease, or healthy men in midlife?
- Question 03
Against what comparison?
A blinded placebo group, or an open-label phase where everyone knew they got the drug?
Phase 3 trial
What the randomized trial actually tested
MMPOWER-3 was a randomized, double-blind, placebo-controlled phase 3 study of 218 participants with primary mitochondrial myopathy[1]. Researchers measured walking distance during a six-minute test and a disease-specific fatigue score after 24 weeks[1].
MMPOWER-3 · Neurology, 2023
Primary endpoints not met- participants with primary mitochondrial myopathy
- 218
- double-blind, placebo-controlled
- 24 wk
- evidence rating stated in the paper
- Class I
Primary endpoints · all 218 participants
Not met- Six-minute walk distance vs placebo
- Not met
- Disease-specific fatigue score vs placebo
- Not met
These were functional, symptom-level outcomes — the things you would actually care about — not a diagram of a cell. The study provides Class I evidence that elamipretide does not improve walking distance or fatigue at 24 weeks compared with placebo in patients with primary mitochondrial myopathy[1].
Exploratory, post hoc analysis
Hypothesis-generatingThe publication also reports an exploratory post hoc walking-distance signal in a nuclear-DNA subgroup, which the authors describe as hypothesis-generating[1].
That is a signal worth studying further, not a rescue of the negative overall result, and it is not a benefit claim for anyone without that diagnosis[1].
Who paid
The trial was funded by the drug's developer, Stealth BioTherapeutics, and the funding organization participated in study design[1].
Who was studied
It was not a trial of healthy men looking for better workouts. It studied people with a diagnosed mitochondrial muscle disease[1].
A negative trial in one disease does not negate every other potential indication, and a positive result elsewhere would not validate treating ordinary midlife fatigue. Keep both edges of that line.
Regulatory record
What the FDA approval does — and does not — tell you
On September 19, 2025, FDA announced accelerated approval of Forzinity (elamipretide) as the first treatment for Barth syndrome, in patients weighing at least 30 kg[2].
The original prescribing information, revised 9/2025, specifies improving muscle strength in adult and pediatric patients with that condition[3].
Why the accelerated-approval details matter
- Intermediate endpoint. FDA based the approval on knee-extensor muscle strength, an intermediate clinical endpoint considered reasonably likely to predict patient benefit[2][3].
- Confirmatory trial required. FDA required a post-approval randomized, double-blind, placebo-controlled trial to confirm that the strength changes translate to real patient benefit[2].
- Contingent approval. The original label makes continued approval potentially contingent on verification of that clinical benefit[3].
Label context that rarely makes it into the promotion[3]
Randomized Barth trial
Blinded placebo controlDid not show superiority on walking distance or fatigue[3].
Participants were compared against a placebo group.
None of this erases the milestone. Barth syndrome is a serious rare disease, and the September 19, 2025 announcement describes this as the first approved treatment for it[2].
But it is a specific medical record for a specific condition. It is not approval of the phrase "mitochondrial repair" for anyone who feels run down, and it is not evidence that a product sold as SS-31 is the approved medicine.
This page reports two dated official records, the September 19, 2025 announcement[2] and the original label revised 9/2025[3], as retrieved on October 23, 2026. That is a record-access date, not a label revision or a check of the current label, and it is not a full survey of regulatory status.
Safety
Risks are part of the same record
FDA label · September 2025
Injection-site and allergic reactions
The September 2025 label reports injection-site reactions and warns of hypersensitivity, including serious allergic reactions requiring emergency medical intervention[3].
"Mostly mild" and "not deemed related" are not the same as risk-free, and neither is a mechanism of action.
Before your appointment
Questions worth taking to a qualified clinician
This is educational material, not a diagnosis or a recommendation to start, stop, or change anything.
If persistent fatigue is your concern, bring the concern — not a shopping list — to a qualified clinician. Pick the questions you want on your appointment note.
How to judge a peptide claim
Ask what happened in people
A mechanism describes a cell. It does not tell you whether anyone walked farther or felt less tired. Look for symptom and function outcomes.
Match the diagnosis
MMPOWER-3 studied primary mitochondrial myopathy and the approval covers Barth syndrome. Neither population is healthy men in midlife.
Check the comparison
A blinded placebo group is the test that counts. Gains seen in an open-label extension, where everyone knew they got the drug, are weaker evidence.
Read what the approval actually covers
An approval is specific to a product, a condition, and a patient group. It does not transfer to a different use or to a product sold under a research name.
Who this might suit, and who should avoid it
Might suit
- The man hearing "mitochondrial repair" pitched as an energy fix who wants the record before deciding anything.
- Readers who want to know what the elamipretide trial and the 2025 approval actually showed.
Should avoid
- Anyone looking for a fix for ordinary midlife fatigue. Persistent fatigue needs an evaluation, not an unapproved product.
- Anyone considering a product sold as "SS-31." It is not the approved medicine, and its identity and quality are unknown.
- Anyone with a history of serious allergic reactions. The label warns of hypersensitivity that can require emergency care.
Common questions
Is SS-31 a real research molecule?
Yes. SS-31 is also known as MTP-131, elamipretide, and Bendavia in the research literature. That establishes a research identity, not a wellness outcome, and it does not mean every product sold under that name shares the approved medicine's identity or quality.
Does this evidence prove an energy benefit in healthy men over 40?
No. MMPOWER-3 studied primary mitochondrial myopathy, not that population, and its overall walking and fatigue endpoints were not met. That is a finding about one studied population, not a claim that no healthy-adult research exists anywhere.
Does FDA approval settle the anti-aging question?
No. The September 19, 2025 approval announcement concerns Barth syndrome, and the original September 2025 label specifies improving muscle strength in adult and pediatric patients with that condition. Neither establishes a longevity or general-wellness outcome.
Sources
This guide is education, not medical advice. Talk to a qualified clinician before starting, stopping, or changing any peptide, hormone, or supplement.