MOTS-c vs SS-31: Which Is Better for Mitochondrial Health?
Should I run MOTS-c or SS-31?
MOTS-c scores 6.5 and SS-31 6.0, and neither one has a human trial behind the use you want. MOTS-c takes blood sugar and body composition. SS-31 takes the mitochondria itself and the eye. MOTS-c runs $100 to $200 a month against $200 to $500 a month for SS-31.
- MOTS-c 6.5, SS-31 6.0. Both are gray market, both are injected, and both are scored mostly on mechanism rather than human outcome trials.
- MOTS-c has zero published human interventional efficacy trials. Every efficacy claim traces to mouse work or human blood-level observations.
- SS-31 has real human trials and most of them missed: MMPOWER-3 in mitochondrial myopathy, ReCLAIM-2 in dry AMD, PROGRESS-HF in heart failure.
- SS-31 is FDA approved as Forzinity, for Barth syndrome only, at 40 mg a day. Gray-market protocols run 5 to 10 mg a day, so a quarter of the studied dose or less.
- Many of their use-case subratings sit at the floor value of 1.0, which means nobody has scored evidence there, not that it was tested and failed.
- MOTS-c is prohibited for tested athletes under WADA S4.4 as an AMPK activator. That is a hard stop, not a caution.
At a Glance
MOTS-c
- Efficacy 3.0
- Breadth 3.6
- Evidence 2.6
- Speed 2.6
- Durability 1.8
- Bioindividuality 2.6
- Safety Risk 1.3
- Side Effects 1.3
- Cost 3.0
- Effort 3.0
- Opportunity Cost 2.5
- Dependency 1.0
- Reversibility 1.2
- Mitochondrial
- Metabolic Health
- Blood Sugar
- Body Composition
Mitochondrial-derived peptide that activates AMPK, an exercise mimetic in mice. BioHarmony 6.5, worth trying.
SS-31 (Elamipretide)
- Efficacy 3.5
- Breadth 3.0
- Evidence 3.8
- Speed 2.0
- Durability 1.8
- Bioindividuality 2.8
- Safety Risk 2.0
- Side Effects 2.2
- Cost 3.8
- Effort 3.2
- Opportunity Cost 1.5
- Dependency 2.0
- Reversibility 1.3
- Mitochondrial
- Antioxidant
- Cardiovascular
- Neuroprotection
Cardiolipin-binding peptide, approved as Forzinity for Barth syndrome only. BioHarmony 6.0, worth trying.
Head-to-Head Verdict
| Use Case | Winner | Rationale |
|---|---|---|
| Mitochondrial | SS-31 (Elamipretide) | SS-31 8.5 against MOTS-c 6.5, the highest subrating either peptide holds anywhere. SS-31 acts directly on the organelle: Birk 2013 showed it binds cardiolipin, protects cristae membranes and speeds ATP recovery after ischemia. MOTS-c signals through AMPK instead. If the mitochondrion itself is the target, SS-31 is the one aimed at it. |
| Blood Sugar | MOTS-c | MOTS-c 6.0 against SS-31 2.5. Lee 2015 discovered MOTS-c and showed it reduced obesity and insulin resistance in mice through AMPK activation and GLUT4 handling. Human evidence stops at blood levels: Zhou 2024 pooled seven biomarker studies and found lower MOTS-c in diabetes, with the obesity subgroup pointing the other way. Nobody has injected it in a trial. |
| Body Composition | MOTS-c | MOTS-c 5.5 against SS-31 2.5, on the exercise-mimetic mechanism rather than on results in people. Lee 2015 reported reduced obesity in mice and Reynolds 2021 tied exercise-induced endogenous MOTS-c to physical capacity. Read that carefully: exercise raises your own MOTS-c, which is not the same as injecting it producing the same adaptation. |
| Metabolic Health | MOTS-c | MOTS-c 6.0 against SS-31 3.0, and metabolic signaling is the whole reason MOTS-c exists. It inhibits ATIC in the purine pathway, AICAR accumulates, AMPK switches on. Yen and Cohen 2019 frame it as an insulin sensitizer. The gap is real, and it is a mechanistic gap: the closest regulated program is CB4211, a MOTS-c analog in phase 1, not MOTS-c itself. |
| Antioxidant | SS-31 (Elamipretide) | SS-31 6.0 against MOTS-c 1.0. That 1.0 is a floor value meaning nobody scored evidence for MOTS-c here, not that it was tested and failed. SS-31's case is direct: stabilizing cardiolipin and cristae architecture cuts the mitochondrial ROS leak at source, which Szeto 2014 describes as the defining property of the SS peptide class. |
| Neuroprotection | SS-31 (Elamipretide) | SS-31 5.5 against MOTS-c 1.0, another floor value on the MOTS-c side. The SS-31 score rests on mechanism and on mitochondrial disease context rather than on a neuroprotection trial. The Mitochondrial Medicine Society's care standards endorse supportive and organ-specific management, with no broad endorsement of SS-31 for general mitochondrial dysfunction. |
| Eye Vision | SS-31 (Elamipretide) | SS-31 5.0 against MOTS-c 1.0, and this row comes with a failed trial attached. ReCLAIM-2 randomized 176 patients with dry age-related macular degeneration and missed its primary endpoints for low-luminance acuity and geographic atrophy area. Exploratory ellipsoid-zone and letter-gain signals survived, and injection-site reactions were common. A win here means a hypothesis worth watching. |
| Cardiovascular | Tie | The subratings say SS-31 5.5 against MOTS-c 3.0, and the trials say call it even. Butler 2020 randomized 71 heart failure patients to 4 mg or 40 mg daily for 28 days: well tolerated, no improvement in left ventricular volume or ejection fraction. Daubert 2017 found favorable acute changes from a single infusion in 36 patients, which did not translate. MOTS-c has no cardiovascular trial at all. |
| Longevity | Tie | MOTS-c 4.0 against SS-31 5.0, close enough to be a tie, and both rest on indirect evidence. The MOTS-c story is a genetics finding: Fuku 2015 tied the K14Q variant to exceptional longevity in a Japanese population, which says nothing about injecting it. SS-31's is Siegel 2013 restoring mitochondrial energetics in aged mice. No human endpoint either way. |
Cost Comparison
| Intervention | Monthly Cost | Notes |
|---|---|---|
| MOTS-c | $100 to $200 | Extracted from the report, priced 2026-09-07, research-vendor channel. The figure covers 5 to 10 mg subcutaneous three times a week from research peptide vendors, which is the common gray-market protocol.Add the consumables the headline price hides: syringes, bacteriostatic water, alcohol swabs, sharps disposal and cold-chain shipping. There is no approved product, so there is no insurance path and no pharmacy price to compare against. |
| SS-31 | $200 to $500 | Extracted from the report, priced 2026-09-07, research-vendor channel. The figure covers gray-market protocols of 5 to 10 mg a day. The approved product, Forzinity, is priced as an orphan drug and is Barth syndrome specific.The dose is the problem with this price. Clinical trials used 40 mg a day, and the approved label is 40 mg a day. A 5 to 10 mg gray-market protocol is cost-driven underdosing, so you are paying $200 to $500 a month for a quarter of the studied dose. |
| The difference | SS-31 costs roughly $100 to $300 more a month | SS-31 runs about two to three times MOTS-c's monthly cost, and the gap widens if you try to reach the studied dose. At 40 mg a day you are multiplying the gray-market figure four to eight times, which puts it out of range for most people paying cash.MOTS-c is cheaper for a blunter reason: nobody knows what dose is right, so the community settled on one that is affordable. Neither price buys you human interventional efficacy evidence for the use case you have in mind. |
When to Switch
Both onset figures are estimates, so treat them as planning numbers rather than facts. MOTS-c gives a first noticeable change around week 1 with an 8-week assessment window and full effect at 8 weeks. SS-31 is slower: first noticeable around week 4, full effect and assessment window both at 12 weeks. That means a fair MOTS-c trial is two months and a fair SS-31 trial is three, and quitting SS-31 at week 6 tells you nothing.
Move from SS-31 to MOTS-c when the target is metabolic: fasting glucose, insulin resistance, body composition or the exercise-adaptation gap you cannot close through training. MOTS-c holds blood sugar 6.0 against 2.5 and body composition 5.5 against 2.5, and it costs less. Move from MOTS-c to SS-31 when the target is the organelle itself or a documented mitochondrial pathology, since SS-31 holds mitochondrial 8.5 against 6.5 and is the only one of the two with human trials, approval and a defined responder population.
Running them in sequence is the more defensible pattern than running them together, since their mechanisms do not overlap and no study has tested the combination. Two things stop the switch regardless of your goal: tested athletes cannot use MOTS-c at all, because WADA prohibits it under S4.4 as an AMPK activator, and neither peptide is appropriate in pregnancy or nursing.
Who Should Pick What?
Insulin-resistant adult who cannot train enough to fix it
MOTS-c
Blood sugar 6.0 against 2.5 and metabolic health 6.0 against 3.0, plus half the monthly cost. Understand what you are buying: Lee 2015 is a mouse study and Zhou 2024 measures blood levels rather than testing injections. Exhaust the proven metabolic interventions first, because this one has no human efficacy trial.
Diagnosed Barth syndrome patient over 30 kg
SS-31 (Elamipretide)
This is the only population with an approved drug and a real prescription path. Forzinity got FDA accelerated approval in September 2025 on knee extensor muscle strength as an intermediate endpoint, and Thompson 2024 followed patients out to 168 weeks. Go through a mitochondrial disease specialist, not a peptide vendor.
Adult with documented mitochondrial dysfunction on testing
SS-31 (Elamipretide)
Mitochondrial subrating 8.5 against 6.5, and SS-31 is the peptide aimed at the organelle rather than at the signaling around it. Temper the expectation with MMPOWER-3, which gave 218 patients 40 mg a day for 24 weeks and missed both the walk test and the fatigue endpoint. Karaa 2024's post hoc work suggests genotype-defined responders exist.
Drug-tested athlete of any kind
SS-31 (Elamipretide)
MOTS-c is named by WADA as an example of a prohibited AMPK activator under S4.4 metabolic modulators, so it is a hard stop rather than a risk to manage. SS-31's athlete status needs a GlobalDRO or anti-doping authority check rather than an assumption. In-competition tested sport is a listed contraindication on the MOTS-c report.
Dry age-related macular degeneration
SS-31 (Elamipretide)
The eye-vision subratings are 5.0 against 1.0, and the honest framing is that ReCLAIM-2 missed its primary endpoints in 176 patients. What survived were exploratory ellipsoid-zone and low-luminance letter-gain signals, with common injection-site reactions. This is a reason to watch the next trial, not a reason to inject yourself.
Healthy person chasing more energy and better aging
Tie
Neither, on current evidence. The SS-31 report says outright that it is a weak fit for healthy longevity users without measured mitochondrial impairment, and the MOTS-c report says its own strongest data is still mouse work. Both are injectables with no approved product for you, no dosing standard and no human efficacy trial in this population.
Heart failure with reduced ejection fraction
Tie
Neither. Butler 2020 gave 71 patients 4 mg or 40 mg daily for 28 days with no improvement in left ventricular volume or ejection fraction, and Daubert 2017's favorable acute infusion signal in 36 patients did not carry forward. MOTS-c has no cardiovascular trial. This is a row where the subrating gap points at evidence that already failed.
Pregnant, nursing, or planning either
Tie
Neither, and this is not a judgment call. Pregnancy and lactation are listed contraindications on both reports, and SS-31 adds a benzyl alcohol neonatal warning from the Forzinity label. There is no human exposure data in pregnancy for either peptide.
Research Highlights
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Mechanism Difference
These two mechanisms are complementary, with no meaningful overlap. MOTS-c is a 16-amino-acid peptide encoded in mitochondrial DNA. It inhibits ATIC in the folate and purine pathway, AICAR accumulates, AMPK activates, and the peptide can translocate to the nucleus under metabolic stress to change gene expression. It is a signaling molecule that happens to come from the mitochondrion.SS-31 never leaves the organelle. It binds cardiolipin on the inner mitochondrial membrane, holds cristae architecture together, keeps the electron transport chain supercomplexes organized and cuts the ROS leak. One changes the instructions. The other repairs the machine.
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Safety Comparison
SS-31 has the better-characterized safety profile because it has actually been given to people. Trials report injection-site redness, induration, itching, bruising, hives and pain, plus headache, dizziness and nausea, and the Forzinity label contraindicates serious hypersensitivity and warns about benzyl alcohol in neonates. Peripheral neuropathy under workup is a listed stop.MOTS-c's downside safety score is 1.3 out of 5.0, which reflects a benign preclinical signal rather than human safety data. The FDA flags compounded MOTs-C for immunogenicity, peptide impurities and missing human exposure data. Unknown is not the same as safe.
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Cost Comparison
MOTS-c runs $100 to $200 a month at 5 to 10 mg three times weekly, and SS-31 runs $200 to $500 a month at 5 to 10 mg daily. Both figures were extracted from the source reports on 2026-09-07 from the research-vendor channel, not estimated. Neither includes syringes, bacteriostatic water or cold-chain shipping.The SS-31 figure hides a dosing problem. Every clinical trial and the approved Forzinity label use 40 mg a day, so a gray-market 5 to 10 mg protocol is cost-driven underdosing. You are paying two to three times the MOTS-c price for a fraction of the dose anyone has studied.
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Editorial Verdict
MOTS-c scores 6.5 and SS-31 6.0, and the more useful fact is that no trial has ever compared them. Neither report contains a head-to-head study, so every row here is inference from separate and thin evidence. MOTS-c wins the metabolic column on mouse data and blood-level observations. SS-31 wins the mitochondrial and eye columns on human trials that mostly missed their primary endpoints.Buy MOTS-c if metabolic dysfunction is measured and training alone is not closing it. Buy SS-31 if mitochondrial pathology is documented. Buy neither if you are healthy and curious.
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Evidence Asymmetry
These two peptides fail their evidence tests in opposite directions, and the difference matters when you are deciding. MOTS-c has no published human interventional efficacy trial at all. Its strongest data is mouse work in Lee 2015 and Kim 2018, plus human observational studies of natural blood levels. Nothing has been disproven because nothing has been properly tested.SS-31 has 20-plus registered studies and multiple RCTs, and several missed: MMPOWER-3 in mitochondrial myopathy, ReCLAIM-2 in dry AMD, PROGRESS-HF in heart failure. A tested-and-missed record is more informative than an untested one, even when it looks worse.
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Floor Scores
Many subratings in this comparison sit at 1.0, and that number does not mean what it looks like. A 1.0 is the floor of the scale, assigned when no scored evidence exists for that use case. MOTS-c carries 1.0 across cognition, memory, sleep, mood, immune function and dozens of others.That is an absence of study, not a finding of failure. It also means a comparison row where both sides sit at 1.0 is worthless: neither peptide has been examined there, and picking a winner would be inventing one. Every row in the matrix above has at least one side carrying a real score.
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Durability
Neither peptide banks anything. MOTS-c scores 1.8 out of 5.0 on durability and SS-31 2.7, so the effect tracks the injections. Both also score low on dependency, which is the good news: stopping either is uneventful, and MOTS-c's reversibility score of 1.2 is close to the best available.What that means in practice is a cycle, not a habit. Neither report frames indefinite daily injection as the plan, and for SS-31 the daily subcutaneous burden plus injection-site reactions is the reason most people stop before the 12-week window closes.
Frequently Asked Questions
- Is MOTS-c or SS-31 better?
- MOTS-c scores 6.5 and SS-31 6.0, and the goal decides. MOTS-c takes blood sugar 6.0 against 2.5, body composition 5.5 against 2.5 and metabolic health 6.0 against 3.0. SS-31 takes mitochondrial 8.5 against 6.5, antioxidant 6.0 against 1.0 and eye vision 5.0 against 1.0. No study has compared them directly.
- Can I run MOTS-c and SS-31 together?
- The mechanisms do not overlap, so stacking them is not redundant. No study has tested the combination, in humans or animals, so there is no dosing guidance and no safety data for the pair.Running them in sequence is more defensible than running them at once, because you can tell which one did something. Combined, you are paying $300 to $700 a month for two injectables with no human efficacy trial between them.
- Why is SS-31 approved if the trials failed?
- Because it works in one specific disease. Forzinity received FDA accelerated approval on September 19, 2025 for Barth syndrome, where cardiolipin remodeling is genetically disrupted, so the drug's target is the actual defect.Outside that population, the record is different. MMPOWER-3 missed in mitochondrial myopathy, ReCLAIM-2 missed in dry AMD, and PROGRESS-HF missed in heart failure. Approval for one disease is not evidence for the others.
- Is the 5 to 10 mg gray-market SS-31 dose enough?
- Probably not. Every clinical trial and the approved Forzinity label use 40 mg a day subcutaneous. Gray-market protocols run 5 to 10 mg a day, which the source report calls cost-driven underdosing. You are taking a quarter of the studied dose or less, and nobody has tested whether that dose does anything at all.
- Why do so many use cases score 1.0?
- Because 1.0 is the floor of the scale, used when no scored evidence exists for that use case. MOTS-c carries 1.0 across cognition, memory, sleep, mood, immune function and dozens more. That is an absence of study, not a tested failure. It also means comparing the two on a use case where both sit at 1.0 would be inventing a winner out of nothing.
- How long before I know if either is working?
- Both onset figures are estimates rather than measured, so plan loosely. MOTS-c has an 8-week assessment window with a first noticeable change around week 1. SS-31 has a 12-week window with first noticeable around week 4. Judge MOTS-c at 8 weeks and SS-31 at 12, against something measurable: fasting glucose, body composition, a walk test.
- Can tested athletes use either one?
- Not MOTS-c. WADA names it as an example of a prohibited AMPK activator under S4.4 metabolic modulators, and in-competition tested sport is a listed contraindication on its report. SS-31's athlete status is less clear and needs a GlobalDRO or anti-doping authority check rather than an assumption that silence means permitted.
- Who should not use either one?
- Anyone pregnant or nursing, on both reports. MOTS-c additionally rules out active cancer with mitochondrial or metabolic vulnerability, medically complex polypharmacy without clinician oversight, and any vial with no third-party certificate of analysis.SS-31 additionally rules out serious hypersensitivity to elamipretide, body weight under 30 kg, severe renal impairment without dose adjustment, peripheral neuropathy under workup, and neonates because of the benzyl alcohol excipient.
- Is there any human proof MOTS-c does anything when injected?
- No published human interventional efficacy trial has administered exogenous MOTS-c and measured clinical endpoints. The human data measures your own natural MOTS-c levels: Zhou 2024 pooled seven biomarker studies, and Reynolds 2021 showed exercise raises it. The closest regulated program is CB4211, a MOTS-c analog in phase 1, which is not the same molecule.
Evidence Sources
- Preclinical The mitochondrial-derived peptide MOTS-c promotes metabolic homeostasis and reduces obesity and insulin resistance (2015) Discovery paper. MOTS-c is encoded in mitochondrial 12S rRNA, activates AMPK through the folate and purine pathway, and reduced obesity and insulin resistance in mice.
- Preclinical The mitochondrial-encoded peptide MOTS-c translocates to the nucleus to regulate nuclear gene expression in response to metabolic stress (2018) AMPK-dependent nuclear translocation and stress-response gene regulation. The mechanistic basis for calling MOTS-c a retrograde signaling peptide.
- Preclinical MOTS-c is an exercise-induced mitochondrial-encoded regulator of age-dependent physical decline and muscle homeostasis (2021) Exercise raises endogenous MOTS-c in humans, and MOTS-c affected physical capacity in mice. Not evidence that injecting it reproduces the adaptation.
- Meta-analysis The correlation between mitochondrial derived peptide and metabolic states: systematic review and meta-analysis (2024) Seven human biomarker studies: lower MOTS-c in the diabetes subgroup, with the obesity subgroup pointing the other way after analysis.
- Observational The mitochondrial-derived peptide MOTS-c: a player in exceptional longevity? (2015) The K14Q variant is associated with exceptional longevity in a Japanese population. A genetics association, not evidence that dosing MOTS-c extends life.
- RCT MMPOWER-3 randomized clinical trial of elamipretide in primary mitochondrial myopathy (2023) 218 patients: 40 mg a day subcutaneous for 24 weeks did not improve the 6-minute walk test or fatigue versus placebo.
- RCT Genotype-specific post hoc analysis of MMPOWER-3 (2024) Post hoc analysis of the 218-patient parent trial: genotype-defined subgroups showed a walk-test signal, supporting enrichment rather than broad efficacy.
- RCT ReCLAIM-2 randomized phase II trial of elamipretide in dry age-related macular degeneration (2024) 176 randomized: missed primary endpoints for low-luminance acuity and geographic atrophy area, with exploratory ellipsoid-zone and letter-gain signals. Injection-site reactions common.
- RCT PROGRESS-HF phase 2 trial of elamipretide in heart failure with reduced ejection fraction (2020) 71 patients: 4 mg or 40 mg daily for 28 days was well tolerated but did not improve left ventricular end-systolic volume or ejection fraction.
- Regulation FDA accelerated approval of Forzinity for Barth syndrome (2025) Accelerated approval granted September 19, 2025 for Barth syndrome patients weighing at least 30 kg, based on knee extensor muscle strength as an intermediate endpoint.
- Label Forzinity prescribing information, elamipretide label (2025) 40 mg once daily subcutaneous, renal dose reduction, serious hypersensitivity contraindication, benzyl alcohol neonatal warning, common injection-site reactions.
- Preclinical SS-31 re-energizes ischemic mitochondria by interacting with cardiolipin (2013) SS-31 binds cardiolipin, protects cristae membranes and accelerates ATP recovery after ischemia in preclinical kidney models.
- Preclinical SS-31 improves mitochondrial energetics and skeletal muscle performance in aged mice (2013) Rapid restoration of in vivo mitochondrial energetics toward young levels in aged mice.
- Observational Long-term efficacy and safety of elamipretide in Barth syndrome, 168-week extension (2024) 168-week open-label extension of TAZPOWER on 40 mg a day subcutaneous elamipretide in Barth syndrome.
- Regulation FDA list of bulk drug substances for compounding that may present significant safety risks (2026) Lists MOTs-C with immunogenicity, peptide impurity, API characterization and lack-of-human-exposure concerns.
- Guideline WADA Prohibited List, S4.4 metabolic modulators (2026) Names MOTS-c as an example of a prohibited AMPK activator. A hard stop for tested athletes.
- Guideline Mitochondrial Medicine Society patient care standards for primary mitochondrial disease (2017) Consensus standards emphasize supportive and organ-specific management. No broad society endorsement of SS-31 for general mitochondrial dysfunction.
- Trial registry CB4211 phase 1a/1b study in NASH and obesity (2020) The closest regulated MOTS-c analog program. Not direct evidence for exogenous MOTS-c efficacy.
Glossary
Quick reference for the medical and technical terms used in this comparison.
- AMPK AMP-Activated Protein Kinase
- The cell's low-fuel switch. Exercise and fasting turn it on, and it shifts cells toward burning fuel rather than storing it. MOTS-c activating it is why it is called an exercise mimetic.
- ATIC Aminoimidazole Carboxamide Ribonucleotide Formyltransferase
- An enzyme in the folate and purine pathway. MOTS-c inhibits it, AICAR builds up, and AMPK switches on. That is the whole mechanism chain.
- AICAR 5-Aminoimidazole-4-Carboxamide Ribonucleotide
- The molecule that accumulates when MOTS-c blocks ATIC. It is a direct AMPK activator, which is how a peptide ends up mimicking exercise.
- Cardiolipin Cardiolipin
- A fat unique to the inner mitochondrial membrane that holds cristae folds and energy-producing complexes in shape. SS-31 binds it, which is the entire basis of the drug.
- Cristae Cristae
- The folds of the inner mitochondrial membrane where ATP is made. More surface area means more energy production, and the folds collapse when cardiolipin is damaged.
- MDP Mitochondrial-Derived Peptide
- A small protein encoded by mitochondrial DNA rather than the cell nucleus. MOTS-c is one, alongside humanin and the SHLPs.
- ROS Reactive Oxygen Species
- Unstable oxygen molecules that leak from mitochondria and damage nearby structures. SS-31's antioxidant case is cutting the leak rather than mopping up afterward.
- 6MWT Six-Minute Walk Test
- How far someone walks in six minutes. The functional endpoint MMPOWER-3 used, and missed, in primary mitochondrial myopathy.
- PMM Primary Mitochondrial Myopathy
- Muscle weakness caused by genetic mitochondrial defects. The population where SS-31's largest trial, MMPOWER-3, failed its co-primary endpoints.
- COA Certificate of Analysis
- A third-party lab report on a vial's identity and purity. Both reports make it a hard requirement, because research-vendor peptides come with no regulatory guarantee.
