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SS-31 Results: What Studies Measured and When

What published studies measured for SS-31, when those outcomes were measured, and what is still unproven.

Medically reviewed by Juan Pablo Frías, MD · · DisclosureMitochondria-targeting peptideUpdated

What studies measured

Each outcome below comes from a published study, with its type and size, strongest design first. Animal and cell results are labelled as such and are not human results.

SS-31 outcomes in published studies
OutcomeResultStudy typeSource
Primary endpoints (low-luminance BCVA, GA growth)Primary endpoints were not met; a secondary imaging measure (ellipsoid zone loss) progressed 43% less than placebo (nominal P = 0.0034).Human RCTn = 176Ophthalmology science 2025, PMID 39605874
6MWT in CPEO subgroup (post hoc)In a post hoc subgroup with CPEO, walk distance changed by 37.3 m on elamipretide versus -8.0 m on placebo (p = 0.0024).Human RCTOrphanet journal of rare diseases 2024, PMID 39574155
6-minute walk and fatigue at week 24The pivotal randomized trial did not meet its primary endpoints (6-minute walk and fatigue score).Human RCTn = 218Neurology 2023, PMID 37268435
Walk distance differenceWalk distance difference versus placebo was -3.2 m (p = 0.69).Human RCTn = 218Neurology 2023, PMID 37268435
Primary endpoints (6MWT, BTHS-SA) in part 1Neither primary endpoint was met in the randomized crossover part.Human RCTn = 12Genetics in medicine 2021, PMID 33077895
Open-label extension, 36 weeksIn the uncontrolled extension at 36 weeks, 6-minute walk improved by 95.9 m and symptom score fell by 2.1 points.Human RCTn = 12Genetics in medicine 2021, PMID 33077895
Muscle mitochondrial capacityMitochondrial capacity rose right after a single 2-hour infusion (P = 0.055 and P = 0.045); the abstract reports no difference one week later.Human RCTn = 39PloS one 2021, PMID 34264994
Fatigue resistanceNo significant effect on muscle fatigue resistance.Human RCTn = 39PloS one 2021, PMID 34264994
6-minute walkWalk distance was 19.8 m longer on elamipretide (398.3 vs 378.5 m), not statistically significant (P = 0.0833).Human RCTn = 30Journal of cachexia, sarcopenia and muscle 2020, PMID 32096613
Fatigue symptomsPatient-reported fatigue and muscle complaints were lower on elamipretide (P = 0.0006 and P = 0.0018).Human RCTn = 30Journal of cachexia, sarcopenia and muscle 2020, PMID 32096613
6-minute walk after 5 daysHighest-dose participants walked 64.5 m farther versus 20.4 m for placebo at day 5 (p = 0.053).Human RCTn = 36Neurology 2018, PMID 29500292
Left ventricular volumesHighest dose reduced LV end-diastolic volume by 18 mL and end-systolic volume by 14 mL versus placebo at end of infusion.Human RCTn = 36Circulation. Heart failure 2017, PMID 29217757
6-minute walk at week 168Walk distance improved at every extension time point, by a cumulative 96.1 m at week 168.Human uncontrolled trialn = 10Genetics in medicine 2024, PMID 38602181
6-minute walk vs natural historyTreated patients walked 79.7 m further at week 64 and 91.0 m further at week 76 than natural-history controls.Human observationaln = 27Orphanet journal of rare diseases 2022, PMID 36056411
Muscle strength vs natural historyHandheld-dynamometry strength differed by 40.8 N at week 64 and 56.7 N at week 76 in favor of elamipretide.Human observationaln = 27Orphanet journal of rare diseases 2022, PMID 36056411
Skeletal muscle fibre typeElamipretide restored a near-normal skeletal muscle fibre-type composition in heart-failure dogs.Animal · dog (not a human result)n = 14ESC heart failure 2019, PMID 30688415
Cardiac function after MIEjection fraction was 55.3% with Bendavia versus 49.3% with water six weeks after infarction.Animal · rat (not a human result)n = 54Journal of cardiovascular pharmacology 2014, PMID 25165999
Mitochondrial functionElamipretide improved mitochondrial function in explanted failing human heart tissue.In vitro (not a human result)JACC. Basic to translational science 2019, PMID 31061916
  • Forzinity (elamipretide, also called SS-31, MTP-131 or Bendavia) is FDA-approved only for Barth syndrome in patients weighing at least 30 kg, under accelerated approval based on knee extensor muscle strength (an intermediate endpoint) with a confirmatory trial required; the label states FORZINITY was not superior to placebo on the randomized trial's primary endpoints (6-minute walk, total fatigue).
  • Barth syndrome evidence is tiny: 12 patients in TAZPOWER; the strength and walk gains come from the uncontrolled open-label extension and a natural-history comparison, not from the randomized period.
  • Primary mitochondrial myopathy (MMPOWER-3, n=218) failed its primary endpoints; MMPOWER-2 and the phase I/II trial showed non-significant or nominal signals. Dry AMD (ReCLAIM-2) also missed primary endpoints; reported benefits are secondary imaging measures with nominal P values.
  • No elimination half-life appears in the label (section 12.3 lists Tmax, bioavailability, volume of distribution and urinary recovery). A 2021 trial refers to the half-life of elamipretide in human blood being short enough that effect was gone by day 7 but gives no number.
  • No elamipretide trial for fibromyalgia was found in PubMed; fatigue evidence is from mitochondrial myopathy and Barth syndrome, not fibromyalgia.
  • Research-grade SS-31 sold online is not the same product as the Forzinity formulation (hydrochloride in benzyl-alcohol-preserved solution); the label's 40 mg daily dose is for Barth syndrome only.

Typical timeline

When measurable changes appeared in studies of SS-31: not reported in study abstracts (PubMed search, 2 Oct 2026).

Before-and-after photos

We don't publish before-and-after photos. They can't be verified, rarely show dose, diet or other drugs, and only the most dramatic results get posted.

Common questions

How long does SS-31 take to work?

The study abstracts we summarised for SS-31 do not report when outcomes were measured (PubMed search, 2 Oct 2026).

Do you show SS-31 before and after photos?

No. Photos can't be verified, rarely show dose, diet or other drugs, and only the most dramatic ones get posted. We summarize measured outcomes instead.

More on SS-31

DosageDoses used in published studies, with the source for each.CalculatorVial, water and dose to syringe units.Side effectsWhat labels and studies report, and what is unknown.PricePrice per mg and per week from dated listings. No vendor links.Legal statusFDA, compounding and WADA status with dates.50 mg vialConcentration and unit tables for the 50 mg size.

Sources

  1. 1ReCLAIM-2: A Randomized Phase II Clinical Trial Evaluating Elamipretide in Age-related Macular Degeneration, Geographic Atrophy Growth, Visual Function, and Ellipsoid Zone Preservation.Ophthalmology science · 2025PMID 39605874Accessed 2 Oct 2026
  2. 2Genotype-specific effects of elamipretide in patients with primary mitochondrial myopathy: a post hoc analysis of the MMPOWER-3 trial.Orphanet journal of rare diseases · 2024PMID 39574155Accessed 2 Oct 2026
  3. 3Efficacy and Safety of Elamipretide in Individuals With Primary Mitochondrial Myopathy: The MMPOWER-3 Randomized Clinical Trial.Neurology · 2023PMID 37268435Accessed 2 Oct 2026
  4. 4A phase 2/3 randomized clinical trial followed by an open-label extension to evaluate the effectiveness of elamipretide in Barth syndrome, a genetic disorder of mitochondrial cardiolipin metabolism.Genetics in medicine : official journal of the American College of Medical Genetics · 2021PMID 33077895Accessed 2 Oct 2026
  5. 5In vivo mitochondrial ATP production is improved in older adult skeletal muscle after a single dose of elamipretide in a randomized trial.PloS one · 2021PMID 34264994Accessed 2 Oct 2026
  6. 6A randomized crossover trial of elamipretide in adults with primary mitochondrial myopathy.Journal of cachexia, sarcopenia and muscle · 2020PMID 32096613Accessed 2 Oct 2026
  7. 7Randomized dose-escalation trial of elamipretide in adults with primary mitochondrial myopathy.Neurology · 2018PMID 29500292Accessed 2 Oct 2026
  8. 8Novel Mitochondria-Targeting Peptide in Heart Failure Treatment: A Randomized, Placebo-Controlled Trial of Elamipretide.Circulation. Heart failure · 2017PMID 29217757Accessed 2 Oct 2026
  9. 9Long-term efficacy and safety of elamipretide in patients with Barth syndrome: 168-week open-label extension results of TAZPOWER.Genetics in medicine : official journal of the American College of Medical Genetics · 2024PMID 38602181Accessed 2 Oct 2026
  10. 10Natural history comparison study to assess the efficacy of elamipretide in patients with Barth syndrome.Orphanet journal of rare diseases · 2022PMID 36056411Accessed 2 Oct 2026
  11. 11Effects of elamipretide on skeletal muscle in dogs with experimentally induced heart failure.ESC heart failure · 2019PMID 30688415Accessed 2 Oct 2026
  12. 12Bendavia, a mitochondria-targeting peptide, improves postinfarction cardiac function, prevents adverse left ventricular remodeling, and restores mitochondria-related gene expression in rats.Journal of cardiovascular pharmacology · 2014PMID 25165999Accessed 2 Oct 2026
  13. 13Elamipretide Improves Mitochondrial Function in the Failing Human Heart.JACC. Basic to translational science · 2019PMID 31061916Accessed 2 Oct 2026
  14. 14PubMed search: (elamipretide[tiab] OR Bendavia[tiab] OR "MTP-131"[tiab] OR Forzinity[tiab] OR (("SS-31"[tiab] OR SS31[tiab]) AND (peptide*[tiab] OR mitochondri*[tiab] OR cardiolipin[tiab] OR Szeto[tiab]))) (526 results)PubMed · 2026pubmed.ncbi.nlm.nih.govAccessed 2 Oct 2026
  15. 15PubMed search: (elamipretide[tiab] OR Bendavia[tiab] OR "MTP-131"[tiab] OR Forzinity[tiab] OR (("SS-31"[tiab] OR SS31[tiab]) AND (peptide*[tiab] OR mitochondri*[tiab] OR cardiolipin[tiab] OR Szeto[tiab]))) AND (randomized[tiab] OR trial[tiab] OR patients[tiab]) (133 results)PubMed · 2026pubmed.ncbi.nlm.nih.govAccessed 2 Oct 2026
  16. 16PubMed search: (elamipretide[tiab] OR Bendavia[tiab] OR "MTP-131"[tiab] OR Forzinity[tiab] OR (("SS-31"[tiab] OR SS31[tiab]) AND (peptide*[tiab] OR mitochondri*[tiab] OR cardiolipin[tiab] OR Szeto[tiab]))) AND (half-life[tiab] OR pharmacokinetic*[tiab]) (11 results)PubMed · 2026pubmed.ncbi.nlm.nih.govAccessed 2 Oct 2026
  17. 17PubMed search: elamipretide[tiab] AND (TAZPOWER[tiab] OR "Barth syndrome"[tiab]) AND (randomized[tiab] OR crossover[tiab]) (6 results)PubMed · 2026pubmed.ncbi.nlm.nih.govAccessed 2 Oct 2026
  18. 18PubMed search: elamipretide[tiab] AND (macular[tiab] OR "geographic atrophy"[tiab]) (9 results)PubMed · 2026pubmed.ncbi.nlm.nih.govAccessed 2 Oct 2026
  19. 19PubMed search: elamipretide[tiab] AND (fibromyalgia[tiab] OR fatigue[tiab] OR "chronic pain"[tiab]) (19 results)PubMed · 2026pubmed.ncbi.nlm.nih.govAccessed 2 Oct 2026

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