Pinc PeptideThe girly peptide research blog

SS-31 (elamipretide) · Dose evidence · updated 8 October 2026

SS-31 dosage: what studies actually used

The short answer

SS-31 is the research code for elamipretide, the drug in Forzinity171819. The Forzinity label sets one dose, 40 mg injected under the skin once a day, for adults and children with Barth syndrome who weigh at least 30 kg, and halves it to 20 mg a day for adults with severe kidney impairment who are not on dialysis18. No dose is approved for any other use, and even for Barth syndrome FDA’s reviewers wrote that ‘it is not clear that the studied dose of 40 mg SC is the optimal dose’182021. This page reports those doses and is not dosing advice.

Not dosing advice. This page reports doses that studies and approved labels used, with their sources. It does not recommend a dose, and we do not give mixing, injection or unit-conversion instructions. Gray-market vials often do not contain what their label says. How we report doses.

Every dose studied in people

StudyWhoPeopleDose and routeWhat happened
EMBRACE STEMI (Gibson 2016), Phase 2a randomized placebo-controlled trial Adults with a first anterior STEMI, a major heart attack, treated by angioplasty to reopen the artery 300 0.05 mg/kg/hour, or placebo
IV infusion · From 15 to 60 minutes before angioplasty until 1 hour after blood flow was restored		 Heart damage, measured by the enzyme CK-MB over 72 hours, was 5570 ± 486 ng h/mL on elamipretide and 5785 ± 426 on placebo, not a significant difference, and prespecified MRI, angiography, ECG and clinical outcomes did not improve; the paper called the drug safe and well tolerated22. The trial’s registry lists 10 deaths among 150 people on elamipretide and 3 among 147 on placebo, and serious cardiogenic shock in 4 against none23.
MMPOWER-3 (Karaa 2023), Phase 3 randomized placebo-controlled trial People with primary mitochondrial myopathy, a group of genetic muscle diseases 218 40 mg once daily, or placebo
Injection under the skin · 24 weeks		 It missed both main goals: walking distance changed by −3.2 m compared with placebo (p = 0.69), and the fatigue score did not improve (p = 0.37)24. Most adverse events were mild to moderate24.
ReCLAIM-2 (Ehlers 2025), Phase 2 randomized placebo-controlled trial Adults aged 55 or older with dry age-related macular degeneration and geographic atrophy (patches of retinal loss) 176 40 mg once daily, or placebo
Injection under the skin · 48 weeks		 It missed both main goals, low-light vision and growth of the atrophy, though a marker of light-sensing cell loss in the retina (the ellipsoid zone) progressed less on other prespecified measures, with nominal (unadjusted) P values25. Adverse events affected 86% on elamipretide and 71% on placebo, most often injection-site reactions25.
NuPower (SPIMD-301), Phase 3 randomized placebo-controlled trial Adults aged 18 to 70 with primary mitochondrial disease caused by changes in nuclear DNA 102 60 mg once daily, or placebo
Injection under the skin · 48 weeks		 It was completed on 4 December 2024, but no results had been posted on ClinicalTrials.gov as of 7 October 202626. FDA’s review reported injection-site redness in 51% versus 8% on placebo and 7 serious adverse events versus 1, none judged drug-related by the investigators or the company21. There was one death from cardiac arrest on elamipretide, which, the reviewers wrote, the evidence suggested was related to the person’s underlying conditions rather than the drug21.
PROGRESS-HF (Butler 2020), Phase 2 randomized placebo-controlled trial People with heart failure whose ejection fraction, the share of blood pumped out with each beat, was 40% or less 71 4 mg or 40 mg once daily, or placebo
Injection under the skin · 28 days		 Neither dose reduced the amount of blood left in the heart after each beat (end-systolic volume) more than placebo after 4 weeks (P = 0.90 for 4 mg; P = 0.28 for 40 mg)27. Rates of drug-related adverse events were similar in the three groups27.
SPICP-102 (in FDA’s review), randomized three-way crossover heart-rhythm (thorough QT) study Healthy adults aged 18 to 55 40 80 mg every 3 hours for five doses; placebo; or placebo plus one 400 mg dose of moxifloxacin by mouth as a positive control
Injection under the skin · One day for each regimen, in turn		 Average placebo-corrected QTcF changes were negative at every time point, from −0.3 to −4.7 milliseconds, which FDA’s reviewers called a negative thorough QT study21. Of 40 enrolled, 39 completed and were analyzed21.
SPIRI-101 (in FDA’s review), Phase 1 randomized placebo-controlled trial Healthy volunteers in five dose groups of 8 40 0.025, 0.05, 0.1, 0.25 or 0.5 mg/kg in one infusion, or placebo
IV infusion · One 4-hour infusion		 Exposure rose in proportion to the dose, and the drug was cleared quickly at every dose21. FDA’s reviewers noted that drug-level results from these infusions could not be generally applied to injections under the skin21.
MOTION (Roshanravan 2021), Phase 2 randomized placebo-controlled trial Healthy adults aged 60 to 85 with poorly functioning muscle mitochondria 39 0.25 mg/kg/hour, or placebo
IV infusion · One 2-hour infusion		 Right after the infusion, the maximum energy (ATP) production of mitochondria in a hand muscle rose relative to placebo (P = 0.055; P = 0.045 as a percentage change), but not on day 7, and fatigue resistance did not improve28. The registry lists 41 enrolled and no serious adverse events in either group29.
MMPOWER, SPIMM-201 (Karaa 2018), Phase 1/2 randomized placebo-controlled dose-escalation trial People aged 16 to 65 with primary mitochondrial myopathy 36 0.01, 0.10 or 0.25 mg/kg/hour for 2 hours once a day, or placebo
IV infusion · 5 days		 On the highest dose, walking distance rose 64.5 m by day 5 against 20.4 m on placebo (p = 0.053), and the gain rose with dose (p = 0.014), but 2 days after the last dose the highest-dose and placebo groups no longer differed (p = 0.387)2. There were no deaths, serious adverse events or dropouts for adverse events2.
Daubert 2017, randomized placebo-controlled ascending-dose trial People with heart failure and an ejection fraction of 35% or less 36 0.005, 0.05 or 0.25 mg/kg/hour, or placebo
IV infusion · One 4-hour infusion		 There were no serious adverse events, and blood pressure and heart rate stayed stable30. At the end of the infusion, only the highest dose reduced heart volumes compared with placebo (end-diastolic −18 mL, P = 0.009; end-systolic −14 mL, P = 0.005)30.
MMPOWER-2 (Karaa 2020), randomized placebo-controlled crossover trial Adults with primary mitochondrial myopathy 30 40 mg once daily, then placebo, or the reverse
Injection under the skin · 4 weeks on each, with a 4-week washout		 Walking distance was 398.3 m on elamipretide and 378.5 m on placebo, a 19.8 m difference that was not statistically significant (P = 0.0833), although fatigue scores improved (P = 0.0006)31. Injection-site reactions occurred in 80% on elamipretide, and there were no serious adverse events or deaths31.
MMPOWER-2 open-label extension, SPIMM-203 (NCT02976038) People aged 16 or older with primary mitochondrial myopathy who had completed MMPOWER-2 28 40 mg once daily
Injection under the skin · Planned for up to 260 weeks; stopped early		 It was terminated because, in the registry’s words, the registration trial ‘did not meet the primary end points’, and the registry counts none of the 28 as completing it, 22 of them because of a physician’s decision6. Average walking distance changed by +3.6 m at week 13 (28 people) and −54.0 m at the end-of-trial visit (19 people), with no placebo group or statistical analysis; 8 of 28 had serious adverse events and none died6.
SPIRI-154 (in FDA’s review), Phase 1 open-label kidney-function study Adults with normal kidney function or mild, moderate or severe kidney impairment, 6 per group 24 0.05 mg/kg/hour
IV infusion · One 4-hour infusion		 Essentially the whole infused dose was recovered in urine, 10% as elamipretide, 34% as M1 and 57% as M2, its two breakdown products21. Compared with normal kidney function, elamipretide exposure was 46%, 63% and 154% higher in mild, moderate and severe impairment, and M1 and M2 exposure 271% and 715% higher in severe impairment21.
SPICP-101 (in FDA’s review), Phase 1 open-label kidney-function study Adults with normal kidney function (6) or mild (6), moderate (6) or severe (5) kidney impairment 23 0.25 mg/kg/hour for 1 hour, once daily
IV infusion · 7 days		 After 7 days, elamipretide exposure was 39%, 75% and 125% higher in mild, moderate and severe impairment than with normal kidneys, and M1 and M2 exposure 278% and 640% higher in severe impairment21. M2 built up over the week in every group, most in severe impairment (413.5%)21.
SPIFD-101 (NCT02653391), Phase 1/2 randomized vehicle-controlled trial Adults with Fuchs’ corneal endothelial dystrophy, a disease of the cornea, in both eyes 22 Part A: 1.0% drops twice daily in one eye, dummy drops in the other; Part B: 3.0% or dummy drops twice daily in both eyes
Eye drops · Visits through week 16		 In Part A, 6 of 18 people had mild eye side effects in the treated eye and 3 of 18 in the dummy-drop eye; in Part B, 2 of the 3 given 3.0% drops had moderate eye side effects8. One person in Part A had a serious adverse event, 16 of 18 in Part A and 1 of 3 on 3.0% drops completed, and no efficacy analysis was posted8.
ReCLAIM high-risk drusen cohort (Allingham 2022), Phase 1 open-label trial Adults aged 55 or older with intermediate age-related macular degeneration and high-risk drusen 21 40 mg once daily
Injection under the skin · 24 weeks		 All 21 had at least one adverse event, all mild or moderate and most often at the injection site; one stopped because of an injection-site reaction, and one had a serious adverse event (a urinary stone) judged unrelated4. Among the 18 who finished, sharp vision improved by 3.6 letters on average (P = 0.014), with no placebo group4.
ReCLAIM noncentral geographic atrophy cohort (Mettu 2022), Phase 1 open-label trial Adults aged 55 or older with dry age-related macular degeneration and noncentral geographic atrophy 19 40 mg once daily
Injection under the skin · 24 weeks		 Two people left because of adverse events (one developed wet macular degeneration, one had an intolerable injection-site reaction); the abstract reports no serious adverse events, but the results list two in one person, judged unrelated5. Among the 15 who finished, sharp vision improved by 4.6 letters on average (P = 0.0032), with no placebo group5.
ELViS-FA (NCT05168774), Phase 1/2 randomized open-label pilot People older than 16 with Friedreich ataxia, an inherited nerve and heart disease, and reduced vision 16 20 to 30 mg or 40 to 60 mg once daily
Injection under the skin · 52 weeks		 Of 20 enrolled, 16 were treated and 8 completed; 2 people on the lower dose and none on the higher dose left because of adverse events9. Median change in sharp (high-contrast) vision was +5.5 letters on the lower dose (6 people) and 0 on the higher dose (7 people), with no statistical analysis posted, and 2 of 8 in each group had serious adverse events9.
EVOLVE (Saad 2017), Phase 2a randomized placebo-controlled pilot Adults aged 40 to 80 with narrowed kidney arteries (atherosclerotic renal artery stenosis) having a stent procedure 14 0.05 mg/kg/hour, or placebo
IV infusion · One infusion, started 30 minutes before the procedure, for at most 4 hours		 Blood flow to the stented kidney rose from 202 to 262 mL/min three months after the procedure (P = 0.04) in the elamipretide group only, a comparison with its own starting value rather than with placebo3. The registry’s main outcome, the change in measured kidney filtration at 8 weeks, was +6.3 mL/min on elamipretide and +12.0 mL/min on placebo with no statistical comparison posted7.
Leber hereditary optic neuropathy trial (Karanjia 2024), Phase 2 randomized vehicle-controlled trial Adults aged 18 to 50 with Leber hereditary optic neuropathy, an inherited cause of vision loss 12 One drop of 1% solution twice daily in one eye, with dummy drops in the other, or in both eyes
Eye drops · 52 weeks, then an open-label extension		 Change in sharp vision in treated eyes did not differ from dummy-treated eyes at any time point32. Most side effects were mild to moderate, and neither the paper nor the registry reports a serious adverse event1032.
TAZPOWER (Thompson 2021), randomized placebo-controlled crossover trial Males aged 12 to 35 with Barth syndrome 12 40 mg once daily, then placebo, or the reverse
Injection under the skin · 12 weeks on each, with a 4-week washout		 Neither main goal, the 6-minute walk test and a symptom score, was met in the randomized part33. Median knee strength changed by +4 newtons on elamipretide and −5 on placebo at week 12, and all 12 had injection-site redness on elamipretide against 3 of 12 on placebo18.
TAZPOWER open-label extension (Thompson 2024) Patients with Barth syndrome who completed TAZPOWER 10 40 mg once daily
Injection under the skin · 168 weeks		 Eight of the 10 reached week 168, and injection-site reactions were the most common adverse events34. At extension visits, median knee strength was 34 to 68 newtons above its level before the first dose (a median of 124 newtons), and walking distance rose by a cumulative 96.1 m at week 168 (P = .003), with no placebo group; FDA could attribute an effect only to knee strength182134.
SPICP-104 (in FDA’s review), Phase 1 open-label study Healthy volunteers 8 60 mg every 3 hours for five doses
Injection under the skin · One day		 Peak elamipretide levels after the fifth dose were about 1.6 times those after the first, and peak M1 and M2 levels about 5 and 20 times, although the first-dose peaks may have been underestimated21. FDA’s reviewers called the regimen ‘generally well-tolerated in healthy volunteers’21.
SPICP-105 (in FDA’s review), Phase 1 bioavailability study Healthy volunteers: 32 in a single-dose arm, 8 in a 7-day arm – A single 40 mg dose of each of two salt forms (acetate and hydrochloride); or 40 mg once daily
Injection under the skin · Single doses; 7 days		 The two salt forms gave comparable exposure21. In the 7-day arm, elamipretide’s average 24-hour exposure (AUC) was 4110 ng·h/mL on day 1 and 4200 on day 7, while that of M2 rose from 518 to 82821.
SPISC-101 (in FDA’s review), Phase 1 randomized placebo-controlled study Healthy volunteers: 47 in a single-dose part, 35 in a 7-day part – Single doses of 2, 6, 12, 20 or 40 mg, or placebo; or 6, 20 or 40 mg once daily, or placebo
Injection under the skin · Single doses; 7 days		 Exposure to elamipretide and M1 rose in proportion to the dose, while M2 rose more than in proportion after repeated doses and built up, because it is eliminated more slowly21.
SPISC-102 (in FDA’s review), Phase 1 randomized placebo-controlled study Healthy volunteers: 26 in a single-dose part, 25 in a 7-day part – 40 mg or 80 mg, or placebo, as single doses or once daily; FDA’s table leaves a third group’s dose blank
Injection under the skin · Single doses; 7 days		 Doubling the dose roughly doubled exposure21. After 7 days, M2’s half-life was 20.5 to 24.0 hours and it had accumulated, while elamipretide and M1 showed little or no build-up21.

The approved schedule (Forzinity (FDA label))

Forzinity is ‘indicated to improve muscle strength in adult and pediatric patients with Barth syndrome weighing at least 30 kg’18. Barth syndrome is a rare genetic disorder caused by defects in the TAZ gene, and it is not likely to affect females1833. This is an accelerated approval based on knee muscle strength, an intermediate measure, and continued approval may depend on a confirmatory trial showing clinical benefit18. The company announced on 8 July 2026 that the first patient had been dosed in that trial, 4TAZPower35. Safety and effectiveness have not been established in children who weigh less than 30 kg18. The steps below follow the label’s dosing section, with stop rules from its warnings and overdose sections; that label, revised in September 2025, was the only elamipretide label listed on DailyMed as of 7 October 2026118.

WhenDose on the labelNote
Each day (patients weighing at least 30 kg)40 mg under the skin (subcutaneously), once dailyAt the same time each day; the label calls 40 mg a day the maximum recommended human dose
Adults with eGFR of 30 mL/minute or higher40 mg once dailyeGFR is a blood-test estimate of how well the kidneys filter; mild (60 to 89) or moderate (30 to 59) kidney impairment needs no change
Adults with eGFR below 30 mL/minute, not on dialysis20 mg once dailySevere kidney impairment: the label reduces the dose by one half
Adults with eGFR below 30 mL/minute, on dialysisNo dose recommendedThe label cites insufficient information; Forzinity has not been studied in people with kidney failure on dialysis
Children weighing 30 kg or more with kidney impairmentNo dose recommendedThe label cites insufficient information
A missed doseSkip it and take the next dose at the scheduled timeThe label says not to take a double dose
A serious allergic (hypersensitivity) reactionNo further dosesThe label says to watch for allergic reactions, which may occur within minutes to months after starting, and not to restart after a serious one
Persistent or severe skin reactionsConsider stoppingFrom the label’s warning on hypersensitivity
Suspected overdoseInterrupt treatmentNo overdoses were reported in trials; signs would likely be histamine-related, such as low blood pressure or feeling faint

Studies, animals and users: kept apart

Doses below are what studies used or what a label says. They are not advice, and gray-market products may not contain what their label says.

In human studies

Approved label: 40 mg injected under the skin once daily; 20 mg once daily for people with severely reduced kidney function (eGFR below 30) who are not on dialysis, with too little information for people on dialysis18. Controlled trials of daily injections mostly used 40 mg for 4 to 48 weeks24253133; PROGRESS-HF compared 4 mg and 40 mg for 28 days27, and NuPower used 60 mg a day for 48 weeks26. Drips into a vein used 0.25 mg/kg/hour for 2 hours in MOTION28, 0.05 mg/kg/hour in EMBRACE STEMI, from 15 to 60 minutes before angioplasty until 1 hour after blood flow was restored23 and 0.005 to 0.25 mg/kg/hour for 4 hours in heart failure30. FDA’s review notes that multiple doses up to 80 mg a day have been tolerated21. The longest reported use is 168 weeks in 8 patients with Barth syndrome, 3 of whom reached 192 weeks18. In healthy people, only single doses and short safety studies have results; a 4-week pilot in older adults is still recruiting212837.

In animal studies

Old mice: one 3 mg/kg injection into the abdomen restored muscle energy measures within 1 hour, and 8 days of treatment increased endurance38. Old mice given 3 µg/g of body weight a day by a pump implanted under the skin for 8 weeks had better heart relaxation39, and another study gave 3 mg/kg a day by implanted pumps for 8 weeks40. Reproductive studies found no embryo-fetal toxicity at up to 10 mg/kg/day into a vein in rats and 50 mg/kg/day in rabbits, and no effect on rat fertility at up to 20 mg/kg/day under the skin18.

What users report Anecdotal · not validated · not a recommendation

A dosing-protocol website (updated 4 October 2026) lists 5 to 10 mg injected under the skin once a day, and up to 20 mg a day in an ‘advanced’ chart. The same page says a research vial is not interchangeable with the FDA-approved Forzinity36.

Half-life and how it is taken

Half-life
about 1.5 to 4 hours21After a single 40 mg injection under the skin, the mean half-life was 3.2 hours in 32 healthy volunteers and 1.5 hours in 7 patients with Barth syndrome; after 7 daily doses it was 2.8 hours in 5 volunteers, and FDA’s summary table gives about 3 to 4 hours21. Blood levels peak 0.5 to 1 hour after an injection, and nearly all of a dose is recovered in the urine, as the drug or its breakdown products, within 48 hours18.
Routes
  • Subcutaneous injection: the approved Forzinity route; human data from early safety studies to large trials
  • Intravenous infusion: single drips or short courses in heart, kidney-function and aging studies; human data
  • Eye drops: three small trials, of 1% drops in Leber hereditary optic neuropathy, 1% and 3% drops in Fuchs’ corneal dystrophy, and low- and high-dose drops in diabetic macular edema and macular degeneration; the Leber trial found no benefit, and the other two posted no efficacy results
  • By mouth: early safety and drug-level studies in healthy volunteers only
  • Gray-market ‘SS-31’ is sold as freeze-dried powder in vials; we found no human data on these products

Why the label uses one 40 mg dose

FDA’s reviewers wrote that the company based its choice of 40 mg ‘mainly on Study SPIMM-201’, a 5-day trial of daily drips into a vein in 36 people with primary mitochondrial myopathy21. The reviewers list its doses as 0.02, 0.20 and 0.50 mg/kg, and the published report as 0.01, 0.10 and 0.25 mg/kg/hour over 2 hours221. According to the reviewers, the top dose gave exposure similar to 40 mg under the skin, and it produced that trial’s largest walking gain, shown in the table above221.

The reviewers found a weak link between exposure and response in that trial, but ‘the variability in the response is large and the sample size was too small to make a definitive conclusion’21. MMPOWER-3, a larger trial of 40 mg a day, then showed no treatment effect, suggesting in their words ‘a lack of dose-response relationship up to a dose of 40 mg SC once daily’21. The company ‘did not conduct a dose ranging study in patients with Barth syndrome’, and the reviewers concluded that ‘there are no adequate data to demonstrate an exposure response relationship’ for that disease21.

The dose does not change with body weight, although weight changes exposure: in a model based on healthy volunteers, exposure was 26% higher at 55 kg and 22% lower at 105 kg than at 75 kg21. FDA’s reviewers based the 30 kg floor on the Barth syndrome trial, whose lightest patient weighed about 30 kg, and wrote that an age cutoff would have given 12-year-olds under 30 kg ‘the uniform 40 mg dose which is inappropriate for their weight’21.

As of 7 October 2026, no dose is approved for children who weigh less than 30 kg118. On 8 July 2026 the company said it planned to start a one-month safety and drug-level study that year ‘to verify dosing for children weighing less than 30 kilograms’, and 4TAZPower enrolls males aged 5 to 553541.

Why the label halves the dose for severe kidney impairment

The body breaks elamipretide down into two products, M1 and M2, which have no drug activity, and all three leave the body in urine18. FDA’s reviewers wrote that kidney impairment slows clearance and that ‘the effect is more pronounced on the metabolites, particularly M2’21. At 40 mg, M2 levels in severe impairment were expected to exceed what long-term toxicity studies in rats and dogs had covered, so the reviewers recommended halving the dose to 20 mg a day, which keeps elamipretide exposure like that of people with normal kidneys and brings M2 exposure within the range already tested in animals21.

Those estimates come from two small studies of drips into a vein, SPIRI-154 and SPICP-101 in the table above, where exposure rose with the severity of impairment and far more for M2 than for elamipretide21. The reviewers wrote that, apart from those two studies, all clinical trials had excluded people with an eGFR below 30, so the 20 mg dose rests on drug-level measurements, not on experience treating such patients21.

The later trials NuPower, ReNEW, SHAPE and 4TAZPower also exclude people with an eGFR below 3026374142.

What changed at higher doses

The label says elamipretide exposure rises in proportion to the dose from 2 to 80 mg a day, with little build-up18. M2 is different: in the healthy-volunteer studies in the table above, it rose more than in proportion to the dose and built up with repeated doses21.

Above the label’s 40 mg, healthy volunteers received up to 80 mg once a day for 7 days, and 80 mg every 3 hours for five doses in one day, which FDA’s reviewers wrote was given ‘without apparent safety concerns’21. That second regimen was meant to cover any level seen in patients taking 40 mg a day, and the label reports no clinically significant lengthening of the QTc interval, a heart-rhythm measure, at 3 times the peak level of the maximum recommended dose1821. In patients, NuPower gave 60 mg a day for 48 weeks and the Friedreich ataxia pilot up to 60 mg a day for 52 weeks, while the highest dose in Barth syndrome was 40 mg once daily92126.

Among the trials in the table that measured a benefit, these compared doses within the same study292730:

  • MMPOWER (5 days of drips): the walking-distance gain rose with dose, but 2 days after the last dose the highest-dose group no longer differed from placebo2.
  • Daubert’s heart failure study (one 4-hour drip): heart volumes fell only at the highest of three doses, measured at the end of the drip30.
  • PROGRESS-HF (28 days of injections): neither 4 mg nor 40 mg improved heart volume or pumping more than placebo27.
  • Friedreich ataxia pilot (52 weeks of injections): no statistical comparison of its two dose ranges was posted9.

Early on, a dose-limiting drop in blood sodium (hyponatremia) was seen in animals and in the first study in people, but FDA’s reviewers wrote that ‘the initial concern for hyponatremia was not borne out in subsequent clinical trials’21.

Which trials used amounts like those on dosing charts

The amounts on the dosing chart summarized under ‘What users report’ above are below the label’s 40 mg1836. Only a few studies in the table gave injections of less than 40 mg a day: SPISC-101 in healthy volunteers (6 or 20 mg a day for 7 days), PROGRESS-HF in heart failure (4 mg a day for 28 days) and the Friedreich ataxia pilot (20 to 30 mg a day for 52 weeks)92127. None of the three studied aging or energy, and the one in healthy people measured safety and drug levels, not benefit92127.

Where benefit was measured, 4 mg did no better than placebo on heart function in PROGRESS-HF, and the Friedreich ataxia pilot posted no statistical comparison between its dose groups927.

Why ‘SS-31’ research vials are not Forzinity

The label’s doses describe Forzinity, a sterile, ready-to-use solution of 80 mg/mL, while ‘SS-31’ sold online is a freeze-dried powder labeled for research use only1843.

On 24 August 2026 FDA warned four online sellers that the ‘SS-31’ they sold was an unapproved new drug, and each letter says that, despite ‘research use only’ labels, the seller’s website showed the products were intended as drugs for human use, as the legal tracker records44454647.

What is in the vials also varies: of 20 tests of gray-market ‘SS-31’ reported by the testing service Finnrick between March and September 2026, 12 passed, 5 failed and 3 were incomplete, against a standard of at least 99.5% purity and content within 35% of the label, as the SS-31 review details48. Under that standard, a vial can pass while holding up to 35% more or less than its label says, and the results include no sterility testing48. Health Canada warns that unauthorized injectable peptides may contain too much, too little or none of the active ingredient49.

Trials with no posted results

Older registry records call the drug MTP-131 or Bendavia, earlier names for elamipretide50. As of 7 October 2026, these completed trials had posted no results on ClinicalTrials.gov11121314151626:

  • NuPower (table above): 60 mg a day for 48 weeks, completed on 4 December 2024; FDA’s review reported only its safety data2126.
  • 20 mg into a vein once a day for 7 days, or placebo, in 308 adults hospitalized with congestion due to heart failure; completed on 27 November 201711.
  • 40 mg under the skin once a day for 28 days, or placebo, in 46 adults aged 40 to 80 with heart failure with preserved ejection fraction; completed on 2 June 201712.
  • Single capsules of 10, 50 or 100 mg, or placebo, in 30 healthy volunteers; completed in February 201313.
  • Capsules of 10 or 50 mg, or placebo, once a day for 7 days in 30 healthy volunteers; completed in March 201314.
  • Low- or high-dose eye drops twice a day in 20 people with diabetic macular edema or intermediate age-related macular degeneration, without a placebo group; completed in June 201515.
  • A 4-hour drip of 0.25 mg/kg/hour and, in a separate period, a saline drip, in 6 healthy men who smoked one cigarette during each drip; completed in March 201216.

Three more were under way as of 7 October 2026374142:

  • 4TAZPower, the confirmatory trial in Barth syndrome: once-daily injections or placebo for 72 weeks in an estimated 48 males aged 5 to 55; the registry does not state the dose, and its primary completion is estimated for 30 September 20293541.
  • ReNEW: 40 mg or placebo, 2 to 1, under the skin once a day for 96 weeks in 313 people aged 55 or older with dry age-related macular degeneration; no longer recruiting, with primary completion estimated for August 202742. FDA’s review reported that, as of 9 May 2025, its data remained blinded, with no deaths or related serious adverse events and two dropouts for injection-site reactions21.
  • SHAPE: daily injections for 4 weeks in about 30 healthy adults aged 65 to 80, in a single group with no dose stated; still listed as recruiting at its last update on 10 December 2025, although its estimated completion date of 15 April 2026 has passed37.

Questions people ask

How much SS-31 should I take?

No SS-31 dose is established for anti-aging, energy or any use other than Barth syndrome, the only use FDA has approved, as Forzinity1820. For that disease the label sets 40 mg injected under the skin once a day for patients who weigh at least 30 kg, and FDA’s reviewers noted that the larger trials in other conditions did not show a treatment effect on clinical outcomes1821. Ask a prescriber whether any dose fits you.

What is the dose of Forzinity?

The label’s dose is 40 mg under the skin once a day at the same time each day, which it also calls the maximum recommended human dose; a missed dose is skipped, not doubled18. For adults with severe kidney impairment who are not on dialysis the label halves it to 20 mg a day, and no dose is set for children under 30 kg18.

What is the highest dose of SS-31 tested in people?

Injected under the skin, healthy volunteers received up to 80 mg once a day for 7 days, and 80 mg every 3 hours for five doses in a heart-rhythm study, which FDA’s reviewers wrote was given ‘without apparent safety concerns’21. In patients, NuPower gave 60 mg a day for 48 weeks, and the highest dose given in Barth syndrome was 40 mg a day2126.

Does kidney disease change the SS-31 dose?

On the Forzinity label, yes: for adults with an eGFR below 30 mL/minute who are not on dialysis the dose is 20 mg a day instead of 40 mg, and mild or moderate impairment needs no change18. The label sets no dose for people on dialysis or for children with kidney impairment, and apart from two small drug-level studies, trials excluded people with severe impairment1821.

How long did SS-31 trials last?

Trials with a placebo comparison ran from a single drip into a vein to 48 weeks of daily injections, and to 52 weeks for eye drops compared with dummy drops in Leber hereditary optic neuropathy22252632. Without a placebo, the TAZPOWER extension in Barth syndrome reached 168 weeks, while an extension in mitochondrial myopathy planned for up to 260 weeks was stopped early because the registration trial ‘did not meet the primary end points’634. The ongoing ReNEW and 4TAZPower trials are planned to last 96 and 72 weeks4142.

Can you take SS-31 by mouth or as eye drops?

Neither form is approved: Forzinity is an injection under the skin, and its label says it is not approved for use into a vein either18. Capsules of 10, 50 or 100 mg were tested only in healthy volunteers in 2012 and 2013, with no results posted1314. Eye drops were tested in three small trials, at 1% in Leber hereditary optic neuropathy, at 1% and 3% in Fuchs dystrophy and at unstated strengths in diabetic macular edema and macular degeneration, and the Leber trial found no difference in sharp vision against dummy drops81532.

Go deeper

Sources

  1. 1DailyMed search results for elamipretide U.S. National Library of Medicine (DailyMed), 6 Oct 2026. dailymed.nlm.nih.gov
  2. 2Randomized dose-escalation trial of elamipretide in adults with primary mitochondrial myopathy Neurology, 3 Apr 2018. pubmed.ncbi.nlm.nih.gov
  3. 3Phase 2a Clinical Trial of Mitochondrial Protection (Elamipretide) During Stent Revascularization in Patients With Atherosclerotic Renal Artery Stenosis Circulation: Cardiovascular Interventions, Sep 2017. pubmed.ncbi.nlm.nih.gov
  4. 4Phase 1 Clinical Trial of Elamipretide in Intermediate Age-Related Macular Degeneration and High-Risk Drusen: ReCLAIM High-Risk Drusen Study Ophthalmology Science, Mar 2022. pubmed.ncbi.nlm.nih.gov
  5. 5Phase 1 Clinical Trial of Elamipretide in Dry Age-Related Macular Degeneration and Noncentral Geographic Atrophy: ReCLAIM NCGA Study Ophthalmology Science, Mar 2022. pubmed.ncbi.nlm.nih.gov
  6. 6Open-Label Extension Trial to Characterize the Long-term Safety and Tolerability of Elamipretide in Subjects With Genetically Confirmed Primary Mitochondrial Myopathy (PMM) (NCT02976038) ClinicalTrials.gov, 17 Dec 2021. clinicaltrials.gov
  7. 7Effects of Intravenous Bendavia™ on Reperfusion Injury in Patients Undergoing Angioplasty of the Renal Artery (NCT01755858) ClinicalTrials.gov, 11 Aug 2020. clinicaltrials.gov
  8. 8A Study Investigating the Safety, Tolerability, and Efficacy of Elamipretide Topical Ophthalmic Solution for the Treatment of Fuchs’ Corneal Endothelial Dystrophy (FCED) (NCT02653391) ClinicalTrials.gov, 17 Sep 2021. clinicaltrials.gov
  9. 9FRDA Investigator Initiated Study (IIS) With Elamipretide (NCT05168774) ClinicalTrials.gov, 12 Dec 2025. clinicaltrials.gov
  10. 10A Study Investigating the Safety, Tolerability, and Efficacy of Elamipretide Topical Ophthalmic Solution for Treatment of Leber’s Hereditary Optic Neuropathy (NCT02693119) ClinicalTrials.gov, 30 Nov 2021. clinicaltrials.gov
  11. 11A Phase 2 Study to Evaluate the Cardiac and Renal Effects of Short Term Treatment With Elamipretide in Patients Hospitalized With Congestion Due to Heart Failure (NCT02914665) ClinicalTrials.gov, 28 Jul 2020. clinicaltrials.gov
  12. 12A Study to Evaluate the Effects of 4 Weeks Treatment With Subcutaneous Elamipretide on Left Ventricular Function in Subjects With Stable Heart Failure With Preserved Ejection Fraction (NCT02814097) ClinicalTrials.gov, 7 Sep 2017. clinicaltrials.gov
  13. 13A Phase 1 Study Examining the Pharmacokinetics and Tolerability of a Single Oral Dose of Bendavia (MTP-131) (NCT01754818) ClinicalTrials.gov, 6 Feb 2013. clinicaltrials.gov
  14. 14Safety and Pharmacokinetic (PK) Study of Oral Bendavia Administered for 7 Days (NCT01786915) ClinicalTrials.gov, 2 Apr 2014. clinicaltrials.gov
  15. 15A Study of MTP-131 Topical Ophthalmic Solution in Subjects With Diabetic Macular Edema and Non-Exudative Intermediate Age-related Macular Degeneration (NCT02314299) ClinicalTrials.gov, 26 Oct 2015. clinicaltrials.gov
  16. 16The Impact of Intravenous Bendavia™ on Endothelial Reactivity Dysfunction in Cigarette Smoking (NCT01518985) ClinicalTrials.gov, 19 Apr 2012. clinicaltrials.gov
  17. 17Elamipretide (CID 11764719) PubChem, NCBI, accessed 7 Oct 2026. pubchem.ncbi.nlm.nih.gov
  18. 18FORZINITY (elamipretide) injection prescribing information Stealth BioTherapeutics via DailyMed (U.S. National Library of Medicine), 10 Dec 2025. dailymed.nlm.nih.gov
  19. 19Serendipity and the discovery of novel compounds that restore mitochondrial plasticity Clinical Pharmacology & Therapeutics, Dec 2014. pmc.ncbi.nlm.nih.gov
  20. 20Approval letter for NDA 215244, Forzinity (elamipretide) injection U.S. Food and Drug Administration, 19 Sep 2025. accessdata.fda.gov
  21. 21NDA 215244 Integrated Review (Forzinity, elamipretide) U.S. Food and Drug Administration, CDER, 19 Sep 2025. accessdata.fda.gov
  22. 22EMBRACE STEMI study: a Phase 2a trial to evaluate the safety, tolerability, and efficacy of intravenous MTP-131 on reperfusion injury in patients undergoing primary percutaneous coronary intervention European Heart Journal, 21 Apr 2016. pubmed.ncbi.nlm.nih.gov
  23. 23Evaluation of Myocardial Effects of MTP-131 for Reducing Reperfusion Injury in Patients With Acute Coronary Events (NCT01572909) ClinicalTrials.gov, 11 Jun 2020. clinicaltrials.gov
  24. 24Efficacy and Safety of Elamipretide in Individuals With Primary Mitochondrial Myopathy: The MMPOWER-3 Randomized Clinical Trial Neurology, 18 Jul 2023. pubmed.ncbi.nlm.nih.gov
  25. 25ReCLAIM-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, Jan 2025. pubmed.ncbi.nlm.nih.gov
  26. 26Study to Evaluate Efficacy and Safety of Elamipretide in Subjects With Primary Mitochondrial Disease From Nuclear DNA Mutations (nPMD) (NCT05162768) ClinicalTrials.gov, 24 Oct 2025. clinicaltrials.gov
  27. 27Effects of Elamipretide on Left Ventricular Function in Patients With Heart Failure With Reduced Ejection Fraction: The PROGRESS-HF Phase 2 Trial Journal of Cardiac Failure, May 2020. pubmed.ncbi.nlm.nih.gov
  28. 28In vivo mitochondrial ATP production is improved in older adult skeletal muscle after a single dose of elamipretide in a randomized trial PLOS ONE, 2021. pmc.ncbi.nlm.nih.gov
  29. 29A Phase 2 Study to Evaluate the Impact of MTP-131 (Bendavia™) on Skeletal Muscle Function in Elderly (NCT02245620) ClinicalTrials.gov, 23 Jun 2020. clinicaltrials.gov
  30. 30Novel Mitochondria-Targeting Peptide in Heart Failure Treatment: A Randomized, Placebo-Controlled Trial of Elamipretide Circulation: Heart Failure, Dec 2017. pubmed.ncbi.nlm.nih.gov
  31. 31A randomized crossover trial of elamipretide in adults with primary mitochondrial myopathy Journal of Cachexia, Sarcopenia and Muscle, Aug 2020. pubmed.ncbi.nlm.nih.gov
  32. 32Elamipretide Topical Ophthalmic Solution for the Treatment of Subjects with Leber Hereditary Optic Neuropathy: A Randomized Trial Ophthalmology, Apr 2024. pubmed.ncbi.nlm.nih.gov
  33. 33A 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, Mar 2021. pubmed.ncbi.nlm.nih.gov
  34. 34Long-term efficacy and safety of elamipretide in patients with Barth syndrome: 168-week open-label extension results of TAZPOWER Genetics in Medicine, Jul 2024. pubmed.ncbi.nlm.nih.gov
  35. 35Mighty Therapeutics Announces First Patient Dosed in Phase 4 Confirmatory Study of Elamipretide in Barth Syndrome Mighty Therapeutics, 8 Jul 2026. mightytx.com
  36. 36SS-31 (10 mg Vial) Dosage Protocol PeptideDosages.com, 4 Oct 2026. peptidedosages.com
  37. 37Study of Healthy Aging and Physical Function With Elamipretide (NCT07275424) ClinicalTrials.gov, 10 Dec 2025. clinicaltrials.gov
  38. 38Mitochondrial-targeted peptide rapidly improves mitochondrial energetics and skeletal muscle performance in aged mice Aging Cell, Oct 2013. pubmed.ncbi.nlm.nih.gov
  39. 39Late-life restoration of mitochondrial function reverses cardiac dysfunction in old mice eLife, 10 Jul 2020. pmc.ncbi.nlm.nih.gov
  40. 40The Mitochondria-Targeted Peptide Therapeutic Elamipretide Improves Cardiac and Skeletal Muscle Function During Aging Without Detectable Changes in Tissue Epigenetic or Transcriptomic Age Aging Cell, Jun 2025. pmc.ncbi.nlm.nih.gov
  41. 41Clinical Trial in Patients With Barth Syndrome- 4TAZPower (NCT07531251) ClinicalTrials.gov, 17 Sep 2026. clinicaltrials.gov
  42. 42ReNEW:Phase 3 Study of Efficacy, Safety & Pharmacokinetics of Subcutaneous Injections of Elamipretide in Subjects With Dry Age-Related Macular Degeneration (Dry AMD) (NCT06373731) ClinicalTrials.gov, 17 Sep 2026. clinicaltrials.gov
  43. 43Ascension Peptides shop page sorted by popularity Ascension Peptides (vendor), accessed 7 Oct 2026. ascensionpeptides.com (seller page, deliberately not linked)
  44. 44Warning letter to Peak Performance Peptides (MARCS-CMS 735127) U.S. Food and Drug Administration, 24 Aug 2026. fda.gov
  45. 45Warning letter to Royal Peptides LLC (MARCS-CMS 734884) U.S. Food and Drug Administration, 24 Aug 2026. fda.gov
  46. 46Warning letter to Peptide Partners LLC (MARCS-CMS 735063) U.S. Food and Drug Administration, 24 Aug 2026. fda.gov
  47. 47Warning letter to TXP Innovations LLC dba Tex Peptides (MARCS-CMS 735067) U.S. Food and Drug Administration, 24 Aug 2026. fda.gov
  48. 48SS-31: safety testing results and vendor ratings Finnrick, 17 Sep 2026. finnrick.com
  49. 49Think twice before injecting peptides bought online: unauthorized products can seriously harm you (RA-81874) Health Canada, 9 Apr 2026. recalls-rappels.canada.ca
  50. 50What’s in a Name? The Root of Elamipretide Stealth BioTherapeutics (Mighty Therapeutics website), 5 May 2016. mightytx.com

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