HomePeptidesSS-31 (elamipretide)
SS-31 (elamipretide): what it is, what the studies show and where it stands
SS-31, generic name elamipretide, is a four-amino-acid peptide that binds cardiolipin in the inner mitochondrial membrane. It is approved in the US as Forzinity, a once-daily injection under the skin for Barth syndrome.
At a glance
US Approved for one use
Canada Not authorized
Group Longevity
Sources 16
Checked 10 Oct 2026What is SS-31 (elamipretide)?
SS-31, generic name elamipretide, is a four-amino-acid peptide that binds cardiolipin in the inner mitochondrial membrane. It is approved in the US as Forzinity, a once-daily injection under the skin for Barth syndrome. [12]
Other names: elamipretide, Forzinity, MTP-131, Bendavia, D-Arg-2,6-dimethyl-Tyr-Lys-Phe-NH2.
How it has been given to people: subcutaneous injection once daily (approved product); intravenous infusion in some earlier trials.
Looking for doses? SS-31 (elamipretide) dosage chart and vial math
Is SS-31 (elamipretide) approved in the US and Canada?
United States: FDA approved as Forzinity on 19 Sep 2025, under accelerated approval, to improve muscle strength in adults and children with Barth syndrome weighing at least 30 kg. [1]
Canada: No elamipretide or Forzinity product in the Health Canada Drug Product Database. Health Canada names SS-31 among unauthorized injectable peptide drugs it has seized. [14]
Both were checked on 10 Oct 2026 against the regulators' own product databases.
Which approved products contain SS-31 (elamipretide)?
| Product | Country | Approved for | Label |
|---|---|---|---|
| Forzinity | US | To improve muscle strength in adult and pediatric patients with Barth syndrome weighing at least 30 kg. Accelerated approval based on knee extensor muscle strength; continued approval may depend on a confirmatory trial. | Label |
What human studies of SS-31 (elamipretide) exist?
The 11 findings listed here: 9 from randomized human trials and 2 from smaller or observational human studies.
Barth syndrome, randomized part of TAZPOWER (12 patients): 12 weeks of 40 mg a day did not beat placebo on either primary endpoint, walking distance or fatigue score. [3]
The US label says the same of the randomized trial. [1]
Primary mitochondrial myopathy, Phase 3 MMPOWER-3 (218 people, 24 weeks): the trial did not meet its primary endpoints. [7]
In the earlier 36-person intravenous dose-escalation trial, the highest dose group walked 64.5 m farther after 5 days against 20.4 m on placebo (p = 0.053). [5]
MMPOWER-2 (30 people, 4 weeks): the 6-minute walk difference of 19.8 m was not statistically significant. [6]
Healthy older adults (39 people aged 60 to 85 with poorly functioning muscle mitochondria): a single 2-hour infusion raised the muscle's capacity to make ATP right after the infusion, with no difference at day 7 and no effect on fatigue resistance. The abstract gives no dose. [13]
Heart failure, PROGRESS-HF (71 patients, 28 days): no improvement in left ventricular end systolic volume against placebo. [8]
Heart attack, EMBRACE STEMI: a 1-hour infusion did not reduce infarct size. [9]
Dry age-related macular degeneration, ReCLAIM-2 (176 patients, 48 weeks): the primary endpoints were not met. [10]
Knee extensor strength, the basis of the accelerated approval, did not rise in the randomized trial but rose during the open-label extension, which had no placebo group. [1]
In the open-label extension, 6-minute walk distance was better than at the start of the extension at every time point, by 96.1 m at week 168 in the 8 patients who got that far. [4]
What are the side effects of SS-31 (elamipretide)?
Reported in human studies or on a label:
- Injection site reactions are the most common adverse reactions on the label. [1]
- In the Barth syndrome crossover trial the reactions seen more often than on placebo were redness, pain, hardening, itching, bruising and hives at the injection site. [1]
- Eosinophil counts often rose in studies lasting 30 days or more. [1]
- In MMPOWER-2, 80% of participants had injection site reactions on elamipretide, most of them mild. [6]
- In ReCLAIM-2, adverse events were reported by 86% on elamipretide and 71% on placebo. [10]
Warnings on the label
- Contraindicated in people with serious hypersensitivity to elamipretide or any ingredient of Forzinity. [1]
- Hypersensitivity reactions, some needing emergency treatment, have been reported. They may occur within minutes to months of starting. [1]
- Contains benzyl alcohol as a preservative (20 mg per mL). Not approved for use in neonates because of the risk of benzyl alcohol toxicity. [1]
- Not approved for intravenous use. [1]
- Dose is reduced in adults with severe renal impairment. The label gives no dose for adults on dialysis or for children with renal impairment. [1]
- Safety and effectiveness are not established in children under 30 kg. [1]
- Missed dose: skip it and take the next dose at the usual time. Do not take a double dose. [1]
- Overdose is expected to cause histamine-type effects such as low blood pressure or near-fainting. [1]
How does SS-31 (elamipretide) compare with others in its group?
These are the peptides filed under longevity. The last column says whether a randomized human trial is on record for each.
| Peptide | US | Canada | Half-life | Randomized human trial |
|---|---|---|---|---|
| MOTS-c | Not approved | Not authorized | Not found | No |
| Epitalon | Not approved | Not authorized | Not found | No |
| NAD+ | Not approved | Not authorized | Not found | Yes |
| SS-31 (elamipretide) | Approved for one use | Not authorized | Not found | Yes |
| Cardiogen | Not approved | Not authorized | Not found | No |
| Livagen | Not approved | Not authorized | Not found | No |
What could not be found
These were searched for and did not turn up. They are listed so a missing number is not mistaken for a hidden one.
- Human half-life: the US label does not state one, and none was found in the trial abstracts, so half_life is left out. The label does say peak levels come 0.5 to 1 hour after a subcutaneous dose, bioavailability is about 92%, and about 100% of a dose is recovered in urine by 48 hours.
- The label has no drug interactions section. Its pharmacology section reports interaction studies with aspirin, clopidogrel and heparin that found no significant effect.
- No Canadian product monograph: nothing is listed in the Health Canada Drug Product Database.
- No trial with an anti-aging, general wellness or athletic outcome was found. The one study in healthy older adults measured muscle energy output after a single infusion and gives no dose in its abstract [13].
- Elamipretide and SS-31 are not named on the WADA Prohibited List (page checked 2026-10-10, [16]).
SS-31 (elamipretide) questions
Is SS-31 (elamipretide) approved in the US?
FDA approved as Forzinity on 19 Sep 2025, under accelerated approval, to improve muscle strength in adults and children with Barth syndrome weighing at least 30 kg.
Is SS-31 (elamipretide) authorized in Canada?
No elamipretide or Forzinity product in the Health Canada Drug Product Database. Health Canada names SS-31 among unauthorized injectable peptide drugs it has seized.
Has SS-31 (elamipretide) been tested in a randomized human trial?
Yes. At least one randomized human trial is listed on this page.
Sources
Each one was opened on 10 Oct 2026 and matched to the line it supports.
- Stealth Biotherapeutics Inc. FORZINITY (ELAMIPRETIDE HYDROCHLORIDE) INJECTION [STEALTH BIOTHERAPEUTICS INC.] 2025. dailymed.nlm.nih.gov.
- US Food and Drug Administration Drugs@FDA record for NDA215244, FORZINITY (openFDA) 2025. api.fda.gov.
- Reid Thompson W et al. A 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. Genet Med 2021. PubMed 33077895.
- Thompson WR et al. Long-term efficacy and safety of elamipretide in patients with Barth syndrome: 168-week open-label extension results of TAZPOWER. Genet Med 2024. PubMed 38602181.
- Karaa A et al. Randomized dose-escalation trial of elamipretide in adults with primary mitochondrial myopathy. Neurology 2018. PubMed 29500292.
- Karaa A et al. A randomized crossover trial of elamipretide in adults with primary mitochondrial myopathy. J Cachexia Sarcopenia Muscle 2020. PubMed 32096613.
- Karaa A et al. Efficacy and Safety of Elamipretide in Individuals With Primary Mitochondrial Myopathy: The MMPOWER-3 Randomized Clinical Trial. Neurology 2023. PubMed 37268435. Trial NCT03323749.
- Butler J et al. Effects of Elamipretide on Left Ventricular Function in Patients With Heart Failure With Reduced Ejection Fraction: The PROGRESS-HF Phase 2 Trial. J Card Fail 2020. PubMed 32068002.
- Gibson CM et al. EMBRACE 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. Eur Heart J 2016. PubMed 26586786.
- Ehlers JP et al. ReCLAIM-2: A Randomized Phase II Clinical Trial Evaluating Elamipretide in Age-related Macular Degeneration, Geographic Atrophy Growth, Visual Function, and Ellipsoid Zone Preservation. Ophthalmol Sci 2025. PubMed 39605874. Trial NCT03891875.
- Zhao C et al. Elamipretide: The first cardiolipin-directed mitochondrial therapeutic for Barth syndrome approved under accelerated approval. Drug Discov Ther 2026. PubMed 41260682.
- Tung C et al. Elamipretide: A Review of Its Structure, Mechanism of Action, and Therapeutic Potential. Int J Mol Sci 2025. PubMed 39940712.
- Roshanravan B et al. In vivo mitochondrial ATP production is improved in older adult skeletal muscle after a single dose of elamipretide in a randomized trial. PLoS One 2021. PubMed 34264994.
- Health Canada Think twice before injecting peptides bought online: unauthorized products can seriously harm you 2026. recalls-rappels.canada.ca.
- Health Canada Health Canada Drug Product Database, active ingredient search: elamipretide 2026. health-products.canada.ca.
- World Anti-Doping Agency The Prohibited List 2026. wada-ama.org.
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