Elamipretide
A four-amino-acid peptide that homes to the powerhouse of the cell and steadies its membranes; the first drug approved to target that machinery in Barth syndrome
Mitochondria, the structures that turn food and oxygen into the cell's energy, depend on a fatty molecule called cardiolipin to keep their inner membrane folded and working. In several diseases that membrane is damaged and energy production fails. Elamipretide, long studied as SS-31, is a small, positively charged four-amino-acid peptide that slips into cells, concentrates in the inner mitochondrial membrane and binds cardiolipin, helping the membrane hold its shape, make ATP and generate fewer damaging free radicals. After a long development programme across several conditions, it was approved in the United States in 2025, as Forzinity, to improve muscle strength in Barth syndrome, a rare inherited disorder of cardiolipin. It is a prescription medicine given by injection under the skin.
Manufacturer's recommended dosing (FDA label): 40 mg, Once daily, Subcutaneous Details ↓
Recommended Dosing
Manufacturer's recommended dosing (FDA label)
From the prescribing information. Other doses studied, if any, are in the full dosing data below.
Work out syringe units → · New to syringes? · All dosing data ↓
What is it?
Every cell runs on mitochondria, and mitochondria run on a well-folded inner membrane studded with the chain of proteins that makes ATP. Holding that membrane in its tight, folded shape is a signature fatty molecule, cardiolipin. When cardiolipin is wrong or damaged, the membrane loosens, energy output drops and the leaky chain spills reactive oxygen species that do further harm. A family of rare and common diseases, from inherited mitochondrial disorders to heart failure, share that failure.
Elamipretide was designed to act exactly there. It is a tetrapeptide, just four amino acids, built with a pattern of positive charge and aromatic rings that lets it cross cell membranes without a transporter and gather in the inner mitochondrial membrane. There it binds cardiolipin and, as its developers describe it, helps the membrane keep its shape, restores more orderly energy production and curbs the overproduction of reactive oxygen species. Because it works on the membrane rather than on one enzyme, it was tested broadly, first as SS-31 in the laboratory and then, as MTP-131 and Bendavia, in people.
Its clearest proving ground became Barth syndrome, a rare, X-linked disease in which a faulty gene (TAFAZZIN) cannot finish building cardiolipin. Children and adults with it have a weak, enlarged heart, weak skeletal muscles, poor growth and a cyclic drop in infection-fighting white cells, and the condition can be fatal in infancy. In the TAZPOWER trial and its long open-label extension, daily elamipretide was followed over years; the muscle-strength measure that supported approval was an improvement in knee-extensor strength. On that basis the US regulator granted accelerated approval in 2025, branded Forzinity, to improve muscle strength in Barth syndrome in patients weighing at least 30 kilograms.
The road there was not a straight line. A large, separate programme tested elamipretide in primary mitochondrial myopathy, a broader group of genetic muscle disorders: a phase 2 dose-escalation study (MMPOWER-1), a crossover study of the subcutaneous form (MMPOWER-2) and a pivotal phase 3 trial (MMPOWER-3) of 40 milligrams a day against placebo for 24 weeks. That phase 3 programme did not deliver the result needed for approval in mitochondrial myopathy, and the drug was not approved for it. The accelerated approval rests on the Barth-syndrome muscle-strength finding, an intermediate endpoint, with continued approval tied to confirming clinical benefit.
Elamipretide has also been studied, without approval, in heart failure, in acute kidney and heart injury (as Bendavia), and in the eye disease dry age-related macular degeneration, reflecting the wide reach of mitochondrial dysfunction. Those remain investigational.
As an approved medicine, elamipretide is a prescription drug used under specialist care, given as a daily injection under the skin, with the dose reduced in severe kidney impairment. It is not a general-purpose 'mitochondrial' supplement, and nothing on this page is medical advice; its use belongs with a doctor who manages the underlying disease.
Mechanism of Action
Elamipretide works on the inner membrane of the mitochondrion rather than on a single enzyme. By binding cardiolipin it helps the membrane keep the shape its energy machinery needs.
Cardiolipin on the inner membrane
The peptide's charge-and-aromatic pattern carries it across membranes and concentrates it in the inner mitochondrial membrane, where it binds cardiolipin, the fat that keeps that membrane folded (PMID 34623544, FDA GSRS UNII 87GWG91S09). In Barth syndrome cardiolipin itself is defective, which is why the disease was a natural target.
Better energy production
Stabilising cardiolipin helps the electron-transport chain stay organised, so the mitochondrion makes ATP more efficiently; the drug is described as improving energy production in affected cells (PMID 34623544).
Fewer reactive oxygen species
A leaky, disorganised chain spills reactive oxygen species that damage the cell; by steadying it, elamipretide curbs that excess and the oxidative stress it causes (PMID 34623544).
Muscle strength in Barth syndrome
The clinical signal that supported approval was an improvement in knee-extensor muscle strength in Barth syndrome, an intermediate endpoint, measured in the TAZPOWER programme (FORZINITY US label; PMID 38602181).
Published Research
These are studies of elamipretide read from their PubMed abstracts on November 5, 2026. The clinical record has two arms: the MMPOWER programme in primary mitochondrial myopathy (a phase 2 dose-escalation study, a crossover study and the pivotal phase 3), and the TAZPOWER programme in Barth syndrome whose muscle-strength result supported approval, plus a review of its mitochondrial mechanism. Every title names the drug.
Phase 2 dose-escalation in mitochondrial myopathy
MMPOWER-1 assessed the safety, tolerability and efficacy of elamipretide, described as an aromatic-cationic tetrapeptide that readily enters cells and localises to the inner mitochondrial membrane where it associates with cardiolipin, in adults with primary mitochondrial myopathy. An early dose-escalation study, it set up the subcutaneous dosing and the outcome measures (notably the six-minute walk) carried into the later trials.
Crossover trial of the subcutaneous form
MMPOWER-2 was a randomized, double-blind, placebo-controlled crossover trial of subcutaneous elamipretide in adults with primary mitochondrial myopathy, using the six-minute walk test, patient-reported fatigue, functional measures and safety to guide the design of the phase 3 trial.
Pivotal phase 3 in mitochondrial myopathy (MMPOWER-3)
MMPOWER-3 was the pivotal phase 3 trial: participants with genetically confirmed primary mitochondrial myopathy were randomized one-to-one to 24 weeks of elamipretide 40 mg a day or placebo, given subcutaneously. The trial tested whether the drug improved physical function and quality of life in this broad group; its result did not support approval in mitochondrial myopathy, and the drug was not approved for that use.
Barth syndrome cardiomyopathy
A report on elamipretide in Barth syndrome, the rare X-linked disease of cardiomyopathy, muscle weakness, growth delay and cyclic neutropenia caused by faulty cardiolipin. It describes the rationale and early evidence for a water-soluble, mitochondria-targeting tetrapeptide that improves energy production and limits reactive oxygen species in a disease that is, at root, a cardiolipin defect.
Long-term use in Barth syndrome (TAZPOWER extension)
The long-term, open-label extension of TAZPOWER: after a 28-week randomized, placebo-controlled phase, patients with Barth syndrome continued elamipretide 40 mg subcutaneously daily for up to 168 weeks. The extension tracked the durability of the muscle-strength and functional gains and the long-term safety that supported the accelerated approval.
The mitochondrial mechanism
A review of targeting mitochondrial dysfunction with elamipretide, set against the problem that standard heart-failure therapy slows but does not stop disease progression. It lays out how a cardiolipin-binding peptide could address the energetic failure common to heart failure and the inherited mitochondrial diseases.
Dosing Data
Elamipretide is an approved medicine, and the dose below is the manufacturer's recommended dosing from the US FORZINITY label, not a figure from a trial or a community. It is a prescription injection used under specialist care for Barth syndrome; the dose is reduced in severe kidney impairment.
Educational information, not medical advice. Each dose above is tagged with its source: an approved label, a published human study, animal data, or amounts reported by users. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose. Full medical disclaimer.
What a Buyer Needs to Know
What is sold, how it is mixed, stored and taken, and what is known about its safety, quality and legal status. Each part names its source. Where we have none, it says unknown.
What is sold
The approved product, as its label describes it:
- Forzinity (elamipretide hydrochloride injection): Injection: 280 mg/3.5 mL (80 mg/mL) solution for injection in single-patient-use vials. Forms the label lists: single-patient-use vials.
Source: Forzinity (elamipretide hydrochloride injection) label, section 3 (DailyMed version 10, effective December 10, 2025).
Mixing a vial: a worked example
Nothing to mix: the label gives Forzinity (elamipretide hydrochloride injection) as single-patient-use vials, ready to use.
Source: Forzinity (elamipretide hydrochloride injection) label, sections 2, 3 and 16 (DailyMed version 10, effective December 10, 2025).
Storage before and after mixing
Before mixing or first use: “Store refrigerated at 2°C to 8°C (36°F to 46°F).” “Do not freeze.” “Discard vials 8 days after first opening.”
After mixing or first use: “Following the first dose, the opened vial can be stored either refrigerated 2°C to 8°C (36°F to 46°F) or at room temperature between 20°C to 25°C (68°F to 77°F).”
Source: Forzinity (elamipretide hydrochloride injection) label, sections 16 and 2 (DailyMed version 10, effective December 10, 2025).
How it is taken
As the approved label gives it: Subcutaneous (Once daily; Barth syndrome, patients >=30 kg).
Source: Manufacturer's recommended dosing (FDA label): the route and frequency of each row in Dosing Data below.
What to expect, and when
How long it stays in the body: a half-life of dosed once daily by subcutaneous injection. After about five half-lives almost none is left.
When effects appear: unknown; no source on this page gives a time to effect for Elamipretide. Results reported in the studies are under Published Research.
Source: half-life: FORZINITY US prescribing information (DailyMed set 146bf34c, version 10, effective December 10, 2025).
Side effects, and when to stop or get help
From the Side Effects section: Given by daily subcutaneous injection; injection-site reactions are a typical class effect of such drugs; The dose is reduced in adults with severe renal impairment (eGFR below 30), per the label; The product contains the preservative benzyl alcohol; the label advises against use where this is a concern (follow the product label); As an accelerated approval, continued approval may depend on trials confirming clinical benefit; Full, current safety information is in the FORZINITY prescribing information, which governs its use. Full list and cautions ↓
When to stop or get help: unknown; the label's warnings summary we read gives no rule for stopping Elamipretide. Treat a severe or unexpected reaction as a reason to stop and see a doctor.
Source: the Side Effects section below (“From the trials and the approved US label; the label carries the authoritative safety information for its approved use”).
Interactions
Unknown: a PubMed search for human interaction studies of Elamipretide (reviewed 2026-11-05) found none. Unknown is not the same as safe to combine.
Every peptide's record, with its source: the interaction matrix.
Checking what you bought
Unknown: no published independent test of Elamipretide products is in our lab-results database yet, so how products sold under this name measure up is not known.
To read a certificate of analysis, paste it into the COA decoder. Trust & Verification explains what independent testing can and cannot show.
Legal status
US: FDA Approved. Sport: Not on the 2026 List.
Country by country ↓ · Regulatory tracker
Source: this entry's approval status and the WADA Prohibited List, as in Legal Status below.
Side Effects & Contraindications
Reported Side Effects
From the trials and the approved US label; the label carries the authoritative safety information for its approved use.
Contraindications & Cautions
These points come from the approved label and the drug's approved use. The label is authoritative.
Legal Status
Elamipretide (Forzinity) is an FDA-approved prescription medicine for Barth syndrome; its other studied uses are investigational.
Frequently Asked Questions
?What is elamipretide?
A four-amino-acid peptide, long known as SS-31, that targets the inner membrane of the mitochondrion and binds cardiolipin, the fat that keeps that membrane working. As the brand Forzinity it is approved to improve muscle strength in Barth syndrome.
?Is it approved?
Yes, in the United States. The FDA gave Forzinity accelerated approval in September 2025 for Barth syndrome in patients weighing at least 30 kg, based on an improvement in knee-extensor muscle strength (an intermediate endpoint). It is not approved for other mitochondrial diseases.
?How is it given and dosed?
As a subcutaneous injection, 40 mg once daily for patients weighing 30 kg or more (20 mg once daily in adults with severe kidney impairment), per the US label. It is a prescription medicine used under specialist care.
?How does it work?
It concentrates in the inner mitochondrial membrane and binds cardiolipin, helping the membrane keep its shape so the cell makes energy more efficiently and spills fewer damaging free radicals (PMID 34623544). Barth syndrome is itself a disease of faulty cardiolipin.
?Did it work for mitochondrial myopathy?
Not for approval. A large programme (MMPOWER-1 to -3) tested it in primary mitochondrial myopathy; the pivotal phase 3 (MMPOWER-3) did not deliver the result needed, and it is not approved for that condition (PMID 37268435).
?Can I buy it as a peptide?
No. Elamipretide is a prescription medicine (Forzinity) for a specific rare disease, dispensed under medical supervision. Grey Peptides lists no sellers and recommends no source; material sold as 'SS-31' outside that system is not the approved product.
References
- [clinical-trial] Karaa A, et al. "Randomized dose-escalation trial of elamipretide in adults with primary mitochondrial myopathy." Neurology, 2018;90(14):e1212-e1221. PMID: 29500292.
- [clinical-trial] Karaa A, et al. "A randomized crossover trial of elamipretide in adults with primary mitochondrial myopathy." J Cachexia Sarcopenia Muscle, 2020;11(4):909-918. PMID: 32096613.
- [rct] Karaa A, et al. "Efficacy and Safety of Elamipretide in Individuals With Primary Mitochondrial Myopathy: The MMPOWER-3 Randomized Clinical Trial." Neurology, 2023;101(3):e238-e252. PMID: 37268435.
- [clinical-trial] Sabbah HN. "Elamipretide for Barth syndrome cardiomyopathy: gradual rebuilding of a failed power grid." Heart Fail Rev, 2022;27(5):1911-1923. PMID: 34623544.
- [clinical-trial] 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;26(7):101138. PMID: 38602181.
- [review] Obi C, et al. "Targeting mitochondrial dysfunction with elamipretide." Heart Fail Rev, 2022;27(5):1925-1932. PMID: 35037146.
- [label] FORZINITY (elamipretide hydrochloride) US prescribing information, Stealth BioTherapeutics (DailyMed set 146bf34c, version 10, effective December 10, 2025), read November 5, 2026: indicated to improve muscle strength in adult and pediatric patients with Barth syndrome weighing at least 30 kg, under accelerated approval; recommended dosage 40 mg subcutaneously once daily (20 mg once daily in adults with severe renal impairment).
- [other] FDA Global Substance Registration System, Elamipretide, UNII 87GWG91S09 (INN 10154, CAS 736992-21-5, PubChem 11764719; codes SS-31, MTP-131, Bendavia), read November 5, 2026: an aromatic-cationic tetrapeptide, D-arginyl-2',6'-dimethyl-L-tyrosyl-L-lysyl-L-phenylalaninamide. https://gsrs.ncats.nih.gov/ginas/app/beta/substances/87GWG91S09
- [other] ChEMBL molecule CHEMBL3833370 (ELAMIPRETIDE), read November 5, 2026: synonyms Elamipretide, Elamipretida, SS-31, MTP-131, Bendavia; highest clinical phase recorded 3 (now approved). https://www.ebi.ac.uk/chembl/compound_report_card/CHEMBL3833370/
- [other] US FDA: elamipretide (brand FORZINITY, Stealth BioTherapeutics) received accelerated approval in September 2025 for Barth syndrome; the FDA label (DailyMed) was read November 5, 2026.
Sources & Citations
The six studies carded above were read from their PubMed records on November 5, 2026. Structure and codes come from the FDA Global Substance Registration System (UNII 87GWG91S09) and ChEMBL (CHEMBL3833370); the approved indication and dosing from the FORZINITY US prescribing information (DailyMed version 10, effective December 10, 2025), read the same day. Grey Peptides sells nothing and links to no vendor.
Medical Disclaimer: This content is for educational and informational purposes only. It is not medical advice, and nothing here is an instruction to obtain or use any compound. Talk to a licensed clinician about your own situation.