SS-31 (elamipretide) — identity, handling and published literature

An aromatic-cationic tetrapeptide (elamipretide) with binding affinity for cardiolipin in the inner mitochondrial membrane, supplied as 10 mg lyophilised powder for laboratory research use only.

Presentation and physical properties

• Fill mass: 10 mg, in a sealed vial. Supplied without diluent.
• State: lyophilised solid.
• Bulking agent: none recorded in the catalogue entry for this vial. Where mannitol or a comparable bulking agent is present in a lyophilised peptide, it contributes to the gross fill mass and to the appearance of the cake, and it is not peptide.
• Solubility: water-soluble. Dissolves in water and in bacteriostatic water. As a strongly basic peptide with no cysteine, it does not require the reducing or alkaline conditions some peptides do.
• Hygroscopicity: hygroscopic in salt form. An opened vial exposed to humid air will take up water, which affects both mass and stability.
• Acceptable cake: an intact or slightly shrunken white cake, uniform in colour, without melt-back, discoloration or visible moisture. A partially collapsed cake is a lyophilisation defect and is not by itself evidence of chemical degradation, but it should be recorded against the lot.

Reconstitution arithmetic for this vial

Concentration is the vial mass divided by the volume of diluent added:

concentration (mg/mL) = vial mass (mg) ÷ diluent volume (mL)

For this vial the mass is 10 mg, so the arithmetic at the common diluent volumes is as follows. A U-100 graduation is one hundredth of a millilitre, so 1 mL corresponds to 100 units and 0.01 mL to one unit; the final column restates the same concentration per graduation and is a unit conversion, not a recommendation.

These figures describe the solution. They say nothing about how much of it should be used for any purpose, and no such figure is published here or calculated anywhere on this site. The same arithmetic, with the syringe graduation shown, is available in the reconstitution calculator with this vial preselected.

Storage and stability

• Sealed lyophilised solid: −20 °C or below, sealed, desiccated and protected from light.
• Before opening: equilibrate the sealed vial to room temperature. Opening a cold vial draws humid air onto a hygroscopic solid and condenses water into the cake.
• In solution: 2–8 °C, not frozen. Solutions are less stable than the lyophilised solid.
• Freeze–thaw: cycling is avoided. Where a solution must be held beyond short-term refrigeration, single-use aliquots avoid repeated cycles.
• Light: the dimethyltyrosine residue is a phenolic system and, as with tyrosine generally, is susceptible to oxidation and to light-mediated degradation. Amber glass or foil overwrap is the usual control.
• Transit: short periods at 2–8 °C or at ambient temperature during transit do not affect lyophilised material.
• The 28-day figure: the 28 days widely quoted for a reconstituted vial is a convention drawn from the preservative system of bacteriostatic water — the benzyl alcohol content limits the period over which a stoppered container is conventionally regarded as suitable for repeated withdrawal. It is a property of the diluent, not a measured stability figure for this peptide, and it should not be read as one. Sterile water contains no preservative and carries no such convention at all.

Analytical identity and certificate literacy

Characterisation of this compound in the literature and by suppliers is by reversed-phase HPLC and electrospray ionisation mass spectrometry.

Expected masses

Because the molecule is strongly basic, electrospray commonly returns the doubly and triply charged species rather than a dominant singly charged ion, and a spectrum showing them is consistent with the expected charge state rather than evidence of a problem.

What a purity figure does and does not measure

Area-percent purity by HPLC is the proportion of ultraviolet-absorbing material eluting as the main peak, at a stated wavelength, under a stated gradient. It does not measure how much peptide is in the vial, it does not detect counter-ions, residual solvent, salt or water that do not absorb at the wavelength used, and it does not on its own confirm identity — that is what the mass spectrum is for. Two certificates quoting the same percentage under different methods are not stating the same thing.

Net peptide content is the separate figure: the proportion of the gross fill that is peptide rather than counter-ion, residual water and salts, determined by amino acid analysis or nitrogen determination. A 10 mg fill by gross mass is not 10 mg of peptide unless net peptide content is stated and is 100 per cent, which for a strongly basic peptide supplied as a salt it will not be.

Traceability

A certificate is evidence only for the lot it names. Traceability means a certificate carrying a lot identifier, and a route by which that identifier can be matched to the container in hand — through the container itself where it carries one, and otherwise through the supply record. A certificate presented without a lot identifier is a document about some other material.

What the published literature investigated

Studies are grouped by the model in which the work was done. Each line reports what the cited authors investigated and what they reported. No conclusion is drawn across studies.

In vitro and ex vivo

Zhao and colleagues (2004) investigated the subcellular localisation and antioxidant behaviour of the aromatic-cationic Szeto-Schiller peptides in isolated mitochondria, cell culture and isolated perfused organ reperfusion protocols, and reported that the peptides concentrated in the inner mitochondrial membrane, inhibited mitochondrial swelling and oxidative cell death, and reduced injury in their reperfusion protocols. This is the foundational characterisation paper for the series. [1]

Rodent models

Vahle and colleagues (2026) investigated whether targeting mitochondrial dysfunction with elamipretide affected skeletal muscle performance in a rat model of heart failure with preserved ejection fraction, and reported improvement in the skeletal muscle performance measures used in that model. [5]

Song and colleagues (2026) investigated effects on mitochondrial bioenergetics and neural remodelling in a rodent spinal cord injury model, and reported preservation of mitochondrial bioenergetics and effects on the neural remodelling measures used in that model. [6]

Human studies

Reid Thompson and colleagues (2021) investigated elamipretide in a randomised, double-blind, placebo-controlled crossover trial followed by an open-label extension, in participants with Barth syndrome, a genetic disorder of mitochondrial cardiolipin metabolism. The authors reported that neither primary endpoint was met in the randomised, placebo-controlled first part — the six-minute walk test and the Barth Syndrome Symptom Assessment. In the uncontrolled open-label second part they reported improvement on both measures at 36 weeks (six-minute walk +95.9 m, p=0.024; symptom assessment −2.1 points, p=0.031). The two phases are reported here together because that is how the authors reported them. [2]

Karaa and colleagues (2023) investigated elamipretide in a randomised, double-blind, placebo-controlled trial in adults with primary mitochondrial myopathy (MMPOWER-3, n=218), and reported that both co-primary endpoints were not met, with a six-minute walk difference of −3.2 m (p=0.69). This is the largest randomised trial of the compound published to date. [3]

Thompson and colleagues (2024) investigated outcomes and safety over 168 weeks of the open-label extension of the same Barth syndrome trial, in an uncontrolled design, and reported the extension outcomes and safety data over that period. [4]

Reviews and regulatory records

Shirley (2026), in a regulatory approval review, records that in September 2025 the FDA granted accelerated approval to elamipretide under the brand name Forzinity, and describes it as the first disease-specific approval for Barth syndrome. [7]

Villatore and colleagues (2026) review the described mechanism, the trial history and the approval of the compound. [8]

Evidence gaps and limitations

This section exists because it is the part of the record most often left out, and on this compound it is substantial.

• The approval rests on a small, partly negative dataset. The approved use was supported by a trial of twelve participants in which the randomised phase did not meet either primary endpoint, followed by an uncontrolled open-label extension assessed against a surrogate endpoint.
• Accelerated approval is a different evidentiary standard. It is granted on the basis of an endpoint considered reasonably likely to predict clinical benefit, rather than on the demonstration of that benefit itself, and it carries a confirmatory obligation.
• The regulatory decision was contested. The FDA advisory committee split 10 to 6, and the agency issued a Complete Response Letter before its later decision.
• The largest randomised trial was negative. MMPOWER-3 (n=218) did not meet either co-primary endpoint, and the six-minute walk difference was numerically below placebo.
• An uncontrolled extension cannot separate an effect from natural history or expectation. That limitation applies to both open-label phases cited above and is acknowledged in the trial literature itself.
• Concentration of the literature. The foundational characterisation of the series originates with a small number of groups, and the late-stage trial programme was conducted under a single commercial development programme. Independent replication of the late-stage findings has not been identified in the sources used for this entry.
• No published evidence outside the studied populations. No published study identified for this entry examined the compound in healthy adults, in ageing, in muscle mass maintenance or in athletic performance — despite the designation SS-31 being marketed in contexts that imply those uses. That absence is a fact about the literature and it is stated here deliberately.
• Non-rodent animal data. No non-rodent animal studies were identified in the sources used for this entry.
• Toxicology of research-grade material. The manufacturing, controls and toxicology package behind an approved medicinal product do not transfer to material supplied for laboratory research use. Nothing about the approval says anything about the material described on this page.
• No study has evaluated this material. No published study has assessed material supplied by NovoVita. The literature above concerns the molecule, not the product.

Regulatory and standards position

United Kingdom

There is no UK marketing authorisation for elamipretide, and none in the EU. The EMA granted orphan designation, which is a development status conferred on a candidate for a rare condition and is not an authorisation to market. Material supplied for laboratory research use is not a medicinal product and is not authorised by the MHRA or by any other regulator for human or veterinary use.

United States

The same molecule is the active ingredient in Forzinity, a medicinal product granted accelerated approval by the FDA on 19 September 2025 for one rare inherited mitochondrial condition. NovoVita’s material is not that medicine, is not manufactured to medicinal standard, and is not supplied for human or veterinary use.

This is worth stating plainly because it is unusual in this catalogue: for most compounds listed here, no approved medicinal product exists anywhere. For this one it does, in another jurisdiction. That changes nothing about what is supplied here or how it may lawfully be described, and it is recorded as a fact about the molecule rather than as a recommendation about the material.

Other classifications

• FDA bulk drug substance category: not established from the sources used for this entry.
• WADA: not established from the sources used for this entry. The current Prohibited List is the authoritative record and is revised annually.
• Export restriction: none. The restriction held in this catalogue applies to somatropin only.

Laboratory handling and safety

• GHS classification: no harmonised classification was identified in the sources used for this entry. In the absence of one, handle the material as a substance of unknown toxicity.
• Personal protective equipment: nitrile gloves, safety spectacles and a laboratory coat as a minimum.
• Dust: lyophilised solids aerosolise readily. Open vials and transfer solid in a ventilated enclosure, and avoid any operation that generates airborne powder.
• Condensation: allow the sealed vial to reach room temperature before breaking the seal. The material is hygroscopic and a cold vial will condense water into the cake.
• Spills: do not sweep dry. Dampen, collect into a sealed container and decontaminate the surface. Treat the collected material as chemical waste.
• Disposal: dispose of surplus material, solutions and contaminated consumables as chemical waste under local regulations. Do not discharge to drain.
• Records: record lot identifier, date of reconstitution, diluent used and storage conditions at the point of reconstitution. A solution without that record cannot be interpreted later.

Related compounds and consumables

• Same category — NAD+ and MOTS-C in Longevity & Cellular.
• Diluents — bacteriostatic water and sterile water. The difference between them is the preservative, and it is the reason the 28-day convention above applies to one and not the other.
• Arithmetic — reconstitution calculator, with this vial preselected.

Availability

SS-31 10 mg · SKU 2S10 · £29.99

Stock state and ordering are resolved from the catalogue at render time. Where this SKU is not currently published, this block reads Not currently listed and no link is shown.

References

1. Zhao K, Zhao GM, Wu D, Soong Y, Birk AV, Schiller PW, Szeto HH. Cell-permeable peptide antioxidants targeted to inner mitochondrial membrane inhibit mitochondrial swelling, oxidative cell death, and reperfusion injury. J Biol Chem. 2004;279(33):34682–90. Model: in vitro and ex vivo — isolated mitochondria, cell culture, isolated perfused organ reperfusion. PMID 15178689 · doi:10.1074/jbc.M402999200
2. Reid Thompson W, Hornby B, Manuel R, Bradley E, Laux J, Carr J, Vernon HJ. Genet Med. 2021;23(3):471–8. Model: human — randomised, double-blind, placebo-controlled crossover trial, followed by an uncontrolled open-label extension. PMID 33077895
3. Karaa A, et al. MMPOWER-3. Neurology. 2023. Model: human — randomised, double-blind, placebo-controlled trial in adults with primary mitochondrial myopathy, n=218. PMID 37268435
4. Thompson WR, Manuel R, Abbruscato A, Carr J, Campbell J, Hornby B, Vaz FM, Vernon HJ. Genet Med. 2024;26(7):101138. Model: human — 168-week uncontrolled open-label extension of the TAZPOWER trial. PMID 38602181
5. Vahle B, et al. Targeting mitochondrial dysfunction with elamipretide (SS-31) improves skeletal muscle performance in a HFpEF rat model. Circ Heart Fail. 2026. Model: rodent — rat model of heart failure with preserved ejection fraction. PMID 42290373
6. Song Z, et al. Neurochem Int. 2026. Model: rodent — spinal cord injury model. PMID 42082001
7. Shirley M. Elamipretide: first approval. Drugs. 2026;86(3):377–83. Model: regulatory approval review. PMID 41335372
8. Villatore A, et al. Trends Pharmacol Sci. 2026. Model: journal article (PubMed carries no abstract; type not stated). PMID 42448476
9. Identity data — PubChem CID 11764719. PubChem record
10. FDA prescribing information for Forzinity (elamipretide), 2025 — cited for regulatory status only. FDA label
11. NIHR Innovation Observatory. Elamipretide for Barth syndrome, December 2024 — cited for the absence of EU and UK marketing authorisation. NIHR briefing

Last reviewed 8 August 2026 — first publication of this entry. Monoisotopic and ESI ion masses calculated from the molecular formula. Regulatory position checked against the FDA approval record and the NIHR briefing on the absence of an EU or UK marketing authorisation.

Research use only

Supplied strictly for laboratory research use. This product is not a medicine, is not authorised by the MHRA or any other regulator for human or veterinary use, and is not supplied for consumption, ingestion, injection or administration to humans or animals. No claim is made or implied that it diagnoses, treats, cures or prevents any disease or condition. Purchasers are responsible for ensuring they are legally permitted to obtain and handle this material.