Description
PrymaLab · Research use only
Preloaded Autoinjector | SS-31 (Elamipretide) | 3ml Pen | 10mg
Elamipretide, a cardiolipin-binding tetrapeptide, in a 3 mL pen listed at 10 mg
SS-31, also known as elamipretide, MTP-131 and Bendavia, is a synthetic four-residue peptide, D-Arg-Dmt-Lys-Phe-NH2, that gathers at the inner mitochondrial membrane and binds the phospholipid cardiolipin. This listing is a preloaded autoinjector pen described as 10 mg of SS-31 in 3 mL of solution, so there is no powder to dissolve. Published work on the peptide covers how it acts on mitochondrial membranes, studies in isolated mitochondria and animal models, and clinical trials in mitochondrial disease and heart attack.
Specifications
| Property | Value |
|---|---|
| Compound | Elamipretide (SS-31, MTP-131); D-Arg-Dmt-Lys-Phe-NH2 |
| CAS number | 736992-21-5 |
| Molecular formula | C32H49N9O5 |
| Contents | SS-31: 10 mg per 3 mL pen (0.33% w/v) |
| Form | Sterile aqueous solution in bacteriostatic water (0.9% benzyl alcohol), supplied in a 3 mL glass cartridge inside a preloaded autoinjector pen fitted with a needle |
| Storage, sealed | Store at 2–8 °C in the original carton, protected from light |
| Safety data sheet | PL-SDS-156 |
What SS-31 is, chemically
SS-31 is a tetrapeptide with an unusual build. Position 1 is D-arginine, the mirror-image form of the amino acid, placed at the N-terminus where aminopeptidases normally start cutting. Position 2 is Dmt, 2,6-dimethyl-L-tyrosine, a non-standard residue. Lysine and phenylalanine follow, and the C-terminus is an amide rather than a free acid, which blocks carboxypeptidases. Capped at both ends, the peptide resists the enzymes that trim short chains from either side.
The two basic residues give it a positive charge at physiological pH, and that charge is what draws it to cardiolipin, the negatively charged lipid of the inner mitochondrial membrane. SS-31 is often grouped with MOTS-c and humanin as a mitochondrial peptide, but the resemblance ends at the organelle: MOTS-c is encoded in mitochondrial DNA, whereas SS-31 is a synthetic design built around a D-amino acid.
Elamipretide the drug and this research pen
Elamipretide received accelerated approval from the FDA in September 2025 under the brand name FORZINITY, for Barth syndrome only and only in the United States, with the approval tied to a confirmatory trial. That approval covers the sponsor’s own drug product. This pen is not FORZINITY, is not made by the drug’s sponsor and carries no approval of any kind; it is sold as research material for laboratory work.
A pen supplies the peptide already in solution at a fixed amount, which removes the reconstitution step but also fixes the concentration. The trade-offs between preloaded pens and freeze-dried vials, including what the diluent adds, are set out in the peptide pen vs vial comparison.
What the research covers
SS-31 belongs to the Szeto-Schiller peptides, a family designed to reach the inner mitochondrial membrane1. There it binds cardiolipin, the phospholipid that shapes the cristae and holds the respiratory complexes together, through both electrostatic and hydrophobic contacts1. Szeto’s 2014 review set out the proposed consequence: with SS-31 bound, cardiolipin no longer converts cytochrome c into a peroxidase, cytochrome c keeps carrying electrons, the cristae stay intact and oxidative phosphorylation is protected1. Supplier pages often call SS-31 an antioxidant, while the label of the approved drug calls it a cardiolipin binder; the guide explains why the second description fits the data better.
Results in people have been mixed. EMBRACE STEMI, a randomized phase 2a trial in patients having primary angioplasty for a first anterior heart attack, found that the peptide (tested as MTP-131) did not reduce infarct size and did not improve any pre-specified imaging, angiographic, electrocardiographic or clinical outcome, although it was well tolerated2. In Barth syndrome, a genetic disorder of cardiolipin, a placebo-controlled crossover trial in 12 subjects missed both of its primary endpoints, the 6-minute walk test and a symptom scale3. In the open-label extension that followed, the eight subjects who reached 36 weeks showed significant gains on both measures3. An open-label phase has no placebo group, so those gains are weaker evidence than the randomized part that preceded them.
None of these studies used a research pen, and none of the abstracts reports how stable the peptide is in solution. The SS-31 (elamipretide) guide covers the full clinical record, including the mitochondrial myopathy trials and the regulatory history of the 2025 approval, along with the competing models of how SS-31 works.
How each lot is tested
Every lot is tested in PrymaLab’s own laboratory in Ashland, Kentucky before release: RP-HPLC for purity, LC-MS for identity, Karl Fischer titration for water, LAL for endotoxin and USP <71> for sterility. Published certificates are listed on the results page and can be checked by number and key on the verify page. The certificate covers the peptide lot used to fill the pen, not the finished solution. These are in-house results from PrymaLab Analytical, not an independent test, and the lab is not accredited to ISO 17025. The third-party testing guarantee on this page still applies: if any independent laboratory finds the wrong compound, or less than the stated purity or amount, the order is refunded and the cost of the test is reimbursed.
Frequently asked questions
Is SS-31 the same compound as elamipretide?
Yes. SS-31, elamipretide, MTP-131 and Bendavia are names for one molecule, the tetrapeptide D-Arg-Dmt-Lys-Phe-NH2. FORZINITY is the brand name of the approved drug made by its sponsor. This pen contains the same peptide sold as research material, and it is not FORZINITY.
How does a preloaded pen differ from freeze-dried peptide in a vial?
A vial of dry powder stays dry until the lab dissolves it, and the lab chooses the volume and so the concentration. The pen arrives with the peptide already in solution, listed at 10 mg in 3 mL, so nothing needs reconstituting but the concentration is fixed. The label on the pen states the amount.
Is SS-31 approved by the FDA?
Elamipretide received accelerated FDA approval in September 2025 as FORZINITY, for Barth syndrome only, in the United States. That approval belongs to the sponsor's drug product. This pen is sold for laboratory research only and is not approved for any use in people or animals.
What does the research show, and what does it leave open?
Laboratory and animal studies describe SS-31 binding cardiolipin and protecting mitochondrial cristae. In people, randomized trials in heart attack and mitochondrial disease missed their primary endpoints, and the gains in Barth syndrome came in an open-label extension. Which molecular target matters most is still argued over.
How do I check the certificate for the pen I received?
Read the lot number on the pen label, find that lot on the testing results page, and confirm the certificate by its number and key on the verify page. The certificate covers the peptide lot used to fill the pen rather than the finished solution.
References
- Szeto HH. First-in-class cardiolipin-protective compound as a therapeutic agent to restore mitochondrial bioenergetics. Br J Pharmacol. 2014;171(8):2029-50. DOI · PubMed
- Gibson CM, Giugliano RP, Kloner RA, 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;37(16):1296-303. DOI · PubMed
- Reid Thompson W, Hornby B, Manuel R, 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;23(3):471-478. DOI · PubMed
Research use only
For laboratory research use only. This product is not a drug, food, cosmetic or dietary supplement, is not approved by the FDA or any comparable authority for human or veterinary use, and must not be given to people or animals. It is sold to qualified researchers and institutions, and the buyer is responsible for lawful handling and disposal.
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