Where to buy SS-31.

You can buy SS-31 from a research-supply vendor as lab powder, or get it from a specialty pharmacy on prescription if you have Barth syndrome. Those are the two live answers to where to buy SS-31. It became the third FDA-approved peptide in this library when the agency cleared Forzinity in September 2025, which closed most of the compounding route.

SS-31

Referenced in this guide

Batch-matched COAHPLC + mass specResearch use only

The SS-31 referenced throughout this article, supplied as a research compound with a certificate of analysis matched to the lot you receive — the check this site argues you should hold any supplier to.

Shop SS-31

What is SS-31?

SS-31 is a four-amino-acid peptide reading D-Arg-Dmt-Lys-Phe-NH₂. Two features make it strange. It uses a D-amino acid, the mirror image of the normal form, and it carries a non-standard residue most peptide suppliers can't make cleanly.

That residue, Dmt, is 2',6'-dimethyltyrosine. It's tyrosine with two extra methyl groups on the ring, and it isn't sold as an off-the-shelf building block.

The 2025 Tung review describes elamipretide as a cell-permeable peptide that "selectively concentrates in the inner mitochondrial membrane, where it binds cardiolipin." Cardiolipin is the signature lipid of healthy mitochondria.

SS-31 stabilizes cristae structure and props up the cardiolipin–cytochrome c supercomplex. That's the mechanism the whole clinical program rests on.

Stealth BioTherapeutics took it through a real Phase III program. In September 2025 the FDA granted accelerated approval under the brand name Forzinity, for adult and pediatric Barth syndrome patients weighing ≥30 kg.

That made elamipretide the third FDA-approved peptide in this encyclopedia, behind tesamorelin and bremelanotide.

Where can you buy SS-31?

You can buy SS-31 from a research-supply vendor, or receive it as Forzinity from a specialty pharmacy with a Barth syndrome diagnosis. Compounded elamipretide was a third route until September 2025, and the approval largely closed it. Here's what each one gives you.

• A research-supply vendor. $80–$220 per vial, lyophilized, Research Use Only, no prescription. The route open to everyone, and the one the rest of this guide covers.
• A specialty pharmacy, on prescription. Forzinity, at $300,000–$750,000 per patient-year. Requires a confirmed Barth syndrome diagnosis and a body weight of at least 30 kg.
• A 503A compounding pharmacy. Largely closed since the approval, because 503A generally bars compounding essentially a copy of an approved drug.

1. Prescription Forzinity, FDA-approved in September 2025

Forzinity is the FDA-approved version of elamipretide. Stealth makes it under cGMP, the FDA's quality standard for drugs, and a specialty pharmacy dispenses it on prescription to Barth syndrome patients weighing ≥30 kg.

The approval rests on TAZPOWER: 28 weeks of randomized testing plus a 168-week open-label extension, with 8 of 10 patients reaching the extension endpoint. The FDA still requires post-marketing confirmatory trials.

Pricing is orphan-drug territory, roughly $300,000 to $750,000 per patient per year. Insurance pre-authorization and patient-assistance programs run through Stealth and the specialty pharmacy.

2. 503A compounded elamipretide, now sharply limited

503A is the section of federal law letting compounding pharmacies make custom formulations for individual patients. Before September 2025, some 503A pharmacies prepared elamipretide for off-label use. The approval changed that.

Once a drug is FDA-approved as a finished product, 503A generally bars a compounding pharmacy from making essentially a copy of it. So that route is now largely closed to you, outside narrow shortage exceptions in FDA Section 503A.

3. Research-grade SS-31, sold Research Use Only

Chemical suppliers sell SS-31 under Research Use Only labeling for laboratory work. It's nominally the same tetrapeptide as Forzinity. The manufacturing controls, quality assurance and intended use are not the same.

Research SS-31 suits in-vitro and animal work matching the published literature. It isn't equivalent to prescription Forzinity, and selling it for human consumption is illegal. This is the channel we cover for the rest of our guide.

Five vendors inside that channel, ordered the way our supplier comparison orders them — on what each one will show you rather than what it claims — with every column pulled from the vendor's own storefront on 13 August 2026; there is no verified SS-31 price anywhere in that set, so pricing is benchmarked on BPC-157 across the same vendors and no price column appears here.

Only the first two name their testing lab in their own site copy; on the other three you have to open the PDF and read the letterhead. Stock varies by compound, so confirm a vendor actually lists SS-31 before you compare — what these columns describe is disclosure practice, and that is the part that travels across every compound a vendor sells. Disclosure: this site earns a commission on purchases made through its links, and Peptriva is one of the vendors it links to. Every column above is a document you can open or a page you can load yourself.

We hold no verified CAS entry for SS-31, so a registry number is not the check to ask for — make the certificate carry the observed intact mass from the vendor's own mass-spec trace, the chiral-HPLC result confirming the D-amino-acid residues, and a lot number that matches the vial.

How do you verify SS-31 before you buy?

Four checks decide whether an SS-31 vial is real. Chirality on the first residue. The Dmt residue. The mass-spec reading. And the physical form. SS-31 has structural quirks most vendors aren't equipped to verify, so these matter more than usual. The standard eight criteria for any peptide vendor apply on top.

1. Confirm the D-arginine

The first residue is D-arginine, the mirror image of normal L-arginine. That D-form gives elamipretide two of its key properties. It resists breakdown by enzymes, and it crosses cell membranes to reach mitochondria.

If the synthesis used L-arginine instead, what you're holding isn't SS-31. It's a related and inactive peptide.

A lab can confirm D-arginine three ways: chiral HPLC, optical-rotation measurement, or amino-acid analysis after acid hydrolysis. A CoA mentioning none of them has skipped the most distinctive identity check this peptide has.

2. Confirm the Dmt residue

The second residue is 2',6'-dimethyltyrosine. It's a non-canonical amino acid, tyrosine with two extra methyl groups on the aromatic ring, and it isn't a standard building block. Suppliers either make it themselves or buy it from a specialty vendor.

A vendor quietly substituting regular tyrosine, which is cheaper and off the shelf, isn't producing SS-31. Our check is mass-spec at the expected mass, plus NMR or amino-acid analysis confirming Dmt specifically.

3. Mass-spec the molecule

The theoretical mass of SS-31 is 639.79 g/mol, so a CoA should report observed mass at [M+H]⁺ 640.8, within 0.3 Da. A meaningfully different number means the vial isn't SS-31.

The likely substitution is regular tyrosine in place of Dmt, which lands near 612 Da. That 28 Da gap is the two missing methyl groups, and it's easy to spot once you know to look.

4. Lyophilized only, no sprays and no patches

Every Phase III trial used reconstituted lyophilized powder as the study formulation. That covers MMPOWER-3, TAZPOWER and PROGRESS-HF. So research SS-31 should reach you as freeze-dried powder.

Capsules, sublingual sprays and transdermal patches appear in no published trial. Pre-reconstituted liquid shipped warm has already begun degrading before it arrives.

What does SS-31 cost in 2026?

SS-31 costs $80–$150 per 10 mg vial in 2026, which is high per milligram for a four-residue peptide. The length isn't the problem. Two of those four residues are non-standard, and both add real cost.

The D-arginine has to be sourced as the D-isomer specifically. The Dmt has to be synthesized or bought from a specialty supplier. Here's the full map.

• 10 mg vial: $80–$150 ($8–$15/mg). The most common retail size.
• 20 mg vial: $130–$220 ($6.50–$11/mg). Better per-mg value for animal-model work.
• 50–100 mg lots: $300–$700 ($6–$8/mg). For academic and industry research groups.
• Prescription Forzinity: $300,000–$750,000 per patient-year. That's orphan-drug pricing, not retail markup.

Below $50 per 10 mg vial, ask what got cut. The D-arginine and the Dmt are genuine synthesis costs, and the HPLC purification separating crude material from finished product costs more on top.

The low end of the SS-31 market frequently reflects substitution. L-arginine for D-arginine, regular tyrosine for Dmt, or both. What you get is a related peptide that isn't SS-31. Above $30/mg, you're paying retail margin rather than chemistry.

Is SS-31 legal to buy?

SS-31 is legal to buy as a Research Use Only reference compound, and legal to receive as Forzinity on a prescription. Before September 2025, elamipretide was a Phase III investigational drug reachable only through a trial or limited 503A compounding. The research channel hasn't changed. The approval changed three other things.

• Created the prescription Forzinity channel. Patients with confirmed Barth syndrome can now get elamipretide as a finished pharmaceutical product through specialty pharmacy, with insurance, post-marketing surveillance, and the rest of the drug infrastructure (Shirley, 2025).
• Closed most of the 503A compounded channel. 503A pharmacies generally can't produce "essentially a copy" of an FDA-approved drug. The compounded-elamipretide route that operated before approval is now largely unavailable.
• Left the research channel alone. Research Use Only labeling under 21 CFR § 809.10(b)(9) still covers chemical suppliers selling SS-31 for lab work. Approving one finished product doesn't criminalize synthesis of the underlying molecule.

For deeper context on the September 2025 approval, see our Forzinity FDA approval article.

What are the red flags when buying SS-31?

Seven things would stop us buying an SS-31 vial. Two are specific to this molecule, and both come from the residues nobody else has to worry about.

• No chirality verification on the CoA. If the lab didn't confirm D-arginine, they didn't check the most distinctive feature of this peptide.
• Mass-spec near 612 [M+H]⁺ instead of 640.8. That 28 Da gap is two missing methyl groups — the Dmt was substituted with regular tyrosine.
• "SS-31 for longevity" or senescence-reversal marketing. The only FDA-supported indication is Barth syndrome. Mouse functional data doesn't extrapolate to healthy adults.
• "Equivalent to Forzinity." Same molecule, different products, different oversight. Equivalence claims cross FDA jurisdiction.
• Capsules, sprays, or transdermal patches. Every Phase III trial used reconstituted lyophilized powder as the study formulation. Other delivery routes have not been studied in any published trial.
• Pre-reconstituted liquid without cold chain. Reconstituted SS-31 at room temperature has a much shorter shelf life than the dry powder.
• Internal-QC-only documentation. You want third-party ISO 17025 verification, not the vendor's own paperwork.

SS-31 (Elamipretide)

100 mg ≥99% pure Lyophilized

D-Arg-Dmt-Lys-Phe-NH₂ tetrapeptide, theoretical MW ~639.79. The same reference compound studied across the MMPOWER-3, TAZPOWER + 168-week OLE, and ongoing NuPOWER / ReCLAIM / PROGRESS-HF Phase III programs. COA with HPLC trace, mass-spec, and chiral verification ships with every order. Research Use Only.

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Frequently asked questions

Is SS-31 legal to buy in the USA?

Two channels, two answers. Forzinity is legal only with a Barth syndrome diagnosis, dispensed by a specialty pharmacy on a prescription. Research SS-31 from chemical suppliers is legal as a Research Use Only compound for lab work. It isn't the same product as Forzinity, and selling it for human consumption is illegal.

What's the difference between Forzinity and third-party tested SS-31?

Forzinity is the approved version, made by Stealth under cGMP. It ships through a specialty pharmacy with prescribing information, post-marketing surveillance and insurance coverage. Research SS-31 is the same tetrapeptide made by chemical suppliers under Research Use Only labeling. The molecules are nominally identical. The controls around them are not.

How much should third-party tested SS-31 cost?

You'll pay roughly $80–$150 per 10 mg vial, $130–$220 per 20 mg vial, and $300–$700 for 50–100 mg lots. SS-31 is short at four residues and expensive to make, because of the D-arginine and the Dmt. Prescription Forzinity sits in orphan-drug territory and isn't directly comparable.

What is Forzinity approved for?

The FDA granted accelerated approval in September 2025 for improvement of muscle strength in Barth syndrome patients ≥30 kg. The basis was the TAZPOWER 28-week RCT plus its 168-week open-label extension. Accelerated approval requires confirmatory trials after launch. Forzinity isn't approved for primary mitochondrial myopathy, dry AMD, heart failure, sarcopenia, or any senescence-related use.

What should an SS-31 Certificate of Analysis show?

HPLC purity ≥98% with the chromatogram. Mass-spec at observed [M+H]⁺ 640.8, against a theoretical MW of 639.79. Chiral-HPLC confirming D-arginine. NMR or amino-acid analysis confirming Dmt. Karl Fischer water content 2–8%. Counterion content, usually acetate or trifluoroacetate. And an ISO/IEC 17025-accredited lab named on the report.

SS-31 vs MOTS-c — which one for research?

Different mechanisms, different evidence tiers. SS-31 is a synthetic tetrapeptide that binds cardiolipin in the inner mitochondrial membrane, and it now holds FDA accelerated approval.

MOTS-c is a 16-residue peptide encoded by mitochondrial DNA, with proposed AMPK-related metabolic effects. It has no approval and stays an early-stage research target. We'd call SS-31's clinical program an order of magnitude more mature. Our SS-31 vs MOTS-c piece has the detail.

How should third-party tested SS-31 be stored?

Store lyophilized SS-31 at −20°C, protected from light, and it keeps for years. Once you reconstitute it, hold it at 2–8°C and use it within 30 days. The D-amino acid resists enzymes in a biological system. It won't protect the peptide from hydrolysis or oxidation sitting in solution.