SS-31: where it stands with the FDA, and what it costs
FDA-approved in 2025 as Forzinity, for one rare disease (Barth syndrome); what online clinics sell is compounded SS-31.
Go to clinicLowest per monthSS-31 injection
Try Nova · $185/mo
Go to clinicLowest at a clinic we link toSS-31 injection (10mg)
Pepti · $249/mo (≈ $267 per 30 days with its fees)
Where SS-31 stands today
Elamipretide (SS-31) is FDA-approved as FORZINITY (Stealth BioTherapeutics; NDA 215244, approved September 19, 2025), a once-daily subcutaneous injection approved under accelerated approval to improve muscle strength in patients with Barth syndrome weighing at least 30 kg; its active ingredient is elamipretide hydrochloride. Section 503A allows a bulk substance with no monograph if it is a component of an FDA-approved drug (FDA's guidance quotes this condition), so the hydrochloride does not depend on the bulks list or FDA's categories, and FDA has placed elamipretide in none. FDA told an ingredient distributor in December 2025 that elamipretide (SS-31) acetate, a different salt, is ineligible for 503A compounding, and in August 2026 it sent warning letters to four online sellers of 'SS-31' research peptides. It is not on the 503B bulks list or in any 503B category.
FDA-approved products
FORZINITY (elamipretide) injection, 280 mg/3.5 mL (80 mg/mL) vial, Stealth BioTherapeutics Inc., approved 2025-09-19 (NDA 215244). Prescription (marketed); approved under accelerated approval, to improve muscle strength in adult and pediatric patients with Barth syndrome weighing at least 30 kg.
“FORZINITY ELAMIPRETIDE HYDROCHLORIDE EQ 280MG BASE/3.5ML (EQ 80MG BASE/ML) SOLUTION;SUBCUTANEOUS Prescription ... 09/19/2025 ORIG-1 Approval”
FORZINITY label (September 2025), Stealth BioTherapeutics Inc., approved 2025-09-19 (original approval). Prescription.
“FORZINITY is indicated to improve muscle strength in adult and pediatric patients with Barth syndrome weighing at least 30 kg. This indication is approved under accelerated approval based on an improvement in knee extensor muscle strength, an intermediate clinical endpoint ... FORZINITY contains elamipretide, a mitochondrial cardiolipin binder. Elamipretide is isolated as a hydrochloride salt that is freely soluble in water.”
For pharmacies compounding one patient's prescription (section 503A)
Not in any 503A category and not on the 503A bulks list; not needed for elamipretide hydrochloride, the active ingredient of an FDA-approved drug (FORZINITY, September 2025), which is the 503A route for a substance without a monograph. FDA told an ingredient distributor in December 2025 that elamipretide (SS-31) acetate, a different salt, is ineligible for 503A compounding.
“(2) If such a monograph does not exist, are drug substances that are components of drugs approved by the Secretary of the Department of Health and Human Services (Secretary);”
FDA warning letter to Darmerica, LLC (an ingredient distributor): the acetate salt of elamipretide is ineligible for 503A compounding
“Additional APIs that you distribute or distributed to compounders seeking to operate under section 503A of the FD&C Act that are ineligible for use in human drug compounding under sections 503A include: dapoxetine hydrochloride, 2-methoxyestradiol (2ME2), tesofensine, FGL acetate aka [GLP-1]-FGL peptide acetate, thymogen, buserelin acetate, elamipretide (SS-31) acetate, larazotide acetate, and cagrilintide acetate.”
21 CFR 216.23(a), the 503A bulks list itself: six substances (Brilliant Blue G, cantharidin, diphenylcyclopropenone, N-acetyl-D-glucosamine, squaric acid dibutyl ester, thymol iodide); none of the compounds in this file
“The following bulk drug substances can be used in compounding under section 503A(b)(1)(A)(i)(III) of the Federal Food, Drug, and Cosmetic Act.”
For outsourcing facilities (section 503B)
Not on the 503B bulks list and not in any 503B category (FDA's 503B nominations list, updated March 21, 2025, does not name it)
“Outsourcing facilities, which operate under section 503B of the Federal Food, Drug, and Cosmetic Act (FD&C Act), may not compound a drug product that includes a bulk drug substance unless: The bulk drug substance appears on a list identifying bulk drug substances for which there is a clinical need (the 503B bulks list), or”
The 503B bulks list holds five substances (diphenylcyclopropenone, glycolic acid, quinacrine HCl oral, squaric acid dibutyl ester, trichloroacetic acid); none of the compounds in this file
“FDA has evaluated the following bulk drug substances and determined that there is a clinical need for outsourcing facilities to compound drug products using these bulk drug substances under section 503B of the FD&C Act:”
FDA warnings, recalls and letters
8 December 2025: Warning letter: elamipretide (SS-31) acetate is among the ingredients the firm sold to 503A pharmacies that FDA says are ineligible for 503A compounding; its listing of the ingredient also named the wrong active ingredient. (Darmerica, LLC, Davie, FL (an ingredient (API) distributor)).
“Additional APIs that you distribute or distributed to compounders seeking to operate under section 503A of the FD&C Act that are ineligible for use in human drug compounding under sections 503A include: dapoxetine hydrochloride, 2-methoxyestradiol (2ME2), tesofensine, FGL acetate aka [GLP-1]-FGL peptide acetate, thymogen, buserelin acetate, elamipretide (SS-31) acetate, larazotide acetate, and cagrilintide acetate. ... Similarly, in the listing for the drug API “Elamipretide (SS-31) Acetate” (NDC 71052-907), you list the active ingredient as peptide B27PD in the SPL.”
24 August 2026: Four warning letters dated 24 Aug 2026 to research-peptide sellers name their SS-31 (elamipretide) as an unapproved new drug (the sellers' products have no approved application). (Peptide Partners LLC (online 'research peptide' seller); same-day letters to Royal Peptides, TXP Innovations dba Tex Peptides and Peak Performance Peptides name SS-31 too).
“Based on our review,“GLP-1 S (Semaglutide),” “GLP-2 T (Tirzepatide),” “GLP-3 Reta (Retatrutide),” “SS-31 (Elamipretide),” “Tesa Peptide (Tesamorelin),” “PT-141 (Bremelanotide),” and “Reconstitution Solution (BAC)” are unapproved new drugs under section 505(a) of the Federal Food, Drug, and Cosmetic Act (FD&C Act), 21 U.S.C. 355(a).”
Our reading
A 503A pharmacy may compound elamipretide for a patient-specific prescription from elamipretide hydrochloride, the approved drug's ingredient, from an FDA-registered source, subject to 503A's other conditions, including not regularly compounding copies of the commercially available FORZINITY. SS-31 made from the acetate salt is outside 503A on FDA's own statement. Use for anything but Barth syndrome is off-label. A 503B facility has no route from bulk unless the drug is on FDA's shortage list.
Every source above was checked again on 15 November 2026.
What 10 clinics charge
- Try NovaSS-31 injection$185/mo
- BloomMDSS-31 injection (2mg/ml)$199/mo
- PeRxSS-31 injection$229for 30 days
- Zepym HealthSS-31 injection$239/mo≈ $256 per 30 days with its fees
- PeptiSS-31 injection (10mg)$249/mo≈ $267 per 30 days with its fees
What SS-31 is
- What it is
- Mitochondria-targeted tetrapeptide (cardiolipin binder)
- How it works
- A four-amino-acid peptide that binds cardiolipin, a fat of the inner membrane of mitochondria; its FDA label calls it a mitochondrial cardiolipin binder.
- How it is given
- Subcutaneous injection
- Also called
- elamipretide, Forzinity, SS31
SS-31 side by side
About SS-31
Is SS-31 FDA-approved?
Only as Forzinity, for improving muscle strength in Barth syndrome, in patients who weigh at least 30 kg (accelerated approval). What online clinics usually sell is compounded SS-31, which the FDA has not approved.
Is SS-31 legal in the US?
Whether a pharmacy may compound it for your prescription is what decides it. Elamipretide (SS-31) is FDA-approved as FORZINITY (Stealth BioTherapeutics; NDA 215244, approved September 19, 2025), a once-daily subcutaneous injection approved under accelerated approval to improve muscle strength in patients with Barth syndrome weighing at least 30 kg; its active ingredient is elamipretide hydrochloride. Section 503A allows a bulk substance with no monograph if it is a component of an FDA-approved drug (FDA's guidance quotes this condition), so the hydrochloride does not depend on the bulks list or FDA's categories, and FDA has placed elamipretide in none. FDA told an ingredient distributor in December 2025 that elamipretide (SS-31) acetate, a different salt, is ineligible for 503A compounding, and in August 2026 it sent warning letters to four online sellers of 'SS-31' research peptides. It is not on the 503B bulks list or in any 503B category.
How much does SS-31 cost?
10 clinics publish a price. The lowest that compares per month is $185/mo at Try Nova, and the middle of 5 clinics' lowest monthly prices is about $229. What a month buys differs by clinic, so each price lists what it includes. every SS-31 price
What forms does SS-31 come in?
Clinics sell it as injection (11 prices), other (1 price).