SS-31 / Elamipretide
Mitochondrial cardiolipin binder · elamipretide
Mitochondrial cardiolipin-binding tetrapeptide now FDA-approved as Forzinity for improving muscle strength in Barth syndrome patients weighing at least 30 kg.
Reference dose
5–10 mg daily
Source-specific educational reference, not an individualized recommendation.
Reference schedule
Daily · 8–12 weeks
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This page gets detailed quickly.
Profiles include evidence, formats, units, source-specific reference amounts and, where relevant, device details. If any of those terms are unfamiliar, do not guess your way through them. Start with a Personalised Guide and we will put the foundations in the right order for you.
At a glance
Approved name
Forzinity
Elamipretide injection received FDA accelerated approval in 2025.
Approved use
Barth syndrome
To improve muscle strength in patients weighing at least 30 kg.
Label dose
40 mg daily
Subcutaneous; renal dose modification applies in severe impairment.
Approval pathway
Accelerated approval
Confirmatory evidence is still required for continued approval.
What it is
SS-31 is the research name commonly associated with elamipretide, a synthetic tetrapeptide designed to target cardiolipin in the inner mitochondrial membrane.
Elamipretide is now the active ingredient in Forzinity, the first FDA-approved treatment for Barth syndrome, under accelerated approval.
Research focus
How it works
Elamipretide binds cardiolipin in the inner mitochondrial membrane and is intended to improve mitochondrial membrane organization and respiratory-chain function. FDA's approved indication is specific to Barth syndrome rather than general energy, longevity or performance enhancement.
Important context
The regulatory status changed materially in 2025. Elamipretide is now FDA approved as Forzinity for a narrow Barth syndrome indication, but commercial research products sold as SS-31 or elamipretide are not automatically equivalent to the approved drug.
What it is studied for
Barth syndrome research focuses on mitochondrial cardiolipin abnormalities, muscle weakness and exercise intolerance.
Broader mitochondrial-disease programmes have examined fatigue, exercise capacity and skeletal-muscle function.
Preclinical research has explored oxidative stress, mitochondrial membrane organization and energy production, but those themes should not be converted into generic longevity or performance claims.
More contextApproved for Barth syndrome, not for generic mitochondrial optimizationSee the deeper context, evidence details and practical distinctions behind this profile.
Forzinity received accelerated approval in September 2025 based on improvement in knee-extensor muscle strength, an intermediate endpoint. Continued approval may depend on confirmation of clinical benefit.
The original randomized Barth syndrome crossover trial did not meet its two primary endpoints during the blinded phase, while longer open-label follow-up showed improvements that contributed to the overall evidence package.
- The approved U.S. dose is 40 mg subcutaneously once daily in patients weighing at least 30 kg, with dose reduction for adults with severe renal impairment.
- The approved product is supplied as 280 mg/3.5 mL (80 mg/mL) solution in single-patient-use vials.
- A phase 3 trial in primary mitochondrial myopathy did not establish broad efficacy across mitochondrial disease, so Barth syndrome approval should not be generalized to healthy users or unrelated mitochondrial conditions.
- FDA warning letters in 2026 distinguished unapproved online SS-31/elamipretide products from the approved Forzinity application.
Why people are interested
What makes SS-31 / Elamipretide worth researching.
FDA-approved indication
Barth syndrome muscle strength
FDA granted accelerated approval based on improvement in knee-extensor muscle strength in the rare Barth syndrome population.
Established pharmacology
Cardiolipin-targeted mechanism
Elamipretide binds cardiolipin within the inner mitochondrial membrane, making it mechanistically distinct from generic supplements or metabolic peptides.
Small human trial + extension
Long-term Barth data
The blinded crossover phase did not meet both primary endpoints, but open-label extension data showed improvements in functional and symptom measures over longer treatment.
Human phase 3 evidence
Limits of generalization
A large phase 3 primary mitochondrial myopathy trial did not establish broad efficacy, so Barth syndrome results should not be generalized to all mitochondrial disease or healthy ageing.
Evidence
Where the evidence is strongest, and what kind of evidence it is.
Accelerated approval · 2025
FDA approval basis
Forzinity was approved to improve muscle strength in Barth syndrome patients weighing at least 30 kg based on an intermediate endpoint, with confirmatory benefit still required.
Human · randomized crossover + extension
SPIBA-201
Twelve Barth syndrome patients entered the randomized crossover trial. The blinded primary endpoints were not met, while longer open-label follow-up showed improvement in several measures.
Human · phase 3 · different disease
MMPOWER-3
In primary mitochondrial myopathy, elamipretide did not establish the broad efficacy needed to support extrapolation beyond the approved Barth syndrome indication.
Not approved-product evidence
Online research SS-31
FDA has taken enforcement action against sellers marketing SS-31/elamipretide products without approved applications; these products should not be presented as equivalent to Forzinity.
Human research
The Barth syndrome programme included a randomized double-blind placebo-controlled crossover study followed by a long-term open-label extension. The blinded primary endpoints were not met, but later extension data showed functional improvements.
FDA granted accelerated approval in 2025 based on improvement in knee-extensor muscle strength, an intermediate clinical endpoint.
A phase 3 randomized trial in primary mitochondrial myopathy did not establish broad efficacy, underscoring that the approved Barth syndrome result is disease-specific rather than a universal mitochondrial effect.
Preclinical research
Preclinical studies support interaction with cardiolipin and effects on mitochondrial membrane structure, respiratory-chain organization and oxidative stress.
These mechanisms help explain the therapeutic hypothesis but do not establish anti-ageing, athletic or healthy-person benefits.
Reference dosing
Reference amount, schedule and conversion.
A reference amount is only useful when you know the formulation, concentration and delivery device it belongs to. Do not transfer a vial amount into a pen, a pen click count into another pen, or a syringe-unit number into a different concentration.
01
Identify the format
Vial, reusable cartridge pen, prefilled multi-dose pen or single-dose autoinjector.
02
Confirm concentration
Know the total peptide amount and liquid volume or the manufacturer/vendor concentration.
03
Understand the units
Keep mg/mcg, mL and syringe units or device clicks separate.
04
Then use the reference
Only convert a known reference amount with the calculator that matches the actual device.
Source-specific reference
5–10 mg daily
Daily · 8–12 weeks
The 5–10 mg daily range is retained as a Pep Report research reference. Approved elamipretide use is a separate product-specific clinical context and follows its own label.
Calculator connection
This profile does not currently use a vial or pen calculator. Follow the formulation-specific information shown for the product or reference you are using.
Forzinity is a finished 80 mg/mL prescription product with labelled administration instructions. The generic vial calculator is intentionally disabled because approved product dosing should follow the prescribing information rather than research-vial arithmetic.
Storage
Start with the format. Then verify the exact product.
Rule of thumb, not a product instruction
Storage belongs to the exact formulation. Generic advice can orient you, but the label, pharmacy directions or formulation-specific stability data should determine the final temperature and usable-life limits.
Pens
Treat a pen as a finished drug-device product: protect it from unnecessary heat and light, do not freeze unless the exact label explicitly permits it, and use that device's own unopened and in-use storage window.
Vials
Treat dry and reconstituted vials as different stability states. Refrigeration after mixing is common for some formulations but is not a universal peptide rule.
Product-specific notes
Use the current Forzinity prescribing information for approved-product storage and handling.
Research SS-31 products should not inherit Forzinity's validated stability, purity or shelf-life assumptions.
Practical reference
Formats
Forzinity finished injection
Research SS-31 products are not equivalent
Reconstitution & units
Forzinity is supplied as a finished 80 mg/mL solution and does not require peptide-style user reconstitution.
The label states not to mix other products in the same syringe and to discard the vial eight days after first opening.
Forzinity's labelled dose is 40 mg once daily in patients weighing at least 30 kg, subject to the prescribing information and renal adjustment.
The generic vial calculator is disabled because the approved product already has a fixed validated concentration and product-specific instructions.
Safety, status & open questionsOpen the practical cautionsElamipretide is an FDA-approved prescription medicine only in the form and indication covered by Forzinity's approval. 'SS-31' sold as a research peptide is not automatically an approved product, and the approval does not establish anti-ageing, energy or performance benefits in healthy people.
Open questions
Forzinity's approval is accelerated and continued approval may depend on confirmatory evidence of clinical benefit.
The pivotal Barth syndrome population was very small because the disease is extremely rare.
Benefits demonstrated or inferred in Barth syndrome do not establish efficacy in healthy people, ageing, fatigue syndromes or unrelated mitochondrial conditions.
Unapproved research products sold as SS-31 may differ from Forzinity in identity, purity, concentration and manufacturing quality.
Regulatory notes
Forzinity (elamipretide) received FDA accelerated approval on September 19, 2025 to improve muscle strength in adult and pediatric Barth syndrome patients weighing at least 30 kg.
The approved product is not a blanket approval for all SS-31/elamipretide products or uses.
FDA warning letters in 2026 identified peptide-shop SS-31/elamipretide products as unapproved new drugs when marketed without an approved application.
Practical notes
Injection-site reactions are the most common adverse reactions and were frequent in the small Barth syndrome clinical programme.
Serious hypersensitivity reactions have been reported and are a labelled contraindication after serious hypersensitivity to elamipretide or excipients.
Eosinophil-count increases were observed with longer exposure in clinical studies.
Forzinity contains benzyl alcohol and is not approved for neonates because of benzyl-alcohol toxicity risk.
Safety and product-quality assumptions from Forzinity should not be transferred to unapproved online research products.
Common mistakes
Still calling SS-31 entirely investigational after Forzinity's 2025 FDA approval.
Treating Forzinity's approval as proof of general anti-ageing, energy or exercise-performance benefit.
Using the old 5–10 mg research range instead of the current product-specific Barth syndrome label.
Assuming online SS-31 vials are the same product as FDA-approved Forzinity.
Using a generic vial calculator for a finished approved prescription formulation.
Common questions
Is SS-31 now FDA approved?
Elamipretide is FDA approved as Forzinity under accelerated approval for improving muscle strength in Barth syndrome patients weighing at least 30 kg. That does not approve every product sold as SS-31 or every proposed use.
Why did the old Pep Report dose change?
Because there is now an approved U.S. product with a specific 40 mg once-daily label for its approved population. The old generic 5–10 mg research range is no longer the best primary reference.
Does Forzinity prove SS-31 is a longevity peptide?
No. The approval is for a rare genetic mitochondrial disease and does not establish benefits in healthy ageing or performance.
Why is the vial calculator disabled?
Forzinity is a finished 80 mg/mL prescription product with labelled preparation and administration instructions, so generic research-vial arithmetic is not appropriate.
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Open reference →References
Forzinity prescribing information
U.S. FDA / Drugs@FDA · 2025
FDA accelerated approval announcement for Barth syndrome
U.S. FDA · 2025
Elamipretide in Barth syndrome — randomized crossover + extension
PubMed · 2021
MMPOWER-3 in primary mitochondrial myopathy
Neurology / PMC · 2023
FDA Drug Trials Snapshot — Forzinity
U.S. FDA · 2025