SS-31 (Elamipretide / MTP-131)
Boosts your cells' energy production at the source. A mitochondria-targeting peptide that concentrates in the inner mitochondrial membrane to support ATP production, FDA-approved in 2025 as FORZINITY for Barth syndrome, the first mitochondria-targeted drug, with all other uses off-label.
SS-31 (Elamipretide / MTP-131): Boosts your cells' energy production at the source. A mitochondria-targeting peptide that concentrates in the inner mitochondrial membrane to support ATP production, FDA-approved in 2025 as FORZINITY for Barth syndrome, the first mitochondria-targeted drug, with all other uses off-label. SS-31 (also called Elamipretide or MTP-131) targets your mitochondria, the energy plants inside your cells.
SS-31 (also called Elamipretide or MTP-131) targets your mitochondria, the energy plants inside your cells. It concentrates in the inner mitochondrial membrane and supports ATP production. Used by people with mitochondrial-flavored fatigue and as a longevity adjunct.
FDA-approved as FORZINITY (elamipretide) on Sept 19, 2025 under accelerated approval, to improve muscle strength in adult and pediatric Barth syndrome patients weighing >=30 kg. The first FDA-approved mitochondria-targeted drug. Approved only for Barth syndrome, every other use (longevity, general mitochondrial support) is off-label and unapproved.
FDA-approved drug products containing this substance are available. Compounded versions are not FDA-approved.
Yes for Barth syndrome (FORZINITY, 40 mg sub-q daily), via specialty pharmacy. Not commercially available for off-label longevity use.
Who it's for
- →Users with mitochondrial-flavored fatigue
- →Older adults targeting cellular bioenergetics
- →Stack add-ons for hard-training athletes
What to expect
- Week 1
Subtle. Some users notice fatigue lifting first.
- Week 4
Cumulative endurance / recovery improvements for responders.
- Week 8
Plateau. Cycle off.
Looking at SS-31 (Elamipretide / MTP-131)? Your next 3 steps
- 1Work out your syringe units
Vial size + BAC water turns into the exact units to draw for SS-31 (Elamipretide / MTP-131).
Open calculator → - 2See what to stack & monitor
The companion supplements and the bloodwork worth tracking on this kind of protocol.
Bloodwork guide → - 3Save it & ask the Coach
A free account gets you Coach questions every day, free; membership saves your stack and makes the Coach stack-aware.
Create free account →
How it works (mechanism)
Mitochondria-targeted peptide that concentrates in the inner mitochondrial membrane and binds cardiolipin. Stabilizes the electron transport chain and improves ATP production efficiency under stress.
Dosing protocol
Stacks well with
Side effects
When NOT to use
- ⚠Pregnancy / nursing
- ⚠No data in active malignancy
Common mistakes
- • Expecting fast effects (it's cumulative)
- • Running short cycles and quitting before adaptation
- • Underdosing for therapeutic context
What it actually is
SS-31, also called elamipretide or MTP-131, is a four-amino-acid peptide that concentrates in the inner mitochondrial membrane. It is the first mitochondria-targeted drug to reach approval: FDA granted it accelerated approval in 2025 as Forzinity, for improving muscle strength in eligible patients with Barth syndrome — a rare genetic disorder of the same membrane lipid it binds. Accelerated approval means confirmatory evidence is still owed. Every other use — and there are many being marketed — is off-label and unapproved.
The inner mitochondrial membrane contains a distinctive lipid called cardiolipin, which organises the proteins that carry out energy production. When cardiolipin is damaged or abnormal, that machinery becomes inefficient and leaks reactive oxygen species. SS-31 binds cardiolipin and appears to stabilise the arrangement, improving the efficiency of ATP production and reducing oxidative leak. Barth syndrome is a disorder of cardiolipin remodelling specifically, which is why that is where it worked first and best.
Forms, and which is which
Approved in 2025 for Barth syndrome. Daily subcutaneous injection under specialist care.
Verdict: The only regulated form, for a rare disease.
Buyer reconstitutes. Research-chemical supply with unverified identity, at doses extrapolated from trials in unrelated conditions.
Verdict: The common route, and the dose is guesswork.
Combines it with MOTS-c or humanin, neither of which has established human efficacy.
Verdict: One approved compound diluted into several unknowns.
Not absorbed intact as an active dose.
Verdict: Not plausible by the route claimed.
What it is claimed to do, graded
The approved indication, granted under accelerated approval, which is a lower evidentiary bar than a full approval and carries a confirmatory obligation. Read the claim as that specific endpoint in that specific population.
Well demonstrated mechanistically and across a large preclinical literature. As a general human benefit outside Barth syndrome it is not established.
The reason most off-label use happens. No trial supports it, and someone without a mitochondrial disorder has no established deficit for it to correct.
Worth stating plainly: this was studied in a large randomised programme and the primary endpoints were not met. It is the reason the approval that came was for a much narrower indication.
No human data. The mitochondrial theory of ageing is a hypothesis, not a demonstrated target.
Grades describe how much human evidence exists for that specific claim, not whether it will work for you or whether it is safe.
Pros and cons
- • Actually approved, on genuinely novel pharmacology — a drug designed to act at the inner mitochondrial membrane
- • A substantial preclinical literature across several organ systems
- • Very well tolerated in the trials
- • 17 indexed randomised-trial records and 5 phase 3 records, which is a real programme
- • The approval is for one rare genetic disease, and nearly all use is far outside it
- • The larger primary mitochondrial myopathy programme did not meet its endpoints
- • Off-label dosing is extrapolated from trials in unrelated conditions
- • Research-chemical supply for non-prescribed use, with unverified identity
- • Expensive as the approved product
When to stop
- • Injection-site reaction that spreads
- • No change after a full course in whatever you were tracking
- • Any new cancer diagnosis
- • You are treating a suspected mitochondrial disorder without a diagnosis
Interactions
Stacking makes any effect unattributable, and none of the others has established human efficacy.
Improving mitochondrial efficiency in a body with a tumour is unstudied in either direction.
Listed because mitochondrial function and glucose handling are linked, not because any clinical interaction has been established.
Not an interaction. Exercise is the intervention with real evidence for mitochondrial biogenesis.
Interaction data comes from the approved indication, not from the uses people put it to.
Is this for you?
- • People with Barth syndrome, under specialist care
- • Anyone interested in the first approved drug that targets mitochondria directly
- • You are taking it for general energy or fatigue — that use has no supporting trial
- • You have active cancer
- • You are pregnant or nursing
- • You are extrapolating a dose from a trial in a condition you do not have
The one number
Sources for the claims above
- Improves mitochondrial dysfunction and memory impairment in a neuroinflammation model
- Attenuates idiopathic pulmonary fibrosis in a model system
- Alleviates ferroptosis in hypoxia/reoxygenation cardiomyocytes
New to SS-31 (Elamipretide / MTP-131)? Grab the starter checklist.
Drop your email and we'll send the one-page starter checklist beginners actually need first. No account needed.
No spam, and we never sell your email. Just the checklist. Email support@pepdex.co to opt out any time.
Numbers redacted in this preview. Members get the full answer, on their own stack.
Ask the Coach anything about SS-31 (Elamipretide / MTP-131) or your own stack. This is it working.
Trained only on Pepdex content. Does the dose math, flags interactions, knows your stack. Won't push vendors, won't pretend to be a doctor.
Unlock the full Coach, from $4.99/week →Frequently asked
What is SS-31 (Elamipretide / MTP-131)?+
Is SS-31 (Elamipretide / MTP-131) FDA approved?+
Is SS-31 (Elamipretide / MTP-131) legal?+
Is SS-31 (Elamipretide / MTP-131) banned by WADA?+
Are you still natty after taking SS-31 (Elamipretide / MTP-131)?+
Do doctors prescribe SS-31 (Elamipretide / MTP-131)?+
What's the typical dose of SS-31 (Elamipretide / MTP-131)?+
What are the side effects of SS-31 (Elamipretide / MTP-131)?+
How long until SS-31 (Elamipretide / MTP-131) starts working?+
What can you stack with SS-31 (Elamipretide / MTP-131)?+
Where do people get SS-31 (Elamipretide / MTP-131)?+
Common questions about SS-31 (Elamipretide / MTP-131)
Tracked alongside SS-31 (Elamipretide / MTP-131)
Same goal, different aisle — each graded on its own evidence in the Pepdex catalog.
More in Metabolic
Used clinically to boost fertility and restart the body's own testosterone production after a suppressive cycle. It's a glycoprotein hormone that works by mimicking LH at the testicular Leydig cell.
Aimed at metabolism and exercise performance. A mitochondrial-derived peptide that targets metabolic flexibility, insulin sensitivity, and exercise response.