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BHuman cohort / observational

SS-31

Elamipretide

SS-31 (elamipretide, formerly MTP-131, Bendavia) is a synthetic aromatic-cationic tetrapeptide (D-Arg-2',6'-dimethyl-Tyr-Lys-Phe-NH2) that concentrates in the inner mitochondrial membrane, binds cardiolipin, and is intended to stabilize mitochondrial energy production. It is an investigational drug that is not approved by the FDA or EMA for any indication; every use of gray-market 'SS-31' peptide is off-label and unregulated. Contrary to marketing as a 'longevity'/'mitochondrial-enhancement' anti-aging peptide, its pivotal human trials were largely negative: the phase-3 MMPOWER-3 trial in primary mitochondrial myopathy failed both primary endpoints, and phase-2 heart-failure (PROGRESS-HF) and topical LHON trials also missed primary endpoints. There is essentially no clinical data in healthy adults using it for performance, recovery, or anti-aging. Its most reliable finding is a favorable short-term safety/tolerability profile in supervised trials, where the dominant adverse effect is injection-site reactions. The main risks to consumers are therefore not acute drug toxicity but (1) unproven efficacy for the reasons it is sold, (2) completely unknown long-term safety in healthy people, and (3) the risks of using an unregulated, non-pharmaceutical-grade injectable of uncertain identity, purity, and sterility.

Clinical readoutPeptide · mitochondrial-peptide
Hepatic strainLow
CardiovascularNone
HPTA suppressionNone
Half-life
24 h
Route
Investigational routes…
Evidence
B
Active
Short systemic exposure…
24 h2 d3 d4 d5 d
Illustrative single-compartment washout · each mark = one half-life · t½ ≈ Short; peptide plasma half-life is on the order of a few hours. In a human heart-failure infusion trial, plasma concentrations peaked at end-infusion and were undetectable by 24 hours post-infusion.
Pharmacology

Mechanism of action

Elamipretide is a cell-permeable tetrapeptide that transiently localizes to the inner mitochondrial membrane, where it selectively associates with cardiolipin, a phospholipid essential to cristae architecture and to the assembly/efficiency of the electron transport chain (ETC) and ATP synthase. By binding cardiolipin it is proposed to protect cristae structure, promote ETC supercomplex assembly, improve electron transfer coupling and ATP output, and reduce mitochondrial reactive-oxygen-species generation and cytochrome-c peroxidase activity. It is not a hormone, receptor agonist, or enzyme inhibitor and has no androgenic, estrogenic, or SERM/aromatase activity. Human biomarker support is strongest in cardiolipin-remodeling disease (Barth syndrome), where treatment shifted the monolysocardiolipin/cardiolipin (MLCL/CL) ratio; in most other populations the downstream clinical benefit predicted by this mechanism did not materialize in controlled trials.
Kinetics

Pharmacokinetics

Half-life

Short; peptide plasma half-life is on the order of a few hours. In a human heart-failure infusion trial, plasma concentrations peaked at end-infusion and were undetectable by 24 hours post-infusion.

Active duration

Short systemic exposure supporting once-daily dosing in trials; not a depot. Detailed public PK parameters are limited.

Route

Investigational routes in trials: subcutaneous injection (40 mg/day, the form used in most myopathy/Barth trials), intravenous infusion (early dose-escalation and cardiovascular studies), and 1% topical ophthalmic solution (LHON). Gray-market products are typically sold for subcutaneous injection.

Metabolism & clearance

As a small tetrapeptide it is subject to proteolytic/peptidase degradation with renal handling/excretion of parent peptide and metabolites; it is not a substrate for the hepatic pathways typical of oral small molecules. Rapid clearance means no meaningful accumulation with daily dosing in studied populations.

For monitoring and washout planning, not drug-test evasion.

Reported effects

Physiological & performance effects

  • In supervised RCTs the most consistent finding is that subcutaneous elamipretide is well tolerated over weeks to (in a small Barth open-label extension) years.
  • Phase-3 MMPOWER-3 in primary mitochondrial myopathy did not improve 6-minute walk distance or total fatigue vs placebo (Class I evidence of no benefit).
  • Smaller/earlier signals (MMPOWER phase 1/2 dose-escalation and MMPOWER-2 crossover) suggested possible short-term exercise/fatigue effects but did not reach the pre-specified primary endpoint, and were not confirmed in phase 3.
  • In heart failure with reduced ejection fraction, a single high-dose IV infusion produced transient favorable reductions in LV volumes, but repeated subcutaneous dosing (PROGRESS-HF) did not improve LV end-systolic volume or ejection fraction.
  • In Barth syndrome, long-term open-label use was associated with improved 6MWT, fatigue, and some cardiac/biomarker measures, but this was an uncontrolled extension in a very small (n=10) rare-disease cohort.
  • In atherosclerotic renal-artery stenosis undergoing stenting, adjunctive IV elamipretide was associated with attenuated post-procedure hypoxia and improved renal blood flow in a small pilot.
  • No demonstrated ergogenic, body-composition, strength, or anti-aging effect in healthy adults — these uses are unstudied.
Safety

Adverse effects by system

Cardiovascular

No serious cardiovascular adverse events, and blood pressure and heart rate remained stable, in dedicated heart-failure infusion studies; drug-related AE rates were similar to placebo in PROGRESS-HF. No proarrhythmic or QT signal has been reported. Cardiovascular effects in trials were neutral-to-favorable, but there are no data in healthy users or with unregulated product.

Hepatic

No hepatotoxicity signal has been reported in the human trials; as a rapidly cleared peptide it is not expected to stress hepatic metabolism. Liver injury has not been systematically characterized, so absence of a reported signal is not proof of safety.

Endocrine / HPTA

Elamipretide is not a hormonal agent and has no known effect on the hypothalamic-pituitary-testicular/-gonadal axis, testosterone, estradiol, LH/FSH, thyroid, or cortisol. No endocrine adverse effects have been reported in trials.

Reproductive

No human reproductive, fertility, pregnancy, or lactation data exist. Effects on sperm, menstrual function, pregnancy, and the developing fetus are unknown; it should be treated as contraindicated in pregnancy/breastfeeding by default.

Neuropsychiatric

No psychiatric or neuropsychiatric adverse effects (mood change, anxiety, insomnia, psychosis) have been reported in the controlled trials. There is no evidence of a neuropsychiatric risk, but this endpoint was not a focus of study.

Renal

No nephrotoxicity signal; in a small renal-artery-stenosis pilot, adjunctive IV elamipretide was associated with improved renal blood flow and eGFR rather than harm. Because the peptide is renally handled, renal impairment could alter exposure, but this has not been formally characterized in the public literature.

Hematologic

No clinically significant hematologic abnormalities (anemia, leukopenia, thrombocytosis, polycythemia) have been reported, but hematologic parameters were not a primary focus and are not well characterized; treat as limited/no data rather than proven safe.

Dermatologic

Injection-site reactions are the most common adverse event with subcutaneous dosing — reported in up to ~80% of participants in MMPOWER-2 — including erythema, pain, pruritus, and induration; the large majority were mild and self-limited. This is the dominant tolerability issue for anyone injecting it.

Recovery

HPTA suppression & recovery

Suppression: None expected / not applicable

Elamipretide is a non-hormonal mitochondrial-targeted peptide with no known action on the hypothalamic-pituitary-gonadal axis and no androgenic, estrogenic, or SERM activity, so it is not expected to suppress endogenous testosterone or require post-cycle recovery. No SERM or any post-cycle therapy is indicated or discussed for this compound. Anyone experiencing symptoms of hormonal dysfunction (low libido, fatigue, testicular changes, menstrual changes) while using it should not self-treat and should be evaluated by a physician/endocrinologist to identify the true cause.

Bloodwork & vitals

Monitoring

Recommended labs & checks
Baseline and periodic comprehensive metabolic panel including renal function (creatinine, eGFR)Liver function tests (baseline and periodic, as general due diligence for any injectable of unknown provenance)Complete blood countBecause gray-market injectables carry infection/contamination risk: inflammatory markers and clinical assessment if systemic symptoms occur

Cadence: Establish a baseline before any use, then recheck at roughly 8-12 weeks and if any new symptoms arise; all monitoring should be arranged with and interpreted by a licensed clinician, not self-directed.

Warning signs — seek care
  • Spreading, worsening, or infected-appearing injection-site reaction (increasing pain, warmth, pus, fever) — stop and seek care
  • Signs of a systemic allergic/hypersensitivity reaction (rash, swelling, wheeze, throat tightness) — seek emergency care
  • New or worsening chest pain, palpitations, shortness of breath, or syncope
  • New or worsening swelling, or a marked change in urine output (possible renal issue)
  • Any unexplained systemic symptoms after injecting an unregulated product (fever, chills, malaise)
Do not use if

Contraindications

  • Pregnancy and breastfeeding (no human reproductive or developmental safety data)
  • Known hypersensitivity to elamipretide or excipients
  • Use of any non-pharmaceutical-grade / research-only 'SS-31' product of unverified identity, purity, or sterility (a practical contraindication given no approved supply exists)
  • Reliance on it in place of evidence-based medical treatment for a diagnosed cardiac, neuromuscular, renal, or ophthalmic condition
  • Injecting into inflamed, infected, or broken skin (injection-site reactions are already the dominant adverse effect)
Combinations

Interaction profile

  • ContraindicatedWith DNP: Additive cardiovascular strain

Check a specific combination in the interaction checker.

Harm reduction

Reducing harm & when to stop

  • Understand the core mismatch: elamipretide is studied in rare mitochondrial diseases, not in healthy adults for performance or anti-aging, and its most rigorous trials were negative. There is no evidence it does what the 'SS-31' longevity marketing claims.
  • There is no approved or quality-controlled supply; any product obtained is research-grade of unverified identity, dose, purity, and sterility, which is itself the main practical hazard (contamination, endotoxin, mislabeling).
  • If used at all, do so under a physician's supervision with baseline and follow-up bloodwork (renal function, CBC, LFTs) rather than self-directed dosing.
  • Injection-site reactions are the expected, dominant side effect; rotate sites, use sterile technique, and never inject into inflamed or infected skin.
  • Stop and seek medical care for spreading/infected injection sites, fever or systemic symptoms after injecting, signs of allergic reaction (rash, swelling, breathing difficulty), or new chest pain, palpitations, or breathlessness.
  • Do not use in pregnancy or while breastfeeding, and do not substitute it for evidence-based treatment of any diagnosed heart, muscle, kidney, or eye condition.
  • Report the specific product and dose to your clinician; because long-term safety in healthy people is entirely unknown, the conservative choice is to avoid use outside a formal clinical trial.
Evidence

Citations (10)

Every clinical claim above is tied to a primary source. Overall evidence grade B — graded to the best available evidence for its core claims.

  1. 01

    Elamipretide is an aromatic-cationic tetrapeptide that penetrates cell membranes, localizes to the inner mitochondrial membrane, and associates with cardiolipin.

    RCTRandomized dose-escalation trial of elamipretide in adults with primary mitochondrial myopathy.PMID 29500292 ↗

  2. 02

    The pivotal phase-3 MMPOWER-3 trial (N=218) of 40 mg/day subcutaneous elamipretide in primary mitochondrial myopathy did not meet its primary endpoints (6-minute walk test and PMMSA total fatigue) and provided Class I evidence of no benefit, while being well tolerated with mostly mild-to-moderate adverse events.

    RCTEfficacy and Safety of Elamipretide in Individuals With Primary Mitochondrial Myopathy: The MMPOWER-3 Randomized Clinical Trial.PMID 37268435 ↗

  3. 03

    In the MMPOWER-2 crossover trial, injection-site reactions were the most commonly reported adverse events with subcutaneous elamipretide (about 80% of participants), the majority mild, with no serious adverse events or deaths.

    RCTA randomized crossover trial of elamipretide in adults with primary mitochondrial myopathy.PMID 32096613 ↗

  4. 04

    Early phase-1/2 dose-escalation (MMPOWER) with IV elamipretide showed a dose-dependent short-term increase in 6-minute walk distance without increased safety concerns, but did not reach the primary endpoint threshold and required confirmation.

    RCTRandomized dose-escalation trial of elamipretide in adults with primary mitochondrial myopathy.PMID 29500292 ↗

  5. 05

    In HFrEF, a single ascending-dose IV infusion of elamipretide produced no serious adverse events with stable blood pressure and heart rate, and transient favorable reductions in LV end-diastolic and end-systolic volumes only at the highest dose; plasma peaked at end-infusion and was undetectable by 24 hours.

    RCTNovel Mitochondria-Targeting Peptide in Heart Failure Treatment: A Randomized, Placebo-Controlled Trial of Elamipretide.PMID 29217757 ↗

  6. 06

    The PROGRESS-HF phase-2 trial of repeated 4 mg or 40 mg/day subcutaneous elamipretide did not improve LV end-systolic volume or ejection fraction versus placebo, with similar drug-related adverse-event rates across groups.

    RCTEffects of Elamipretide on Left Ventricular Function in Patients With Heart Failure With Reduced Ejection Fraction: The PROGRESS-HF Phase 2 Trial.PMID 32068002 ↗

  7. 07

    In Barth syndrome, a 168-week open-label extension of TAZPOWER (n=10, 8 completing) found elamipretide well tolerated with injection-site reactions the most common adverse event, alongside improvements in 6MWT, fatigue, cardiac volumes, and the MLCL/CL ratio in this small uncontrolled cohort.

    CohortPMID 38602181 ↗

  8. 08

    The randomized phase-2/3 TAZPOWER trial evaluated elamipretide in Barth syndrome, a disorder of mitochondrial cardiolipin metabolism.

    RCTA 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.PMID 33077895 ↗

  9. 09

    In a small pilot in atherosclerotic renal-artery stenosis, adjunctive IV elamipretide during stenting was associated with attenuated post-procedure renal hypoxia and increased renal blood flow, without a nephrotoxicity signal.

    RCTPhase 2a Clinical Trial of Mitochondrial Protection (Elamipretide) During Stent Revascularization in Patients With Atherosclerotic Renal Artery Stenosis.PMID 28916603 ↗

  10. 10

    Topical 1% elamipretide ophthalmic solution for Leber hereditary optic neuropathy was generally well tolerated with mostly mild-to-moderate, spontaneously resolving adverse events and no serious adverse events, but did not meet its primary visual-acuity endpoint.

    RCTElamipretide Topical Ophthalmic Solution for the Treatment of Subjects with Leber Hereditary Optic Neuropathy: A Randomized Trial.PMID 37923251 ↗

Last reviewed 2026-07-06 · Verified against PubMed · Educational, not medical advice