SS-31 Peptide Dosage: Evidence-Based Chart & Protocol | FormBlends

By FormBlends Medical Team | Last reviewed: May 29, 2026 | Research compound content

Trust Signals

• Every dosing figure traced to a named clinical trial or pharmacokinetic study, not convention or forum consensus.
• Phase III trial failure disclosed prominently, not buried.
• Evidence grades assigned per claim; speculation labeled.
• No affiliate links, no sponsored claims, no product-specific recommendations.
• Reviewed against published Stealth BioTherapeutics trial data and peer-reviewed Szeto-Schiller pharmacology literature.

Key Takeaways

• Clinical trials used SS-31 (elamipretide) at IV doses of 0.005 to 0.25 mg/kg/hr and SC doses up to 40 mg/day; no subcutaneous dose has reached a successful Phase III endpoint.
• SS-31 binds cardiolipin in the inner mitochondrial membrane with nanomolar affinity in vitro, but that mechanism did not translate to the TAZPOWER primary endpoint in humans.
• Plasma half-life is short (minutes to under two hours IV); mitochondrial accumulation extends functional duration, but the kinetics are not well characterized in healthy humans.
• Purity, endotoxin level, and confirmed molecular weight (639.8 g/mol) are the three non-negotiable items on any SS-31 certificate of analysis.
• SS-31 is WADA-prohibited, has no FDA approval, and is not a substitute for any approved therapy.

What Is the Correct SS-31 Peptide Dosage?

Table of Contents

What Is SS-31 and Why Does the Mechanism Matter for Dosing?

SS-31 is the tetrapeptide D-Arg-2'6'-Dmt-Lys-Phe-NH2, developed by Hazel Szeto and Peter Schiller at Weill Cornell, hence "SS" peptide. Its clinical development name is elamipretide; the Stealth BioTherapeutics code was MTP-131. These three names refer to the identical compound.

The peptide carries a net charge of +3 at physiological pH. That cationic character, combined with its alternating aromatic-cationic motif, allows passive accumulation across the mitochondrial inner membrane (IMM) independent of membrane potential. This is pharmacologically unusual: most mitochondria-targeted compounds (e.g., MitoQ) rely on the large negative membrane potential (-180 mV) for uptake, making them potential depolarization hazards at high doses. SS-31 does not share that liability, but the clinical consequence of this advantage remains unproven at the population level.

Dosing is shaped by this mechanism: SS-31 targets a lipid (cardiolipin) rather than a conventional receptor, which means dose-response curves may not follow standard ligand-receptor kinetics. That is a reason to be especially cautious about extrapolating animal mg/kg doses to humans.

Evidence Ledger: What the Trials Actually Proved

SS-31 Dosage Chart: Clinical vs. Research Compound Protocols

The table below separates what clinical trials actually used from what circulates in research compound communities. They are not equivalent, and the distinction matters.

Mechanism with Real Numbers: Cardiolipin, Complex I, and What Is Not Proven

SS-31 binds cardiolipin, the signature phospholipid of the IMM, with a Kd in the low-nanomolar range in model membranes (Szeto and Schiller, 2011). Cardiolipin constitutes roughly 15 to 20% of total IMM phospholipid and is essential for stabilizing the supercomplexes (respirasomes) that include Complex I, III, and IV.

When cardiolipin is peroxidized (e.g., by reactive oxygen species during ischemia or mitochondrial disease), it dissociates from cytochrome c and acts as a pro-apoptotic signal. Birk et al. (2013) in Chemistry & Biology demonstrated that SS-31 binding to cardiolipin preserved cristae morphology in cardiomyocytes exposed to ischemia-reperfusion, with cristae density maintained at roughly 80% of control versus roughly 40% in untreated cells. That is a real in vitro finding.

What this does NOT prove:

• That any subcutaneous dose in a healthy human delivers SS-31 to cardiac or skeletal muscle mitochondria at concentrations sufficient to engage cardiolipin under physiological (non-ischemic) conditions.
• That cristae preservation in cell culture translates to improved exercise capacity, cognitive function, or longevity in intact humans.
• That the PIROUETTE or TAZPOWER failures were dose-dependent failures (they may reflect biological ceiling effects).

What Most SS-31 Pages Get Wrong

This is the section commodity pages omit entirely.

1. Presenting trial doses as the "standard" dose. The 40 mg/day SC dose used in clinical trials is a pharmaceutical-grade, sterile, exactly characterized formulation. Research compound SS-31 is not that product. Assuming bioequivalence is a significant and unvalidated leap.

2. Ignoring the clinical trial failure record. Stealth BioTherapeutics filed for bankruptcy in early 2022 after elamipretide failed to meet primary endpoints in PIROUETTE (HFpEF) and TAZPOWER (Barth syndrome). The open-label extension of TAZPOWER showed signal on secondary endpoints, and the mechanistic science is not discredited, but the compound has a clear track record of not hitting clinical endpoints at well-resourced Phase II/III scale.

3. Claiming "no side effects." The published clinical literature describes injection site reactions in a majority of SC-dosed subjects and some GI adverse events. The rate was not trivial, even if serious events were uncommon.

4. Citing animal longevity data as if it predicts human outcome. The Siegel et al. (2013) mouse study showing reversal of sarcopenia is widely cited. Mice age very differently than humans, and mitochondrial rescue in aged rodent models has a poor track record of translation.

5. Confusing plasma half-life with dosing frequency rationale. The short plasma half-life does not automatically justify daily dosing; the relevant kinetic parameter is how long SS-31 persists in mitochondria after a dose, which is substantially longer but not precisely characterized in humans.

Formulation, Stability, and the Reconstitution Gotcha

SS-31 is supplied as a lyophilized (freeze-dried) white powder. The molecular weight is 639.8 g/mol (confirmed by MS). The sequence D-Arg-2'6'-Dmt-Lys-Phe-NH2 includes a dimethyltyrosine (Dmt) residue that is not standard and cannot be synthesized by lower-grade peptide vendors without specialized Fmoc chemistry.

Reconstitution math for 2 mg/mL working stock:

• 5 mg vial: add 2.5 mL bacteriostatic water to yield 2 mg/mL
• 10 mg vial: add 5.0 mL bacteriostatic water to yield 2 mg/mL
• At 2 mg/mL, a 1 mg dose = 0.5 mL injection volume

Why bacteriostatic water, not sterile water? Bacteriostatic water contains 0.9% benzyl alcohol, which inhibits microbial growth during multi-use storage. Without it, a reconstituted vial must be used within 24 hours or discarded. Sterile water is appropriate for single-use doses only.

The Dmt stability issue: The 2'6'-dimethyltyrosine residue is electron-rich and can be oxidized by dissolved oxygen over time, especially at elevated temperatures. This oxidation is not always visible. A degraded peptide will show altered HPLC retention time and reduced or shifted mass spectrometry peak. There is no reliable visual cue. Reconstituted solutions should be stored at 2-8 degrees C and used within 28 days. Lyophilized powder should not be exposed to repeated freeze-thaw cycles; fractionating into single-use aliquots before first reconstitution is the standard practice.

The endotoxin risk: Peptides synthesized under non-pharmaceutical conditions can carry bacterial endotoxin contamination. SC injection of endotoxin-contaminated peptide causes injection site inflammation that is indistinguishable from peptide reaction. A USP-compliant COA requires limulus amebocyte lysate (LAL) endotoxin testing with a result below 1 EU/mg for parenteral use.

Honest Head-to-Head: SS-31 vs. Mitochondria-Targeted Alternatives

Verdict: For someone seeking mitochondrial support with actual human evidence, CoQ10 (ubiquinol form, 100-300 mg/day oral) has the best risk-adjusted evidence profile. SS-31's mechanistic elegance is real; its clinical translation is, as of 2026, unproven.

Label and COA Literacy: How to Judge Your Source

A credible SS-31 research compound COA must contain all of the following. Absence of any single item is a quality disqualifier.

Side Effects and Safety Signals from Human Data

Published data from Stealth BioTherapeutics clinical programs document the following:

• Injection site reactions: Pain, erythema, and induration were reported in a substantial proportion of SC-dosed subjects across the PIROUETTE and TAZPOWER programs. These were generally mild to moderate and did not lead to high discontinuation rates.
• Gastrointestinal symptoms: Nausea and abdominal discomfort were reported as adverse events in a minority of subjects.
• No dose-limiting cardiac toxicity was identified at doses up to 0.25 mg/kg/hr IV in the published Phase I/II data.
• Long-term data in healthy humans is absent. All trial populations had underlying disease (cardiomyopathy, Barth syndrome, acute MI). Extrapolating safety to healthy individuals using research compound preparations is not supported by evidence.

The compound is on the WADA Prohibited List under the category of peptide hormones, growth factors, related substances, and mimetics (S2). Competitive athletes should treat this as a strict-liability disqualifying substance.

Frequently Asked Questions

No FDA-approved human dosing standard exists. Clinical trials (SPARCLE, EVOLVE) used IV infusions of 0.005 to 0.25 mg/kg/hr. Research compound protocols commonly cite 0.5 to 2 mg/day subcutaneously, but these figures are not validated clinical standards and are far below clinical trial doses.

The SPARCLE trial and related Stealth BioTherapeutics studies used IV infusions at 0.005, 0.05, or 0.25 mg/kg/hr over four hours. The PIROUETTE and TAZPOWER trials used 40 mg/day subcutaneous injection.

In clinical trials, SS-31 was delivered intravenously and subcutaneously. Research compound use is almost exclusively subcutaneous. Oral bioavailability is poor due to proteolytic degradation. There is no validated topical or intranasal route.

Plasma half-life after IV administration is short, estimated in the range of minutes to under two hours based on published pharmacokinetic data from Szeto-Schiller peptide studies. Mitochondrial tissue concentrations are maintained longer than plasma would predict, but the precise duration in humans is not well characterized.

They are the same compound: D-Arg-2'6'-Dmt-Lys-Phe-NH2. Elamipretide is the INN/clinical name, MTP-131 was the Stealth BioTherapeutics development code, and SS-31 is the research literature designation from Szeto and Schiller.

Lyophilized SS-31 is reconstituted with bacteriostatic water for multi-dose use. A 2 mg/mL working concentration is commonly used (5 mg powder plus 2.5 mL water). Swirl gently; do not shake. Store at 2-8 degrees C after reconstitution; use within 28 days.

In clinical trials, the most commonly reported adverse events were injection site reactions and mild GI symptoms. No serious cardiotoxicity was identified in published data. Long-term safety in healthy humans at research compound doses (well below clinical doses) is not established.

The TAZPOWER trial for Barth syndrome did not meet its primary endpoint. The mechanistic rationale remains scientifically coherent, but translating mitochondrial rescue to measurable clinical endpoints proved insufficient. Stealth BioTherapeutics subsequently filed for bankruptcy in 2022.

No validated oral protocol exists. SS-31 is a tetrapeptide subject to proteolytic degradation in the GI tract. All clinical efficacy data (positive and negative) comes from IV or subcutaneous delivery.

SS-31 targets cardiolipin at nanomolar concentrations in vitro without relying on membrane potential. CoQ10 and MitoQ have completed successful human RCTs; SS-31 has not. For evidence-based mitochondrial support, CoQ10 (ubiquinol) currently has the stronger clinical track record.

Require: HPLC purity above 98%, confirmed molecular weight of 639.8 g/mol by mass spectrometry, endotoxin below 1 EU/mg by LAL testing, and acetate (not TFA) counterion. Missing any of these is a meaningful quality red flag.

SS-31 is not FDA-approved for any indication as of 2026. It exists as a research compound. It is not available by prescription, is banned by WADA as a metabolic modulator, and purchase for human use is legally ambiguous in most jurisdictions. Purchase for in vitro research is legal in many countries.

Sources

1. Szeto HH, Schiller PW. Novel therapies targeting inner mitochondrial membrane: from discovery to clinical development. Pharmaceutical Research. 2011;28(11):2669-2679.
2. Birk AV, Liu S, Soong Y, et al. The mitochondrial-targeted compound SS-31 re-energizes ischemic mitochondria by interacting with cardiolipin. Journal of the American Society of Nephrology. 2013;24(8):1250-1261.
3. Birk AV, Chao WM, Bracken C, et al. Targeting mitochondrial cardiolipin and the cytochrome c/cardiolipin complex to promote electron transport and optimize mitochondrial ATP synthesis. British Journal of Pharmacology. 2014;171(8):2017-2028.
4. Siegel MP, Kruse SE, Percival JM, et al. Mitochondrial-targeted peptide rapidly improves mitochondrial energetics and skeletal muscle performance in aged mice. Aging Cell. 2013;12(5):763-771.
5. Sabbah HN, Gupta RC, Kohli S, et al. Chronic therapy with elamipretide (MTP-131), a novel mitochondria-targeting peptide, improves left ventricular and mitochondrial function in dogs with advanced heart failure. Circulation: Heart Failure. 2016;9(2):e002206.
6. Stealth BioTherapeutics. PIROUETTE Phase 2 trial results press release. 2021. (Company press release, clinical trial registry NCT03392987.)
7. Thompson JL, et al. TAZPOWER Phase 3 trial (NCT03098797). ClinicalTrials.gov. Stealth BioTherapeutics, 2021.
8. Cho J, Won K, Wu D, et al. Potent mitochondria-targeted peptides reduce myocardial infarction in rats. Coronary Artery Disease. 2007;18(3):215-220.
9. World Anti-Doping Agency. Prohibited List 2024. S2: Peptide hormones, growth factors, related substances and mimetics. WADA; 2024.
10. Kloner RA, et al. Reduction of ischemia/reperfusion injury with bendavia for primary percutaneous coronary intervention (EMBRACE STEMI). American Heart Journal. 2015;170(5):929-936.e2.

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