Last updated: April 2026
SS-31 (elamipretide) is the most studied mitochondria-targeted peptide in existence. It's the only one with Phase 2 human trial data for heart failure, and it works by a completely different mechanism than anything else in the peptide space — by directly stabilizing cardiolipin in the inner mitochondrial membrane.
SS-31 doesn't just reach mitochondria — it concentrates specifically in the inner mitochondrial membrane (IMM), where cardiolipin lives. This targeting is the key to its activity.
Cardiolipin is a unique phospholipid found almost exclusively in the inner mitochondrial membrane. It's essential for organizing the electron transport chain complexes and anchoring cytochrome c. When cardiolipin oxidizes (from ROS damage), the ETC falls apart. SS-31 directly binds cardiolipin and prevents this oxidation.
By preserving cardiolipin, SS-31 maintains the efficiency of ETC Complexes I, III, and IV — the ATP-producing machinery. In aging cells and damaged tissue, ETC efficiency drops and electron leak increases (creating superoxide). SS-31 restores ETC coupling and reduces electron leak by up to 70% in some models.
SS-31 isn't a traditional antioxidant — it doesn't scavenge ROS directly. Instead, it prevents the source: electron leak from damaged ETC complexes. This is more effective than downstream scavenging. Cells produce less superoxide rather than cleaning it up after the fact. In cardiac ischemia models, ROS production drops dramatically.
Mitochondrial cristae (the inner membrane folds) are where ATP synthesis happens. Their geometry matters — the deeper the folds, the more ETC surface area. SS-31 preserves cristae architecture under stress conditions. In aging studies, treated mitochondria maintain younger morphology compared to untreated controls.
SS-31 has been studied across multiple disease areas. Evidence strength varies — human trials exist for heart failure, while other areas are preclinical only.
SS-31/elamipretide is unique among research peptides — it actually reached Phase 2 human trials. Here's what the data showed.
28-day randomized trial in HFpEF patients. Elamipretide at 0.05 mg/kg/hr subcutaneous infusion showed improvement in 6-minute walk test distance and reductions in NT-proBNP. The primary endpoint was achieved. This was Phase 2 — safety and preliminary efficacy only, but it was real human data.
Larger randomized trial investigating elamipretide in HFpEF. Doses of 40 mg/day subcutaneous. The trial showed safety and tolerability with some efficacy signals but didn't reach all secondary endpoints. Development was eventually paused by Stealth BioTherapeutics due to funding issues, not safety concerns.
Small trials in Barth Syndrome (rare mitochondrial cardiomyopathy) showed meaningful improvements in exercise capacity and heart function. This rare disease population had some of the most dramatic responses — patients with severe mitochondrial dysfunction showed real functional gains.
Phase 2 trials confirm safety and detect preliminary efficacy signals — they're not definitive proof. Elamipretide showed enough to be promising but development stalled at Phase 2/3 boundary. The compound is genuine and the mechanism is real — but "showed results in Phase 2" is not the same as "proven to work."
SS-31 must be administered subcutaneously or intravenously — it is not orally bioavailable. Research dosing is extrapolated from animal studies and limited human trial data.
| Context | Dose | Route | Frequency |
|---|---|---|---|
| Human HFpEF trials (STARLITE) | 0.05 mg/kg/hr (~40 mg/day for 80kg) | SubQ infusion | Continuous (28 days) |
| Human trial — single dose studies | 0.1–0.25 mg/kg | SubQ injection | Once daily |
| Animal studies (therapeutic range) | 0.1–3 mg/kg | IP/IV/SubQ | Daily or twice daily |
| Research compound use (self-reported) | 5–10 mg per injection | SubQ | Daily or 5 days/week |
| High-dose protocols (anecdotal) | 10–20 mg | SubQ | Daily |
SS-31 is a small tetrapeptide — relatively easy to synthesize but easy to fake with fragments or impurities. Always verify purity from vendor COAs. For research-grade SS-31, look for HPLC purity >98% and mass spec verification. Swiss Chems offers third-party tested peptides.
SS-31 showed a favorable safety profile in human trials. The main adverse effects are injection-related, not systemic.
In Phase 2 trials, elamipretide was well-tolerated. No serious cardiac events, hepatotoxicity, or nephrotoxicity were attributable to the drug. The safety profile was the main success of these trials — the compound doesn't appear to cause harm at therapeutic doses.
The primary adverse effect in trials was injection site reactions — erythema (redness), pruritus (itching), and induration (hardening). These were dose-dependent and generally mild. With continuous subcutaneous infusion, site rotation is essential to minimize reactions. Most resolved within 48-72 hours.
No significant drug-drug interactions have been identified. SS-31 doesn't appear to affect CYP450 enzymes. It doesn't bind plasma proteins significantly and is rapidly metabolized. For people on complex cardiac medication regimens, no interactions were identified in the HFpEF trials.
Long-term data beyond 3-6 months is limited. Effects in healthy individuals (vs. disease populations) are unknown. The trials enrolled sick patients — effects in healthy people optimizing mitochondrial function are extrapolated, not directly studied. This is the standard caveat for all research peptides.
Frequency data from Phase 2 trial reports (STARLITE, EVOLUTION-HF) and community reports. Injection site reactions dominate — no systemic toxicity was established.
Evidence-backed mitochondrial support supplements commonly paired with SS-31 protocols in longevity and biohacking contexts.
SS-31 / elamipretide is a research compound not approved by the FDA for human use outside of clinical trials. This content is for educational and informational purposes only and does not constitute medical advice. Consult a qualified physician before using any research compound. HighPeptides makes no claims about efficacy or safety for personal use.