What is SS-31, and how does it work?
SS-31, formally named elamipretide and also known as MTP-131 (Mitochondria-Targeting Peptide 131), is a synthetic tetrapeptide — a four-amino-acid chain — designed to selectively accumulate in the inner mitochondrial membrane. The "SS" designation stands for Szeto-Schiller, after the researchers who first characterized this class of membrane-permeable, mitochondria-targeted peptides.
Its mechanism centers on cardiolipin, an anionic phospholipid concentrated in the inner mitochondrial membrane and critical for mitochondrial energy production. Cardiolipin normally anchors the protein complexes that form the electron transport chain; oxidative damage to cardiolipin disrupts this architecture and reduces ATP output. SS-31 binds cardiolipin via electrostatic interactions, stabilizing the mitochondrial cristae structure, reducing local reactive oxygen species, and improving the efficiency of ATP synthesis — without requiring the peptide to enter the mitochondrial matrix.
In preclinical models of aging, heart failure, and mitochondrial disease, this mechanism translates into improved mitochondrial bioenergetics, reduced cell death from energy failure, and partial restoration of age-associated functional decline. SS-31 is not a nutrient, a hormone, or an FDA-approved drug; it is an investigational compound whose full clinical safety and efficacy profile is still being established in controlled trials.
What doses have been used in clinical trials?
Elamipretide has been studied in several human trials under a range of dose regimens. The dosing approach varies by indication and route of administration:
In heart failure with reduced ejection fraction (HFrEF), intravenous infusion doses of 0.005–0.05 mg/kg/hour over four hours were used in acute and sub-acute trial settings. For chronic administration, subcutaneous delivery has been the preferred route; the PROGRESS-HF phase 2 program tested daily subcutaneous doses in the 0.05–0.25 mg/kg/day range. In Barth syndrome (the TAZPOWER randomized trial), participants received subcutaneous elamipretide at approximately 40 mg/day — a fixed-dose protocol rather than a weight-adjusted one.
Preclinical rodent studies — from which much of the mechanistic data is derived — typically used intraperitoneal doses of 3–5 mg/kg/day. These animal figures cannot be directly scaled to human dosing; pharmacokinetic parameters (bioavailability, tissue distribution, elimination half-life) differ meaningfully between species. Each clinical trial establishes its protocol-specific titration through formal dose-ranging and safety-monitoring review; there is no universally agreed human dose for any application.
Is SS-31 FDA-approved for any condition?
As of 2026, elamipretide (SS-31) is not approved by the FDA for any indication. It holds investigational new drug (IND) status and has received FDA Orphan Drug designation for Barth syndrome and primary mitochondrial myopathy — designations that expedite the review process but do not constitute approval. No IND or NDA has been converted to a marketed approval.
Because elamipretide is not approved, there is no legal supply channel outside of a clinical trial. Material marketed online as "SS-31 research peptide" or "elamipretide peptide" is outside the FDA-regulated supply chain — identity, potency, sterility, and endotoxin levels are not verified by any FDA-oversight process. For an injectable compound, endotoxin contamination is a genuine safety risk (it can trigger fever, inflammation, and, at high doses, systemic inflammatory response). This consideration applies to any injectable peptide purchased outside a licensed pharmacy or trial supply chain.
What are the side effects and safety signals from trials?
In trials conducted to date, elamipretide has generally been well tolerated within tested dose ranges. The most frequently reported adverse events were injection-site reactions — redness, bruising, and soreness at the subcutaneous injection site — and transient gastrointestinal symptoms including nausea. Serious adverse events attributable directly to the drug were uncommon in phase 2 datasets, though the aggregate patient-exposure is still limited relative to any approved drug.
Longer-term and higher-dose safety data continue to accumulate in ongoing trials. Because SS-31 targets mitochondria systemically, there are theoretical concerns about effects on highly metabolically active tissues (cardiac and skeletal muscle, kidney, liver) at doses above those evaluated in completed studies. The formal dose-escalation and safety-monitoring structures of clinical trials are the mechanism for characterizing those risks rigorously — none of which applies to uncontrolled use outside a supervised protocol.
Tracking an SS-31 protocol on PeptidePanel
PeptidePanel does not sell, source, supply, endorse, or prescribe SS-31 or any compound. Nothing on this page is medical advice. If a licensed clinician has enrolled you in a clinical trial involving elamipretide, or is supervising an authorized investigational protocol, the value of systematic tracking is real: a dose log with timestamps, biomarker trends (cardiac function markers, inflammatory markers, mitochondrial-function proxies), and side-effect notes give you and your clinician a clear longitudinal picture of how the protocol is progressing.
PeptidePanel is the neutral monitoring layer for exactly that record-keeping — logging the protocol as directed by your clinician, charting relevant bloodwork against reference ranges, and flagging when labs or doses are due.