SS-31

SS-31 (elamipretide, also called MTP-131 and formerly Bendavia) is a synthetic four-amino-acid peptide built to enter mitochondria and bind to a membrane lipid called cardiolipin ¹. That binding stabilizes the inner mitochondrial membrane, reduces oxidative stress, and supports ATP production ¹.

In 2025 the FDA granted accelerated approval to elamipretide as FORZINITY for improving muscle strength in Barth syndrome, an ultrarare X-linked disorder of cardiolipin remodeling ². Outside that indication, SS-31 is studied for heart failure, aging-related muscle and vascular decline, metabolic liver disease, diabetic kidney disease, neuroinflammation, and other conditions where mitochondria are stressed ⁸. The human evidence for those uses is still far behind the Barth syndrome data.

What the research covers

• Mechanism: cardiolipin binding, membrane stabilization, and improved energy output ¹
• Approved use: Barth syndrome muscle weakness, supported by the 2025 approval and a published pediatric case ²
• Investigational areas: heart failure, aging, metabolism, and neuroprotection, mostly from animal models ⁷
• Open questions: dose finding in adults, long-term safety, and whether bioenergetic improvements translate into function ⁹

SS-31 is a short, positively charged peptide that accumulates at the inner mitochondrial membrane and binds directly to cardiolipin, a phospholipid found almost exclusively in mitochondria ¹. Cardiolipin anchors the folded inner-membrane structures called cristae and helps the protein complexes that generate ATP stay organized ¹.

That makes the main effect structural stabilization, not broad radical scavenging ¹. In human kidney cells exposed to cadmium, 0.1 µM elamipretide reversed membrane stiffening, restored about 30% of lost respiratory supercomplexes, and cut hydrogen peroxide production by about 30% ²³. In aged muscle mitochondria, SS-31 also binds the adenine nucleotide translocator (ANT) and ATP synthase, raising ADP uptake and restoring respiration ⁷. In failing dog heart cells, a one-hour exposure to 0.1 µM produced the largest increase in ADP-stimulated respiration ²⁴.

Secondary mechanisms include:

• Inflammasome control: SS-31 upregulates Nrf2 and suppresses NLRP3 inflammasome activation, which lowered IL-1β and IL-18 in a lung fibrosis model ¹².
• Anti-senescence: 1 µM for 7 days reduced senescence markers in radiation-exposed heart cells, from 67% to 38% positive ¹⁵.
• Neuroprotection: it restored BDNF signaling and memory-related outcomes in neuroinflammation models ¹⁷.
• Vascular aging: 8 weeks of treatment restored aortic mitochondrial respiration and reduced elastin damage in aged mice ¹⁶.

The cleanest human signal is in Barth syndrome. A 2026 case report described a 5-year-old whose left ventricular ejection fraction improved from 20% to 50% after six months of 10 mg/day subcutaneous elamipretide, along with gains that allowed a return to full-time school ².

Preclinical effects reported in the literature:

• Skeletal muscle: in a rat model of heart failure with preserved ejection fraction, 12 weeks of SS-31 raised soleus whole-muscle force by 8.2% and single-fiber force by 173%, and prevented fiber loss ⁸.
• Aging muscle and aorta: in aged rodents, SS-31 restored ADP sensitivity in muscle mitochondria and normalized aortic mitochondrial respiration while reducing elastin breaks ⁷.
• Metabolic protection: in aged mice with fatty liver, 3 mg/kg/day preserved mitochondrial structure, reduced steatosis, and improved insulin signaling ¹⁰; in diabetic mice it reduced albuminuria and kidney damage ¹¹.
• Neuroprotection: SS-31 rescued memory and hippocampal mitochondrial function after neuroinflammation or surgery plus opioids in animal models ¹³, and SS-31 plus NMN reduced brain injury after experimental stroke ¹⁴.

There is an important caution. In a human heart failure study, elamipretide improved myocardial energy metabolism without translating into functional benefit ⁹. Most longevity and performance claims still rest on animal data rather than controlled human trials.

Human dosing data are sparse. The published case used 10 mg/day subcutaneous elamipretide for at least six months in a 5-year-old with Barth syndrome ⁶. In adults, no published dose-finding study exists in the reviewed evidence; community protocols generally use 10-40 mg subcutaneous once daily in 4-12 week cycles, with breaks between cycles. These doses are extrapolated from the pediatric case and animal work, not from a randomized adult trial.

Dose context:

Daily subcutaneous dose	Approximate mg/kg for a 70 kg adult
10 mg	0.14 mg/kg
20 mg	0.29 mg/kg
40 mg	0.57 mg/kg

For comparison, efficacy in a mouse metabolic model came from 3 mg/kg/day intraperitoneally ¹⁰, which converts to a human equivalent of roughly 0.24 mg/kg/day with standard allometric scaling. The pediatric case ran at about 0.5 mg/kg/day ⁶.

Route notes: subcutaneous is the only clinically documented human route ⁶. Oral free peptide is limited by rapid renal clearance and poor exposure ¹⁹, and engineered formulations are being studied to improve delivery. Animal models used intraperitoneal or parenteral routes ⁸.

The interactive timeline on this page shows the common community protocol; it is a research pattern, not an established adult dosing recommendation.

Research-grade lyophilized SS-31 is typically reconstituted with bacteriostatic water. The FDA-approved product is supplied as a ready-to-use subcutaneous injection and does not require reconstitution ².

Handling guidance from community practice:

• Add the diluent slowly down the wall of the vial; do not shake or vortex the peptide.
• Roll the vial gently until the powder dissolves.
• Keep lyophilized vials frozen at -20°C for long-term storage; refrigeration is acceptable for shorter periods.
• After mixing, store the solution at 2-8°C and use it within about 28 days.
• Protect the peptide from light and avoid repeated freeze-thaw cycles.

SS-31 contains no disulfide bonds, so its stability depends less on redox state than many other peptides. These are qualitative handling points; use the calculator below to work out specific diluent and dose volumes for a given vial.

No formal drug interaction trials have been published for SS-31. The guidance below is assembled from a pediatric case, preclinical co-administration studies, and mechanistic pharmacology.

• Heart failure medications: a 5-year-old took subcutaneous elamipretide 10 mg/day alongside standard heart failure therapy for six months without attributable toxicity; the only event was transient pancreatic enzyme elevation ⁶.
• Perioperative opioids: in aged rats, SS-31 rescued memory and mitochondrial function after surgery and morphine exposure ¹³.
• Anthracyclines and radiation: SS-31 reduced doxorubicin-induced and radiation-induced senescence in heart cells in vitro ¹⁵; these interactions are theoretical but protective in direction.
• NMN: the best-evidenced combination. SS-31 plus NMN outperformed either treatment alone in a mouse ischemic stroke model through reduced neuroinflammation ¹⁴.
• MitoQ: in a fatty liver model, MitoQ mainly raised antioxidant defenses while SS-31 better preserved mitochondrial structure ¹⁰; they are complementary rather than interchangeable.
• NAC and CoQ10/idebenone: NAC acts as a thiol antioxidant while SS-31 stabilizes cardiolipin, a distinct mechanism ²⁹. CoQ10 and idebenone share overlapping bioenergetic support, so redundancy is likely.

One theoretical caution follows from the mechanism. SS-31 preserves physiological superoxide signaling in diabetic kidney models ¹¹, so stacking multiple strong antioxidants could blunt redox signals the body uses for adaptation. No human co-administration data test this.

Published human use of SS-31 is continuous, not cycled. The approved Barth indication involves ongoing subcutaneous therapy ², and the pediatric case continued 10 mg/day for at least six months with accumulating benefit ⁶. Animal efficacy courses have run 8 to 16 weeks ⁸.

Community protocols often add breaks, typically 4 to 12 weeks on at 10-40 mg subcutaneous once daily followed by 2 to 4 weeks off. This is not because SS-31 causes tolerance. It is a structural stabilizer, not a receptor agonist, and no tachyphylaxis or withdrawal syndrome is documented. Cycling appears to be precautionary and practical, related to cost, reassessment, and the risk of unverified product quality ²⁰.

The best support for time-limited courses comes from animal work showing durable benefit after a short intervention. SS-31 started four weeks after surgery rescued memory and mitochondrial respiration in aged rats ¹³. Reassessment at the end of a cycle is also consistent with the human heart failure data, in which improved bioenergetics did not always become functional benefit ⁹.

SS-31 is commonly used as the mitochondrial component in stacks, combined with compounds aimed at repair, metabolism, or NAD+ support.

• SS-31 + NMN: the most evidence-supported stack. In a mouse stroke model, the combination reduced brain injury better than either agent alone through NF-κB/TREM2 suppression ¹⁴.
• SS-31 + MitoQ: complementary mechanisms in a fatty liver model; MitoQ mainly increased antioxidant defenses while SS-31 preserved mitochondrial structure ¹⁰. Combining them may be redundant for simple mitochondrial support.
• SS-31 + MOTS-c: both are mitochondrial-targeting peptides marketed for performance, with no co-administration data and likely overlap ²⁰.
• SS-31 + BPC-157 or TB-500: a common community approach pairing mitochondrial stabilization with repair signaling. No interaction data exist, and the human safety evidence for all three is weak ²⁰.
• SS-31 + GLP-1 agonists: distinct mechanisms, metabolic signaling versus mitochondrial stabilization; no identified conflict in the reviewed mechanistic evidence ²¹.

SS-31 is FDA approved through the accelerated pathway as elamipretide (FORZINITY) for improving muscle strength in Barth syndrome ². This 2025 approval was the first for a cardiolipin-directed mitochondrial therapy in the United States ².

All other uses remain off-label or investigational. Aging, performance, and general mitochondrial support are not approved indications, and the products sold for those uses often come through unregulated gray-market channels with unverified purity and dosing ²⁰. In the reviewed evidence there is no EMA approval; access outside the US has appeared only through compassionate use, such as a published pediatric case in France ⁶.

Regulatory notes:

• DEA scheduling: SS-31 is not a controlled substance in the reviewed literature.
• WADA: SS-31 is not named on the Prohibited List in the reviewed evidence. Before its 2025 approval it would have met the S0 class for unapproved substances; after approval that class no longer applies. The main doping risk is contamination in gray-market products, not the substance itself ²⁰.

The published safety experience for SS-31 is limited but generally reassuring in the approved setting. A pediatric patient on 10 mg/day for six months had no serious adverse events; the one notable finding was a transient, asymptomatic pancreatic enzyme elevation that resolved without stopping treatment ⁶.

Commonly reported effects:

• Injection-site reactions with daily subcutaneous dosing are the most expected issue (practitioner consensus).
• Mild fatigue or headache appears in user reports but is not represented in published trials (community consensus).

What remains unknown:

• Long-term human safety beyond about six months.
• Safety in healthy users, because all human data come from disease populations.
• Formal drug interactions, pregnancy, lactation, and infant use.
• Effects of chronic dosing on normal mitochondrial quality control and redox signaling.

Preclinical studies have generally been favorable, but gray-market sourcing adds real risk from unverified purity and sterility ²⁰. There is also a dose-response ceiling in isolated heart cells, where respiration peaked at 0.1 µM and was lower at higher concentrations ²⁴, which supports using the smallest effective research dose rather than escalating. Because of the pancreatic enzyme signal, baseline and periodic amylase/lipase checks appear in monitoring practice ⁶.