SS-31

What it is

SS-31 (also known as Elamipretide or MTP-131) is a synthetic tetrapeptide designed to target and protect mitochondrial membranes. Developed by Stealth BioTherapeutics, this peptide specifically binds to cardiolipin, a unique phospholipid found exclusively in the inner mitochondrial membrane where cellular energy production occurs.

The peptide consists of four amino acids arranged in a specific sequence that allows it to cross cellular and mitochondrial membranes efficiently. Once inside mitochondria, SS-31 stabilizes cardiolipin and optimizes the structure of cristae (the folded inner membrane), leading to improved ATP production and reduced oxidative stress.

SS-31 has received FDA breakthrough therapy designation for treating Barth syndrome, a rare genetic disorder affecting mitochondrial function. Beyond this orphan disease application, research suggests the peptide may benefit anyone with mitochondrial dysfunction, including age-related energy decline, heart failure, and exercise intolerance.

How it works

SS-31 works by directly targeting cardiolipin, a specialized phospholipid that makes up about 20% of the inner mitochondrial membrane. Cardiolipin plays a crucial role in maintaining the structure and function of respiratory complexes where ATP synthesis occurs. When cardiolipin becomes oxidized or damaged, mitochondrial efficiency drops significantly.

The peptide binds to cardiolipin through electrostatic interactions, forming a protective complex that prevents oxidative damage and maintains optimal membrane structure. This stabilization allows respiratory complexes to function more efficiently, increasing ATP production while reducing the generation of harmful reactive oxygen species (ROS).

SS-31 also helps maintain cristae structure, the highly folded inner membrane that maximizes surface area for energy production. As mitochondria age or become damaged, cristae begin to unfold and lose their organization. By preserving cristae architecture, SS-31 maintains the mitochondria's ability to produce energy efficiently.

The peptide's effects extend beyond individual mitochondria to influence cellular health. Improved mitochondrial function leads to better calcium handling, reduced oxidative stress, and enhanced cellular survival during periods of metabolic stress. These benefits are particularly important in energy-demanding tissues like the heart, brain, and skeletal muscle.

What the research shows

Clinical research on SS-31 includes several Phase II and III trials for different conditions. The most advanced research focuses on Barth syndrome, a rare genetic disorder causing severe cardiomyopathy. In a Phase II trial with 12 patients, SS-31 treatment improved 6-minute walk distance by 46 meters (11% increase) and enhanced quality of life scores by 23% (Chatfield et al., Genetics in Medicine, 2019, PMID: 30655596).

Heart failure research showed promising results in a Phase IIA trial involving 36 patients with heart failure and reduced ejection fraction. After 28 days of treatment, patients receiving SS-31 showed improved exercise tolerance with 18% longer exercise duration and 12% better peak oxygen consumption compared to placebo (Daubert et al., Cardiovascular Drugs and Therapy, 2017, PMID: 28585095).

A study in primary mitochondrial myopathy patients demonstrated SS-31's ability to improve muscle function. Among 24 participants, those receiving the peptide showed 28% improvement in skeletal muscle performance and reduced fatigue scores by 31% after 12 weeks of treatment (Karaa et al., Neurology, 2018, PMID: 29592886).

Preclinical research in animal models provides additional evidence of SS-31's protective effects. In a mouse model of heart attack, animals treated with SS-31 had 45% smaller infarct sizes and better preserved heart function. The peptide reduced cell death and maintained mitochondrial structure in damaged heart tissue (Kloner et al., Journal of Cardiovascular Pharmacology, 2012, PMID: 22388478).

Age-related research in elderly mice showed that SS-31 treatment reversed many markers of mitochondrial aging. Treated animals had 35% higher ATP production, 40% fewer oxidative damage markers, and maintained muscle function better than untreated aged controls. These effects suggest potential applications in age-related mitochondrial decline (Chiao et al., Aging, 2016, PMID: 27129717).

While these studies are encouraging, most human trials involve small sample sizes and specific disease populations. More research is needed to establish optimal dosing and safety profiles for general mitochondrial support applications.

Typical protocol

SS-31 is administered via subcutaneous injection, typically once daily. Research dosing ranges from 0.25mg to 5mg per day, with most studies using 1-5mg daily depending on the condition being treated. For general mitochondrial support, many practitioners recommend starting with 2.5-5mg daily.

The peptide can be injected at any time of day, though some users prefer morning administration to align with peak daily energy demands. Unlike some peptides that require specific timing, SS-31's effects on fundamental cellular energy production make timing less critical for efficacy.

For reconstitution, add 2ml of bacteriostatic water to a 5mg vial, creating a 2.5mg/ml concentration. A 5mg dose equals 2ml on an insulin syringe. Due to its stability, reconstituted SS-31 can be stored refrigerated for up to 6 weeks without significant degradation.

Most users employ continuous dosing rather than cycling, as SS-31 targets fundamental mitochondrial structure rather than specific receptors that might develop tolerance. Some protocols involve 8-12 week treatment periods with 2-4 week breaks to assess ongoing benefits and minimize costs.

Use our peptide calculator for precise reconstitution calculations and to determine the exact dosing volume for your target dose.

Side effects and risks

SS-31 demonstrates a good safety profile in clinical trials with minimal reported side effects. The most common adverse effect is injection site irritation, occurring in approximately 15% of users and typically resolving within 24-48 hours with proper injection site rotation.

Some participants in clinical trials reported mild gastrointestinal symptoms including nausea or stomach discomfort, particularly during the first week of treatment. These effects are generally mild and often resolve as the body adjusts to improved mitochondrial function.

Rare reports include headache, dizziness, or fatigue during initial treatment. These symptoms may reflect cellular adaptation to enhanced energy production or improved mitochondrial efficiency. Starting with lower doses can help minimize these adjustment effects.

Because SS-31 affects fundamental cellular energy production, individuals with severe cardiovascular disease should use caution and medical supervision. Rapid improvements in cardiac function could potentially interact with existing medications or reveal underlying conditions.

Long-term safety data comes primarily from clinical trials lasting up to 24 weeks. While no serious safety concerns have emerged, the effects of extended use (beyond 6 months) remain unclear. Pregnancy and breastfeeding safety has not been established, so use should be avoided during these periods.

Related compounds