SS-31

SS-31 is a synthetic peptide made up of four amino acids that targets the inner mitochondrial membrane, the part of your cells where energy production actually happens. Its pharmaceutical name is elamipretide, and it was developed by Dr. Hazel Szeto at Weill Cornell Medical College. In September 2025, the FDA approved elamipretide under the brand name Forzinity for treating Barth syndrome, a rare genetic condition affecting mitochondrial function. This makes SS-31 the first mitochondria-targeted peptide to receive FDA approval for any condition.

The peptide works by binding to cardiolipin, a specialized fat molecule found almost exclusively in the inner mitochondrial membrane where it plays a critical role in energy production. Think of cardiolipin as the structural glue that holds your energy-producing machinery together. When cardiolipin becomes damaged through oxidation, a process that accelerates with age, your mitochondria leak electrons and produce less of the ATP energy your body needs. SS-31 stabilizes cardiolipin and restores normal mitochondrial function.

For people interested in health optimization and longevity, SS-31 represents a fundamentally different approach to mitochondrial support compared to other compounds. Instead of providing fuel for your mitochondria like NAD+ does, or activating metabolic pathways like MOTS-c, SS-31 repairs the actual structural damage that prevents your mitochondria from working properly in the first place. Using a car engine analogy: if NAD+ is the fuel and MOTS-c is a performance upgrade, SS-31 is the mechanic who fixes the broken engine. Pouring premium fuel into a damaged engine gives limited results, so repairing the damage first makes everything else work better.

SS-31 has been tested in 18 human clinical trials across multiple medical conditions, giving it one of the more extensive clinical track records among research peptides. It is water-soluble, crosses cell membranes easily without requiring any special transporters, and concentrates inside mitochondria at levels 5,000 times higher than in the surrounding cell fluid.

Your mitochondria produce energy through a process called the electron transport chain, which is a series of protein complexes embedded in the inner mitochondrial membrane. These complexes pass electrons along a chain, using the energy released to pump protons and ultimately generate ATP, the energy molecule that powers everything your body does. Cardiolipin is essential for this process because it holds the protein complexes together in organized structures called supercomplexes, which allow electrons to flow efficiently from one complex to the next.

When cardiolipin becomes oxidized or damaged, which happens increasingly as you age, these supercomplexes fall apart. Electrons leak out of the chain, reactive oxygen species (damaging free radicals) increase, and ATP production drops. This is one of the core mechanisms behind the energy decline, slow recovery, and metabolic dysfunction that come with aging.

SS-31 works through several mechanisms to address this problem. It binds directly to cardiolipin in the inner mitochondrial membrane, stabilizing the interaction between cardiolipin and a key protein called cytochrome c, which improves electron transfer. This reduces electron leakage and cuts reactive oxygen species production by 40 to 60 percent. It also preserves the structure of mitochondrial cristae, which are the folds in the inner membrane where ATP production takes place. The more intact these folds are, the more surface area is available for energy production.

Unlike traditional antioxidants that circulate throughout your entire body, SS-31 accumulates specifically where oxidative damage originates: inside the mitochondria themselves. This targeted approach allows it to work at concentrations that would be impossible to achieve with antioxidants you swallow. The peptide reaches peak levels in the blood within 15 minutes of administration and has an elimination half-life of approximately 2 hours.