SS-31

The short answer

What is SS-31 (elamipretide)?

SS-31, also called elamipretide, is a four-amino-acid peptide that concentrates in the inner mitochondrial membrane and binds cardiolipin, the phospholipid that holds the respiratory complexes in position there. The mechanism paper is precise about what that does and what it does not: in ischemic mitochondria the compound re-energized the organelle through the cardiolipin interaction, rather than by acting as a general free-radical scavenger (Birk et al., 2013). The human record sits in rare mitochondrial disease. MMPOWER-3 was a randomized clinical trial in primary mitochondrial myopathy (Karaa et al., 2023), and the TAZPOWER programme reported long-term open-label extension results in Barth syndrome, a genetic disorder of cardiolipin remodeling (Thompson et al., 2024). Peptara supplies research-grade SS-31 as a lyophilized 10mg vial for laboratory research; this page describes what published studies reported, not an effect in any person, and a qualified clinician is the only place a personal question belongs.

Applications

Common Research Areas

Evidence

What did the SS-31 trials actually study?

Two programmes carry most of the human record, and both are in rare disease. MMPOWER-3 was a randomized clinical trial of elamipretide in people with primary mitochondrial myopathy, published in Neurology (Karaa et al., 2023). TAZPOWER studied Barth syndrome, a genetic disorder of cardiolipin remodeling that lines up directly with the compound's mechanism, and reported 168-week open-label extension results (Thompson et al., 2024).

MMPOWER-3 read out negative, and that belongs in the body of the page rather than in a footnote. The trial did not meet its primary endpoints, six-minute walk distance and total fatigue score at 24 weeks, and its authors classify the result as Class I evidence that elamipretide does not improve those two measures against placebo in primary mitochondrial myopathy (Karaa et al., 2023). What the same trial did report is that subcutaneous elamipretide was well tolerated, with most adverse events mild to moderate in severity (Karaa et al., 2023).

The molecule does hold one narrow approval, under its clinical name. The FDA approved elamipretide hydrochloride as Forzinity on 19 September 2025 under application NDA 215244, and the approved label states an indication to improve muscle strength in adult and pediatric patients with Barth syndrome weighing at least 30 kg, granted under accelerated approval on an intermediate endpoint, with continued approval potentially contingent on a confirmatory trial (FDA, Drugs@FDA NDA 215244). That is a prescription medicine dispensed through a clinician. It is not this vial: what ships here is research-grade SS-31 for laboratory research, and no approval of any kind covers that.

Those populations are the boundary of the evidence, and it is worth stating plainly: no trial cited here enrolled healthy adults, and none measured aging, endurance or body composition. The mechanistic work in ischemic mitochondria is preclinical (Birk et al., 2013). Anything beyond that is extrapolation, and this page does not make it. Nothing here is medical advice.

The certificate for this batch is pending. Fourteen of the nineteen catalog SKUs carry a published third-party panel today, listed on the certificates page, and the remaining five say pending rather than showing a figure no lab has measured.

SS-31 FAQ