Elamipretide, widely catalogued under its research code SS-31, is a synthetic tetrapeptide with an alternating cationic/aromatic residue pattern. It contains two non-proteinogenic features: a D-arginine at position 1 and the unnatural residue 2',6'-dimethyltyrosine at position 2, with a C-terminal carboxamide. This architecture makes the peptide cell-permeable and allows it to concentrate in the inner mitochondrial membrane in a manner reported to be independent of membrane potential, distinguishing it from cationic mitochondrial probes that depend on the potential gradient.

The molecular target described in the literature is cardiolipin, the signature dimeric phospholipid of the inner mitochondrial membrane. Elamipretide binds cardiolipin reversibly and has been studied for effects on cristae architecture and on the organisation of electron transport chain supercomplexes. It has been investigated in models of ischaemia-reperfusion injury, heart failure, mitochondrial myopathy, and in Barth syndrome, a genetic condition in which tafazzin mutations reduce mature cardiolipin.

On regulatory status: elamipretide hydrochloride received FDA accelerated approval in September 2025 under the trade name Forzinity, making this a genuinely approved medicine in at least one jurisdiction. That approval should be read precisely. It rests on TAZPOWER, a randomised, double-blind, placebo-controlled crossover trial in twelve patients in which the randomised phase did not show the knee-extensor strength increase sought; the observed change came during open-label extension. Accelerated approval is a conditional pathway. Separately, trials in other mitochondrial and cardiac indications have returned mixed results. Research-grade peptide sold here is not the approved finished drug product and has not been through its manufacturing, characterisation or labelling controls.