SS-31 (Elamipretide)

What it is

A synthetic mitochondria-targeted tetrapeptide (D-Arg-Dmt-Lys-Phe-NH₂) containing two non-natural amino acids, developed by Hazel Szeto and Peter Schiller and commercialized by Stealth BioTherapeutics. SS-31 carries a +3 charge at physiological pH, enabling energy-independent accumulation at the inner mitochondrial membrane where it binds cardiolipin to stabilize cristae structure, enhance electron transport chain efficiency, and reduce reactive oxygen species. It received FDA accelerated approval in September 2025 as Forzinity for Barth syndrome, becoming the first approved therapy for this ultra-rare genetic disease. Multiple Phase 2/3 trials have been conducted in primary mitochondrial myopathy, heart failure, and dry age-related macular degeneration.

Community-reported ranges

Dosing reflects the FDA-approved Forzinity prescribing information (40 mg SC daily) and published clinical trial protocols. This is not dosing guidance for off-label use.

Frequently discussed alongside

Based on community forum discussions. Not a recommendation to combine compounds.

Published research

Elamipretide has been studied across multiple Phase 2/3 clinical trials. The pivotal TAZPOWER trial in Barth syndrome (N=12) did not meet primary endpoints in the 12-week double-blind crossover phase, but the 168-week open-label extension demonstrated clinically meaningful improvements in 6-minute walk test distance vs. natural history (79.7 m improvement at week 64, p=0.0004). MMPOWER-1 in primary mitochondrial myopathy (36 patients) showed a 44-meter placebo-adjusted improvement in 6MWT at the highest dose, but MMPOWER-3 (Phase 3) did not meet primary endpoints. In dry AMD, the ReCLAIM-2 trial (176 patients) missed primary endpoints but showed a significant 43% reduction in ellipsoid zone attenuation progression (p=0.0034). The Phase 3 ReNEW trial (360 patients, 96 weeks) is enrolling. Earlier Phase 1/2 heart failure studies showed improved left ventricular function parameters.

Reported side effects

From community self-reports. Not from controlled studies.

Clinical trial data across more than 500 subjects shows the most common adverse event is injection site reactions (pruritus, erythema, pain, swelling), which were the primary cause of discontinuation in the ReCLAIM-2 trial (17.1%). Less common events include headache, dizziness, nausea, abdominal pain, and fatigue. No serious treatment-related adverse events or deaths have been reported across the clinical program. The TAZPOWER 168-week open-label extension confirmed sustained safety over approximately 4 years of continuous use.

Regulatory status