SS-31 (Elamipretide)

Typical use cases

Dosing guidelines

Titration

Dose-escalation studies stepped subcutaneous doses upward toward 40 mg/day; clinical and community protocols are generally described as starting low and increasing gradually toward the studied maintenance range as tolerated. (Educational framing only — not dosing advice.)

Reconstitution

The FDA-approved product (Forzinity) is a ready-to-use sterile aqueous solution and does not require reconstitution. Research/lyophilized SS-31 powder, by contrast, is typically reconstituted with bacteriostatic or sterile water for subcutaneous injection (volume chosen to give a convenient per-dose concentration).

Injection sites

Subcutaneous injection — commonly the abdomen or upper thigh, rotating sites to limit injection-site reactions. (Intravenous infusion was also used in some early trials.)

Storage & handling

Per the Forzinity label, vials are stored refrigerated at 2-8°C (36-46°F) and not frozen; after the first dose the opened vial may be kept refrigerated or at room temperature and is discarded 8 days after first opening. Research-grade lyophilized powder is generally kept frozen/refrigerated until reconstituted, then refrigerated.

Side effects

• Injection-site reactions (erythema, pain, itching, induration, urticaria) Mild · Common
• Injection-site bruising Mild · Common
• Headache Mild · Uncommon
• Dizziness Mild · Uncommon
• Gastrointestinal upset (nausea, diarrhea) Mild · Uncommon
• Hypersensitivity / allergic-type reaction Moderate · Rare

Research summary

Elamipretide is one of the most clinically studied mitochondria-targeted peptides, with a mechanism centered on selective binding to cardiolipin in the inner mitochondrial membrane, which is reported to stabilize electron-transport-chain supercomplexes, improve the cytochrome c interaction, reduce reactive oxygen species, and support ATP synthesis. Extensive preclinical work across heart failure, ischemia-reperfusion, aging, and neurodegeneration models showed restoration of mitochondrial bioenergetics and reduced oxidative damage. Human evidence is mixed: in primary mitochondrial myopathy, an early crossover study (MMPOWER-2) reported significant improvement in patient-reported fatigue while the 6-minute-walk-test primary endpoint did not reach statistical significance, and the larger Phase 3 MMPOWER-3 trial failed to meet its primary endpoints. Cardiovascular trials (e.g., PROGRESS-HF, ischemia-reperfusion studies) and the ReCLAIM/ReCLAIM-2 studies in dry age-related macular degeneration and geographic atrophy likewise produced inconsistent or negative primary results. The most definitive human signal came in Barth syndrome, where data from the TAZPOWER program supported FDA accelerated approval of elamipretide HCl (Forzinity, Stealth BioTherapeutics) in September 2025 to improve muscle strength in patients weighing at least 30 kg — the first disease-specific therapy for Barth syndrome. Overall the compound is generally well tolerated, with injection-site reactions being the most common adverse event; key limitations include small rare-disease trial populations, reliance on intermediate/surrogate endpoints, and several failed efficacy readouts in larger indications. Much of the longevity and anti-aging interest remains extrapolated from preclinical and mechanistic data rather than confirmed in healthy humans.

Key references

• https://pmc.ncbi.nlm.nih.gov/articles/PMC11816484/
• https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/215244s000lbl.pdf
• https://pubmed.ncbi.nlm.nih.gov/41335372/
• https://pmc.ncbi.nlm.nih.gov/articles/PMC7432581/
• https://www.fda.gov/news-events/press-announcements/fda-grants-accelerated-approval-first-treatment-barth-syndrome
• https://www.selleckchem.com/products/elamipretide-ss-31-mtp-131-antioxidant-peptide.html

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