SS-31

The first mitochondria-targeting peptide the FDA has approved. It protects the membrane where energy is made.

Evidence: AApproved what's this?
Grade A for Barth syndrome (Sept 2025). Positive renal pilot; broader trials largely missed.
Also known as: Elamipretide · MTP-131 · Bendavia · Forzinity
Class: Mitochondria-targeted aromatic-cationic tetrapeptide. Approved for Barth syndrome.

The 30-second version

WhatFour amino acids that build up on the inner mitochondrial membrane and bind cardiolipin.

Proven forBarth syndrome, a rare mitochondrial disease that closely matches how it works.

The honest catchLarge trials in heart failure, myopathy and eye disease mostly missed their main goals.

What it is

SS-31 has one of the most elegant mechanisms in this guide and a deep preclinical record across heart, kidney, muscle and ageing. In large human trials it repeatedly missed its primary endpoints. Its one approval, as Forzinity in September 2025, is for Barth syndrome, an inherited cardiolipin disorder. Every other use is investigational.

How it works

Targets cardiolipin, the signature fat of the inner mitochondrial membrane.

Concentrates there within minutes, far above levels in the rest of the cell.

Stabilises cristae and keeps the electron-transport chain assembled.

More ATP, and less reactive oxygen made at the source.

Blocks cardiolipin-triggered cell death (apoptosis).

Unlike many mitochondrial antioxidants, it gets in without needing membrane charge, so it keeps working when charge collapses during injury. That’s exactly when protection matters.

What the research shows

Barth syndrome: TAZPOWER and its extension showed functional gains, especially muscle strength, which led to accelerated approval³. Kidney: in a Phase 2a trial during stent revascularisation for renal artery stenosis, kidney hypoxia rose 47% on placebo but fell 6% on elamipretide, and renal blood flow was higher at three months⁴. Elsewhere: the Phase 3 in mitochondrial myopathy missed its primary endpoints, heart-failure results were modest, and dry macular degeneration was mixed. In animals: it sped ATP recovery after kidney ischaemia, protected tubules and prevented progression from acute injury to chronic kidney disease⁵. It also reversed mitochondrial damage in heart, brain and ageing-muscle models^1,2.

FDA approval for one rare disease does not mean it works for everything.

Evidence at a glance

Use	Grade	Best evidence	Main gap	Read
Barth syndrome	AApproved	Muscle-strength improvement³	Confirmatory trial pending	Approved
Renal protection (human)	BHuman trials	Less hypoxia, more flow⁴	Small pilot	Promising
Kidney injury (animal)	ELab & animal	Prevented acute-to-chronic progression⁵	Preclinical	Strong
Heart failure, myopathy	BHuman trials	Missed primary endpoints	Largely negative	Disappointing
General longevity	DCommunity use	Extrapolated	Not tested in healthy people	Speculative

Dosing: what has been reported

Not a recommendation. These figures describe what was studied or what circulates in practice, kept separate so you can see how solid each one is. Speak with a qualified clinician before acting on any of it.

Setting	Figure	Route	Grade
Approved (Barth)	~40 mg once daily, weight-based	Subcutaneous	A
Trials, SC	0.1–2 mg/kg daily	Subcutaneous	B
Trials, IV	Heart failure 0.01–0.25 mg/kg/h over ~4 h; renal pilot 0.05 mg/kg/h during the procedure	IV	B
Community	~5–20 mg/day, often cycled	Subcutaneous	D

Research vials are not the approved drug product, so identity and purity depend entirely on the supplier’s testing.

Preparing & storing

Reconstitute with bacteriostatic water, refrigerate and don’t shake. There’s usually no immediately felt effect, because it protects mitochondria rather than stimulating.

Reported side effects

Injection-site reactions: redness, pain, itching, swelling, bruising, hives
Occasional headache
Otherwise well tolerated across a large trial programme

Who should avoid it

Pregnancy and breastfeeding
Serious heart, kidney or muscle disease: get specialist care, not self-treatment

Regulatory status checked Oct 2026

Body	Status	Detail
FDA (US)	Approved (Barth)	Forzinity, Sept 2025; accelerated approval.
EMA (EU)	Not approved	—
CDSCO (India)	Not approved	—
WADA	Not listed	IV over 100 mL / 12 h falls under the infusion rule.

The NexGen read

Beautifully targeted, narrowly proven

SS-31 protects mitochondria where it matters, and its safety record is reassuring. The kidney signal stands out. For general ageing, the human trials have mostly not delivered the benefit the mechanism promises.

References

Szeto HH. First-in-class cardiolipin-protective compound to restore mitochondrial bioenergetics. Br J Pharmacol. 2014;171(8):2029–2050.
Szeto HH, Birk AV. Serendipity and the discovery of novel compounds that restore mitochondrial plasticity. Clin Pharmacol Ther. 2014;96(6):672–683.
Reid Thompson W, et al. Elamipretide in Barth syndrome (TAZPOWER). Genet Med. 2021;23(3):471–478. FDA accelerated approval of Forzinity, 19 Sept 2025.
Saad A, Herrmann SMS, Eirin A, et al. Phase 2a trial of elamipretide during stent revascularization in atherosclerotic renal artery stenosis. Circ Cardiovasc Interv. 2017;10(9):e005487.
Szeto HH, Liu S, Soong Y, et al. Mitochondria-targeted peptide accelerates ATP recovery and reduces ischemic kidney injury. J Am Soc Nephrol. 2011;22(6):1041–1052.