subcutaneous

SS-31 (Elamipretide)

SS-31 (Elamipretide / Forzinity / Bendavia / MTP-131)

SS-31 (Elamipretide) at a glance

Not on either FDA list

How studies gave it

Injected into the fat under the skin

Evidence on this page

3 peer-reviewed papers, published 2020 to 2025

FDA compounding lists

It appears on neither of the two FDA compounding tables.

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.

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.

What the terms on this page mean8 terms

amino acid: A building block that links with others to form peptides and proteins.
Phase 2: A mid-size trial testing whether the substance does anything useful.
clinical trial: A study that tests something in people under a written plan, with results recorded.
double-blind: Neither the participants nor the researchers know who received the real substance.
open-label: Everyone knows who received what, so expectation can colour the result.
placebo-controlled: Part of the group receives an inactive substitute for comparison.
Phase 3: A large trial, the kind regulators read before approving a drug.
Phase 1: The first test in people, usually a small group, looking mainly at safety rather than at whether it works.

Compounding status

Not on either FDA list

FDA listing: SS-31 (Elamipretide) appears on neither FDA's category 2 table nor its table of withdrawn nominations.
What that means: Absence from both lists is not permission to compound. Section 503A allows a bulk drug substance only where a USP or NF monograph exists, or the substance is a component of an FDA-approved drug product, or it appears on the 503A bulks list.

Source: Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks, FDA. Content current as of 2026-04-22; read 2026-09-05. This describes what a compounding pharmacy may supply. It is not advice about your own use.

Reading up on SS-31 (Elamipretide) is the easy part

Keeping the schedule straight is the hard part. PepKit is the app for that.

Does the reconstitution math for you
Logs each dose and reminds you when the next is due
Counts down every vial's expiration

Where this came from3 references

Each one was resolved at PubMed and confirmed to be the work this page cites. Author, title, journal and year come from the PubMed record, not from the page text.

Long-term efficacy and safety of elamipretide in patients with Barth syndrome: 168-week open-label extension results of TAZPOWER
Thompson WR, et al.. Genetics in medicine : official journal of the American College of Medical Genetics (2024). PMID 38602181.
The mitochondria-targeted peptide SS-31 binds lipid bilayers and modulates surface electrostatics as a key component of its mechanism of action
Mitchell W, et al.. The Journal of biological chemistry (2020). PMID 32273339.
Elamipretide: A Review of Its Structure, Mechanism of Action, and Therapeutic Potential
Tung C, et al.. International journal of molecular sciences (2025). PMID 39940712.

About this page

Reviewed 2026-08-11. This page reports what published studies and FDA documents say. It carries no dose, cycle length or stack, and it does not tell you whether a substance is appropriate for you. Side-effect reports circulating on forums are self-reported rather than measured, so they are not republished here.

See the editorial policy for how corrections are handled.