Peptides

SS-31 (Elamipretide)

Elamipretide is FDA-approved as Forzinity under accelerated approval for Barth syndrome in patients weighing at least 30 kg; broader anti-aging claims remain unestablished.

Small Barth-syndrome trial plus restricted accelerated FDA approval

Also known as: Elamipretide · Forzinity · MTP-131

Practical use

Evidence interpretation and clinical context

Use the exact approved context: Name Forzinity, Barth syndrome and the weight eligibility requirement.
Label the extension clearly: Separate open-label improvement from the randomized trial results.
Check the confirmatory evidence: Future evidence should establish whether strength changes improve outcomes that patients experience.

A phase 2/3 randomized clinical trial followed by an open-label extension to evaluate the effectiveness of elamipretide in Barth syndrome, a genetic disorder of mitochondrial cardiolipin metabolism.

US prescribing information, Forzinity

What the FDA approved — primary or official source

Overview

SS-31 is elamipretide, a mitochondrial tetrapeptide that interacts with cardiolipin in the inner mitochondrial membrane. Barth syndrome disrupts cardiolipin biology. The US indication is to improve muscle strength in adults and children with Barth syndrome who meet the weight requirement.

Risks and limitations

Injection-site reactions were common, and serious hypersensitivity reactions have been reported. Safety and benefit in a rare mitochondrial disease should not be generalized to healthy people seeking more energy or longer life.

How to read this

An accelerated approval can rest on an outcome considered likely to predict patient benefit while a confirmatory trial remains required. That is a meaningful approval with a specific evidence limitation.

Research explained

A phase 2/3 randomized clinical trial followed by an open-label extension to evaluate the effectiveness of elamipretide in Barth syndrome, a genetic disorder of mitochondrial cardiolipin metabolism.

Who was studied

A randomized placebo-controlled crossover trial in 12 people with Barth syndrome, followed by an open-label extension; eight reached the reported 36-week extension assessment.

What was found

Neither the walking-distance nor symptom primary endpoint was met in the randomized period. The extension reported improved walking distance, symptoms and other measures.

What it cannot establish

Open-label before-and-after improvement lacks the protection of the original blinded placebo comparison. Small numbers and selective continued follow-up limit certainty.

Read the original study

What the FDA approved

Forzinity received accelerated approval in September 2025 for Barth syndrome in patients weighing at least 30 kg. The decision used knee-extensor strength as an outcome reasonably likely to predict clinical benefit.

Supporting source

What remains to be confirmed

FDA requires a randomized, blinded placebo-controlled study to confirm that the strength changes translate into patient benefit. The approval does not establish general fatigue, anti-aging or athletic-performance indications.

Supporting source