THURSDAY, Sept. 25, 2025 (HealthDay News) -- The U.S. Food and Drug Administration granted accelerated approval to Forzinity (elamipretide) injection as the first treatment for Barth syndrome.Barth syndrome is a rare, serious, and life-threatening disease of the mitochondria and Forzinity works by binding to the inner part of the mitochondria, improving their structure and function. Forzinity is administered subcutaneously once daily.The approval is based on improved strength of the muscle used to straighten the leg at the knee, which is reasonably likely to predict patient benefit such as an ability to stand more easily or walk farther. The FDA, as a condition of accelerated approval, is requiring a postapproval randomized, double-blind, placebo-controlled trial to confirm that the changes seen on knee muscle strength translate into patient benefit. The most common side effects reported in clinical trials were mild-to-moderate injection site reactions, although serious reactions were also reported. "The FDA remains committed to facilitating the development of effective and safe therapies for rare diseases and will continue to work diligently to help ensure patients with rare diseases have access to innovative treatments," George Tidmarsh, M.D., Ph.D., director of the FDA Center for Drug Evaluation and Research, said in a statement.Accelerated approval of Forzinity was granted to Stealth Biotherapeutics.More Information.Sign up for our weekly HealthDay newsletter