SS-31

SS-31 is another name for elamipretide: FDA warning letters list these products as “SS-31 (Elamipretide).” It is a peptide of four amino acids (D-Arg-2,6-dimethyl-Tyr-Lys-Phe-NH2) that the Forzinity label calls a mitochondrial cardiolipin binder: it settles in the inner membrane of mitochondria and improves their shape and function. Cardiolipin is a fat in that membrane, and in Barth syndrome the gene for a protein that alters cardiolipin, TAFAZZIN, is changed. After an injection under the skin, about 92% reaches the bloodstream, levels peak within 0.5 to 1 hour, and about 100% of a dose was recovered in urine within 48 hours.

Yes, for one use. The FDA approved Forzinity (elamipretide) on September 19, 2025, “to improve muscle strength in adult and pediatric patients with Barth syndrome weighing at least 30 kg,” the first treatment approved for the disease. It had declined to approve the application in May 2025, and approved it after the company responded. This is an accelerated approval, based on an improvement in knee muscle strength, an intermediate endpoint; continued approval depends on a confirmatory trial, and the FDA may withdraw it if that trial fails to verify a clinical benefit. The application had priority review and orphan status, and Forzinity received a rare pediatric disease designation. Drugs@FDA lists no other approved use.

No. Forzinity is a prescription medicine reviewed and approved by the FDA. On August 24, 2026, the FDA told two online sellers that their “SS-31 (Elamipretide)” products, listed alongside semaglutide, tirzepatide and retatrutide, are unapproved new drugs, with no approved application in effect. Labels saying “research use only” or “not for human consumption” did not change that, because the sellers’ websites showed the products were meant for people. One letter also cited bacteriostatic water sold with a “peptide guide” and “peptide calculator” as the means to prepare an injectable drug. Elamipretide is not on the FDA’s 503A compounding category lists or its Category 2 safety-risk page (checked October 16, 2026).

Not Forzinity. It comes ready to use: a clear, colorless to yellow liquid, 280 mg in 3.5 mL (80 mg/mL), in single-patient-use vials, four to a carton, so nothing is mixed. Each vial holds more than one dose, and each 0.5 mL contains 40 mg of elamipretide. The dose is drawn in milliliters with the syringes your prescriber gives you or that come with the medicine, because the label warns the wrong syringe can cause a dosing mistake. Keep unopened vials in the fridge at 2 °C to 8 °C (36 °F to 46 °F) and don’t freeze them. After the first dose, keep the vial in the fridge or at room temperature (20 °C to 25 °C, 68 °F to 77 °F), and throw it away 8 days after first opening. Don’t use it if it is cloudy or has particles, and don’t mix anything else into the same syringe. The label lists the abdomen (at least 2 inches from the navel) and outer thigh, rotating sites daily; see injection sites and rotation and follow your prescriber. Research “SS-31” is unapproved, so we don’t show mixing math for it.

Barth syndrome is a rare genetic condition marked by an enlarged, weakened heart, estimated to affect 1 in 300,000 to 400,000 people worldwide. It is caused by changes in the TAFAZZIN gene and inherited in an X-linked recessive pattern; the Forzinity label says it is not likely to affect females. The FDA calls it “a rare, serious and life-threatening disease of the mitochondria.” Forzinity is approved for adults and children with Barth syndrome who weigh at least 30 kg. Its safety and effectiveness below 30 kg are not established, and the confirmatory trial the FDA requires will enroll patients 5 years and older.

Injection-site reactions are by far the most common: every patient in the label’s randomized trial had one on elamipretide, compared with 8 of 12 on placebo, and the FDA describes the most common reactions as mild-to-moderate injection-site reactions. Serious allergic reactions needing emergency care have been reported, sometimes months after starting, and anyone who has had one should not take it again. Eosinophil counts often rise, peaking around 90 days, without symptoms. The label says signs of an overdose are likely to be histamine-related, such as low blood pressure or feeling faint. In the larger MMPOWER-3 trial (218 adults with mitochondrial myopathy), elamipretide was well tolerated, with most side effects mild to moderate. Tell your prescriber about any reaction.