On September 19, 2025, the U.S. Food and Drug Administration granted accelerated approval to Forzinity (elamipretide) injection as the first treatment for Barth syndrome, in patients weighing at least 30 kg. Barth syndrome is a rare, serious and life-threatening disease of the mitochondria (the energy-producing parts of cells). “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," said George Tidmarsh, M.D., Ph.D., Director of the FDA’s Center for Drug Evaluation and Research.
Physicochemical Properties
| Molecular Formula | C38H61N9O11 |
| Molecular Weight | 819.94 |
| Exact Mass | 819.449 |
| CAS # | 1849610-71-4 |
| Related CAS # | 736992-21-5;1334953-95-5 (acetate);2244098-12-0 (HCl); 1606994-55-1 |
| PubChem CID | 155977505 |
| Sequence | H-D-Arg-Tyr(2,6-diMe)-Lys-Phe-NH2.3CH3CO2H; D-arginyl-2,6-dimethyl-L-tyrosyl-L-lysyl-L-phenylalaninamide acetic acid |
| SequenceShortening | RXKF |
| Appearance | Solid powder |
| Hydrogen Bond Donor Count | 12 |
| Hydrogen Bond Acceptor Count | 14 |
| Rotatable Bond Count | 19 |
| Heavy Atom Count | 58 |
| Complexity | 1020 |
| Defined Atom Stereocenter Count | 4 |
| SMILES | CC1=CC(=CC(=C1C[C@@H](C(=O)N[C@@H](CCCCN)C(=O)N[C@@H](CC2=CC=CC=C2)C(=O)N)NC(=O)[C@@H](CCCN=C(N)N)N)C)O.CC(=O)O.CC(=O)O.CC(=O)O |
| InChi Key | ZTOJICBVNLHTEQ-QTSNMJAOSA-N |
| InChi Code | InChI=1S/C32H49N9O5.3C2H4O2/c1-19-15-22(42)16-20(2)23(19)18-27(41-29(44)24(34)11-8-14-38-32(36)37)31(46)39-25(12-6-7-13-33)30(45)40-26(28(35)43)17-21-9-4-3-5-10-21;3*1-2(3)4/h3-5,9-10,15-16,24-27,42H,6-8,11-14,17-18,33-34H2,1-2H3,(H2,35,43)(H,39,46)(H,40,45)(H,41,44)(H4,36,37,38);3*1H3,(H,3,4)/t24-,25+,26+,27+;;;/m1.../s1 |
| Chemical Name | acetic acid;(2S)-6-amino-2-[[(2S)-2-[[(2R)-2-amino-5-(diaminomethylideneamino)pentanoyl]amino]-3-(4-hydroxy-2,6-dimethylphenyl)propanoyl]amino]-N-[(2S)-1-amino-1-oxo-3-phenylpropan-2-yl]hexanamide |
| Synonyms | MTP-131 triacetate; Elamipretide Triacetate; 1849610-71-4; Elamipretide (triacetate); RX-31 triacetate; SS-31 triacetate |
| HS Tariff Code | 2934.99.9001 |
| Storage |
Powder-20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month Note: Please store this product in a sealed and protected environment, avoid exposure to moisture. |
| Shipping Condition | Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs) |
Biological Activity
| Targets | Cardiolipin peroxidase[1] |
| ln Vitro | Barth syndrome is a rare X-linked genetic disorder characterized by mitochondrial dysfunction. Elamipretide is a mitochondrial cardiolipin binder that penetrates cells and accumulates in the mitochondria: It localizes to the inner mitochondrial membrane, improving mitochondrial morphology and function. Elamipretide's mechanism of action involves electrostatic interactions with cardiolipin, a phospholipid critical for mitochondrial structure and electron transport chain function. By binding to cardiolipin, elamipretide stabilizes the mitochondrial membrane, prevents oxidative damage, and maintains membrane potential. This interaction preserves cristae integrity, reduces reactive oxygen species (ROS) production, and maintains ATP production. Elamipretide also enhances the activity of mitochondrial respiratory complexes, facilitating efficient electron transfer and ATP synthesis. Furthermore, elamipretide inhibits the opening of the mitochondrial permeability transition pore (mPTP), protecting against mitochondrial damage during reperfusion and reducing cell death in ischemic conditions. |
| ln Vivo |
Elamipretide triacetate (5 mg/kg, ip, once daily for 3 days) has neuroprotective effects, protects the hippocampus from mitochondrial dysfunction, and alleviates oxidative stress and inflammatory responses in a lipopolysaccharide (HY-D1056)-induced cognitive impairment model in C57BL/6 mice [1].
Elamipretide is a mitochondrial cardiolipin binder that localizes to the inner mitochondrial membrane to improve mitochondrial morphology and function. Elamipretide was shown to attenuate neuronal oxidative stress and neuroinflammation, activate neural mitochondrial biogenesis, enhance mitochondrial respiration, and protect against neural apoptosis. Protective effects of elamipretide against neuronal loss and inflammation have been reported in traumatic brain injury, hind limb ischemia–reperfusion injury, type II diabetes, and spinal cord injury. Clinically significant QTc interval prolongation was not observed at three times the peak concentration of the maximum recommended dose. Elamipretide is a mitochondrial cardiolipin binder being investigated for diseases involving mitochondrial dysfunction. Elamipretide is a synthetic tetrapeptide that selectively binds to cardiolipin, a phospholipid in the inner mitochondrial membrane. This interaction improves mitochondrial morphology and function. In September 2025, the U.S. Food and Drug Administration (FDA) granted accelerated approval for FORZINITY™ (elamipretide) to improve muscle strength in adult and pediatric patients with Barth syndrome weighing at least 30 kg. ELAMIPRETIDE is a Protein drug with a maximum clinical trial phase of III (across all indications) and has 10 investigational indications. |
| Animal Protocol |
Animal/Disease Models:LPS-induced cognitive impairment in C57BL/6 mice model[1] Doses: 5 mg/kg Route of Administration: i.p., once daily for 3 days Experimental Results: Maintained the mitochondrial function, ROS and MDA levels, and SOD activity. Inhibited neural cell apoptosis in hippocampus, enhanced the hippocampal BDNF pathway and synaptic structural complexity. |
| ADME/Pharmacokinetics |
Absorption Elamipretide exposure increases proportionally over a dose range of 2 to 80 mg following daily subcutaneous injections with minimal accumulation. Maximum elamipretide concentrations were reached between 0.5 to 1 hour after subcutaneous administration. The absolute bioavailability following subcutaneous administration is approximately 92%. Elamipretide exposure is comparable after subcutaneous injection to the thigh or to the abdomen. Route of Elimination Elamipretide and its metabolites M1 and M2 are excreted in the urine. At 48 hours post-dose, approximately 100% of the elamipretide dose was recovered in the urine as either elamipretide, M1, or M2 in patients with normal renal function. Volume of Distribution Elamipretide is distributed throughout total body water with an approximate volume of distribution of 0.5 L/kg. Protein Binding Protein binding is approximately 39%. Metabolism / Metabolites Elamipretide is metabolized via sequential C-terminal degradation to the M1 tripeptide and M2 dipeptide metabolites, which do not have pharmacological activity. The metabolic pathways have not been fully characterized. |
| References |
[1]. Elamipretide (SS-31) improves mitochondrial dysfunction, synaptic and memory impairment induced by lipopolysaccharide in mice. J Neuroinflammation. 2019 Nov 20;16(1):230. [2]. Chronic Therapy With Elamipretide (MTP-131), a Novel Mitochondria-Targeting Peptide, Improves Left Ventricular and Mitochondrial Function in Dogs With Advanced Heart Failure. Circ Heart Fail. 2016 Feb;9(2):e002206. |
| Additional Infomation | Barth syndrome primarily affects males, typically starts with severe heart failure in infancy, and causes premature death. Patients who survive into adolescence and adulthood often have fatigue, poor stamina, and exercise intolerance. The quality of life and daily functioning of patients with Barth syndrome are significantly affected throughout their lives. Forzinity works by binding to the inner part of the mitochondria, improving mitochondrial structure and function. FDA granted Forzinity accelerated approval. This pathway can allow earlier approval of medications that treat serious conditions and fill an unmet medical need on the basis of a measure that is considered reasonably likely to predict patient benefit but does not directly assess the benefit to the patient. Forzinity’s accelerated approval is based on improved strength of the muscle used to straighten the leg at the knee. FDA considers this improvement reasonably likely to predict patient benefit, such as an ability to stand more easily or walk farther. As a condition of accelerated approval, FDA is requiring the manufacturer of Forzinity to conduct a post-approval randomized, double-blind, placebo-controlled trial to confirm that the changes seen on knee muscle strength translate into patient benefit. Forzinity is administered subcutaneously (under the skin) once daily. The most common side effects identified in clinical trials were mild-to-moderate injection site reactions. Serious reactions to Forzinity have also been reported. |
Solubility Data
| Solubility (In Vitro) | H2O : ≥ 100 mg/mL (121.96 mM) DMSO : 100 mg/mL (121.96 mM; with sonication) |
| Solubility (In Vivo) |
Solubility in Formulation 1: ≥ 1 mg/mL (1.22 mM)(saturation unknown) in 10% DMSO 40% PEG300 5% Tween-80 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution This solution produces a clear solution of ≥ 1 mg/mL (saturation unknown). For example, if 1 mL of working solution, add 100 μL of 10.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix well; then add 50 μL Tween-80 to the above system and mix well; then add 450 μL saline to make up to 1 mL. *Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution. Solubility in Formulation 2: ≥ 1 mg/mL (1.22 mM)(saturation unknown) in 10% DMSO 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution, add 100 μL of 10.0 mg/mL clear DMSO stock solution to 900 μL corn oil and mix well. (Please use freshly prepared in vivo formulations for optimal results.) |
| Preparing Stock Solutions | 1 mg | 5 mg | 10 mg | |
| 1 mM | 1.2196 mL | 6.0980 mL | 12.1960 mL | |
| 5 mM | 0.2439 mL | 1.2196 mL | 2.4392 mL | |
| 10 mM | 0.1220 mL | 0.6098 mL | 1.2196 mL |