SS-31 (Elamipretide): Reference Overview and Reconstitution Notes

SS-31 (elamipretide) is a short chain of four amino acids that targets the cell's energy-making structures, called mitochondria. It is studied as a research compound in the area of cellular energy and mitochondrial function. The FDA has approved it for one rare disease called Barth syndrome. For all other uses, it is still investigational, meaning it is still being studied and has not been approved.

SS-31 (Elamipretide)

What it is

SS-31 (elamipretide, also known as MTP-131 or Bendavia) is a small molecule made of four amino acids linked together. A molecule built from four amino acids is called a tetrapeptide ("tetra" means four). It belongs to a family of molecules called the Szeto-Schiller (SS) peptides. SS-31 can pass through the outer wall of a cell and travel to the mitochondria (the tiny structures inside cells that make energy, like a cell's power plant). Once inside, it collects at the inner wall of the mitochondria and attaches to a fatty molecule there called cardiolipin.

Research context and categorization

SS-31 is grouped with research compounds studied for their effects on cellular energy and how mitochondria work. It is also sometimes placed in a broader group of agents studied for effects on metabolism and tissue protection. Its most important feature is that it binds to cardiolipin on the inner wall of the mitochondria. Researchers study how that attachment affects the shape of the inner wall (which has tiny folds called cristae), the flow of electrons through the mitochondria, damage from unstable molecules (called oxidative stress), and the production of adenosine triphosphate (ATP). ATP is the main fuel packet of the cell. Think of ATP as tiny charged batteries that power nearly everything a cell needs to do.

Investigational Areas

In laboratory and clinical research, SS-31 has been studied across a range of conditions tied to mitochondria not working properly. It is commonly discussed in relation to:

• Heart failure and cardiomyopathy (disease of the heart muscle)
• Ischemia and reperfusion injury (damage from blocked and then restored blood flow)
• Kidney disease
• Skeletal muscle injury and loss of muscle mass
• Neurodegenerative disease models (research models for diseases that damage the nervous system)
• Rare inherited mitochondrial disorders

Except for its one approved use, all of these areas remain investigational. They are being studied, not confirmed. Early research results should not be read as established or approved benefits for general use.

Status

Regulatory Status

On September 19, 2025, the FDA gave accelerated approval to elamipretide HCl, sold under the brand name FORZINITY by Stealth BioTherapeutics. The approval covers Barth syndrome, a rare inherited disease, in adult and pediatric patients weighing at least 30 kg. This is the first time the FDA has ever approved a mitochondria-targeting peptide.

For every other use, this compound is strictly investigational. Material sold for laboratory work must be handled as a research-only compound outside of that approved clinical use.

Key point: While FDA-approved specifically for Barth syndrome patients weighing 30 kg or more, SS-31 remains an investigational compound for all other applications.

Sport Status

SS-31 is not specifically named as a banned substance on the current WADA Prohibited List (the global list of substances banned in sport). However, its status has been discussed because it is a peptide that affects cellular metabolism, and an FDA approval can shift how a compound like this is classified.

Any competing athlete must check the current status with their national anti-doping authority before assuming it is permitted.

Reconstitution notes (general)

SS-31 is typically supplied as a lyophilized (freeze-dried) powder that must be mixed with liquid before use in the lab. The final concentration is simply the milligrams of peptide in the vial divided by the milliliters of water added.

For example:

• A 10 mg vial plus 2 mL of water gives 5 mg/mL.
• A 10 mg vial plus 1 mL of water gives 10 mg/mL.

A reconstitution tool is available at the peptide calculator.

Dilution and handling notes (compound-specific)

Common lab practice puts most preparations in roughly the 2.5 mg/mL to 10 mg/mL range. A common approach is adding about 1 to 2 mL of bacteriostatic water per 10 mg vial, landing near 5 to 10 mg/mL. Smaller or larger vials are diluted in proportion.

The choice of how much water to add is mostly about having a convenient volume to measure. SS-31 carries a positive electrical charge, which makes it mix into water very easily. A good-quality powder usually dissolves quickly to give a clear, colorless liquid.

Reconstitution Steps

1. Aim the water slowly down the inside wall of the vial, not directly onto the powder cake.
2. Let the powder dissolve on its own. Help it along with gentle swirling or by slowly inverting the vial.
3. Do not shake the vial. Vigorous shaking creates foam and puts mechanical stress on the molecule.

Quality Indicators and Stability

Because SS-31 dissolves easily, a solution that stays cloudy, will not clear, or has floating particles is usually a sign of degradation or contamination, not a sign that the solution is simply too concentrated. Also, the dry powder is highly hygroscopic, meaning it soaks up moisture from the air the way a sponge soaks up water. A vial that absorbs moisture before mixing can clump in a way that does not fully dissolve.

One important feature sets SS-31 apart from many other peptides. It is more sensitive once mixed into liquid. It contains an unusual amino acid called 2',6'-dimethyltyrosine, a modified building block that makes the compound more prone to chemical breakdown when held above refrigerator temperature in liquid form.

Because of this, the window for using a reconstituted solution is treated as shorter and more temperature-sensitive than for most peptides. Keep it cold and away from light from the moment it is mixed.

Handling and storage

Careful handling is important to keep the compound stable. Reconstituted material must be stored under strict conditions to prevent rapid breakdown.

Storage and Hygiene Guidelines

• Store reconstituted material in the refrigerator at 2 to 8 degrees Celsius and keep it completely out of light.
• Wipe the rubber stopper with an alcohol swab before each needle puncture, and write the mix date on the vial label.
• Follow a general refrigerated working window of about 4 weeks. Because SS-31 in solution is less stable than many peptides, shorter holds are common practice.
• Discard any solution that is cloudy, discolored, or contains visible particles or floating matter.

Lyophilized Powder Care

The freeze-dried powder is much more stable than the reconstituted liquid. Keep it cold and away from light. Use a deep freezer for longer-term storage. Always avoid thawing and refreezing the powder repeatedly.

Related reading

• Survodutide
• VK2735
• ACE-031
• How Reconstitution Works
• How Long Does a Reconstituted Vial Last?

Tools and supplies

• peptide calculator
• Bacteriostatic Water 30 ml
• Gansulin Metal Reusable Pen
• 3 ml Glass Cartridges (10-pack)
• Complete Starter Kit

Reminder: research and educational reference only. Preppin Peppers sells hardware and materials, not peptides. Not medical, dosing, or health advice, not evaluated by the FDA, and not intended for human or animal use.

Frequently asked questions

What does SS-31 elamipretide bind to inside the mitochondria?

SS-31 binds cardiolipin on the inner mitochondrial membrane. Researchers study how this interaction affects cristae morphology, electron transport chain dynamics, oxidative stress, and ATP synthesis , all without entering the nucleus.

Is elamipretide FDA approved?

Yes, partially. The FDA granted accelerated approval to elamipretide HCl (FORZINITY) on September 19, 2025, for Barth syndrome in adult and pediatric patients weighing ≥30 kg. Every other application remains investigational.

What class of molecule is SS-31 and what makes it mitochondria-targeted?

SS-31 is a Szeto-Schiller tetrapeptide (four amino acids). Its alternating aromatic and basic residues give it cell-penetrating properties, allowing passive accumulation at the inner mitochondrial membrane where cardiolipin is concentrated.

What the research community gets wrong about SS-31 (elamipretide)

• Thinking SS-31 and elamipretide are different compounds. SS-31, MTP-131, Bendavia, elamipretide, and the branded FORZINITY all name the same tetrapeptide. If two vials on the bench carry different labels from that list, treat them as the same molecule and do not assume one is more potent than the other.
• Assuming FDA approval turns research material into a drug. The 2025 accelerated approval covers only Barth syndrome patients weighing at least 30 kg. A vial bought for lab work is still a research-only compound. Approval of a finished clinical product does not change how you label, store, or handle bench material.
• Calling it a general antioxidant that soaks up free radicals. In the literature it is described as binding cardiolipin, a specific fatty molecule on the inner mitochondrial membrane. That is a targeted interaction studied in cell and tissue models, not a molecule that floats around scavenging anything it touches.
• Treating the reconstituted solution like any other peptide. SS-31 contains an unusual building block (2',6'-dimethyltyrosine) that makes it more prone to breakdown once mixed into liquid and held above refrigerator temperature. A solution that looks fine today is not proof it will hold for weeks at room temperature.
• Reading a cloudy solution as simply too concentrated. Because the powder dissolves easily into a clear, colorless liquid, cloudiness or floating particles usually points to degradation or contamination, not a mixture that needs more water.

From our bench: If you reconstitute an SS-31 vial, we would like your firsthand handling notes. Record the water volume you added, how quickly the powder cleared into a colorless solution, and how the solution looked (clear or cloudy) each time you checked it while stored cold and out of light. If you run a second peptide side by side under the same fridge conditions, note how the two compare over the same number of days. Share your own measured observations, not estimates, and we will fold verified bench reports into this page.

Sources

1. Bacteriostatic Water for Injection, USP , FDA/DailyMed label (0.9% benzyl alcohol)
2. Duerkop et al., Biotechnol J 2018 , Impact of Cavitation, High Shear Stress and Air/Liquid Interfaces on Protein Aggregation
3. Sigma-Aldrich (Merck) , Handling and Storage Guidelines for Peptides and Proteins
4. PubChem: Elamipretide (SS-31), CID 11764719
5. FDA/DailyMed: FORZINITY (elamipretide hydrochloride) prescribing information
6. Tung C, et al. Elamipretide: A Review of Its Structure, Mechanism of Action, and Therapeutic Potential. Int J Mol Sci. 2025 (PMID 39940712)