How Long Does SS-31 Last? Storage Before and After Mixing
Lyophilised SS-31 (elamipretide) keeps for years sealed, dry and frozen; once mixed with bacteriostatic water it lasts 8 to 12 weeks at 2 to 8 °C under Vistara Labs’ handling guidance, with quality slowly fading from around week 6 to 8. No published study gives a figure for SS-31 in solution, although its developer’s review describes it as very stable in solution, so that window is the general peptide guidance. Its four residues carry none of the usual weak points, and its dimethyltyrosine is the one part that reacts with oxidants, so a mixed vial is kept dark and cold, and it is never frozen.
Findings
- SS-31 is the tetrapeptide D-Arg-Dmt-Lys-Phe-NH2, where Dmt is 2′,6′-dimethyltyrosine (MedChemExpress data sheet; Szeto, Br J Pharmacol, 2014).
- A chemical supplier rates the powder at 3 years at −20 °C from the date of receipt.
- The same supplier gives a stock solution 1 month at −20 °C and 1 year at −80 °C.
- Its developer’s review calls SS-31 “very stable in solution” and credits the D-arginine and the amidated end with greatly enhanced stability against peptidase degradation (Szeto, 2014). No figure in weeks is given.
- It has no methionine, cysteine, tryptophan, asparagine or aspartate, the residues behind most oxidation, deamidation and isomerisation.
How long does SS-31 powder last?
Selleck Chemicals gives elamipretide powder 3 years at −20 °C, counted from the date of receipt. MedChemExpress refers buyers to the storage conditions on each batch’s certificate of analysis rather than printing a single figure. Moisture is the main enemy of a freeze-dried cake: it lets the same reactions that happen in solution start in the solid, so the cake is kept sealed and dry. The SS-31 10 mg vial is kept capped and boxed, in the fridge for near-term work or the freezer for longer holds, and a cold vial is brought to room temperature before opening so that condensation does not form on the powder.
How long does SS-31 last after mixing?
At 2 to 8 °C, dark and accessed only through a swabbed stopper, mixed SS-31 lasts 8 to 12 weeks, with quality fading from around week 6 to 8. SS-31 is named in the general row of how long peptides last after mixing. The SS-31 reconstitution page has the calculator for the 10 mg vial.
What the structure says about stability
SS-31 is highly water-soluble; MedChemExpress lists 25 mg/mL in water with ultrasound. Its structure is unusual. The first residue is D-arginine, the mirror-image form, and the end is capped as an amide, two changes its developer credits with greatly enhanced stability against peptidase enzymes (Szeto, 2014). Enzyme resistance matters in tissue, not in a sterile vial, but the chemistry is also favourable: the four residues include no methionine or cysteine to oxidise, no asparagine to deamidate and no aspartate to isomerise. The one reactive site is the dimethyltyrosine. That residue is what lets SS-31 scavenge oxidants in laboratory studies (Zhao et al., J Biol Chem, 2004). It is a modified tyrosine, and tyrosine is among the residues most open to oxidation, which light can drive (Li et al., Biotechnol Bioeng, 1995). The practical result is the same window as most peptides, with care over light, a tight stopper and gentle swirling rather than shaking.
What the frozen-solution figures mean
The supplier’s 1 month at −20 °C and 1 year at −80 °C apply to stock solutions frozen once and kept sealed, a laboratory practice for single-use aliquots. They are not a reason to freeze a working vial that will be thawed and opened again.
How long does SS-31 last at room temperature?
There is no published figure for SS-31 in solution at room temperature. “Very stable in solution” is a description, not a time limit. A mixed vial is taken out of the fridge only for handling, because warmth speeds every chemical reaction in solution.
Can SS-31 be frozen?
The powder can, and the supplier’s 3 year figure is a −20 °C figure. Single-use aliquots of solution can be frozen once. A working vial should not be frozen and thawed repeatedly, since freeze-thaw cycles aggregate peptides in solution.
How can you tell mixed SS-31 has degraded?
- Yellowing or any tint. Mixed SS-31 should be clear and colourless.
- Cloudiness that does not clear within 10 to 15 minutes of mixing, or that appears later.
- Particles or sediment.
- Gel or thickening.
Slow oxidation is invisible, which is why the time window applies even to a vial that still looks perfect.
SS-31 storage at a glance
| State | Where | How long |
|---|---|---|
| Powder, sealed | −20 °C, dry | 3 years from receipt (supplier data sheet) |
| Powder, sealed | 2 to 8 °C, dry, dark | No supplier figure found; near-term holds |
| Mixed with bacteriostatic water | 2 to 8 °C, dark | 8 to 12 weeks, fading from week 6 to 8 (store guidance) |
| Solution aliquots, frozen once | −20 °C / −80 °C | 1 month / 1 year (supplier data sheet) |
| Mixed, room temperature | Handling only | No published figure |
Certificates of analysis are on the lab reports page, and every order ships from within Canada by Canada Post Xpresspost.
Vistara Labs supplies SS-31 as a laboratory research material. The windows on this page describe how long the peptide stays in good condition.
Frequently asked questions
How long does SS-31 last in the fridge after mixing?
Under Vistara Labs’ handling guidance, 8 to 12 weeks at 2 to 8 °C in the dark, with quality fading from around week 6 to 8.
How long does SS-31 last at room temperature?
No published figure exists for SS-31 in solution at room temperature. A mixed vial is kept in the fridge and taken out only for handling.
Can you freeze SS-31?
Yes as powder: one supplier rates it at 3 years at −20 °C. Solution can be frozen once as single-use aliquots, but a working vial should not go through repeated freeze-thaw cycles.
Does SS-31 go bad?
Yes, slowly. Its dimethyltyrosine can oxidise in solution, faster with warmth and light. Cloudiness, particles, a tint or gel mean it has degraded.
Why is SS-31 described as very stable in solution?
It has none of the residues that usually break down first, and its D-arginine and amide cap resist enzymes. That describes the molecule; it does not extend the 8 to 12 week mixed window.
Handling windows: Vistara Labs, October 2026. Sources: Szeto HH. First-in-class cardiolipin-protective compound [title shortened]. Br J Pharmacol. 2014. PMID 24117165. Zhao K et al. Cell-permeable peptide antioxidants targeted to inner mitochondrial membrane inhibit mitochondrial swelling, oxidative cell death, and reperfusion injury. J Biol Chem. 2004. PMID 15178689. Li S, Schöneich C, Borchardt RT. Chemical instability of protein pharmaceuticals: mechanisms of oxidation and strategies for stabilization. Biotechnol Bioeng. 1995. PMID 18623513. Selleck Chemicals. Elamipretide (SS-31), S9803, product page: storage and stock solutions. Data sheet. MedChemExpress. Elamipretide, HY-P0125, product data sheet: sequence and solubility. PDF.
More on this: How Long Do Peptides Last After Mixing?
All products supplied by Vistara Labs are intended for laboratory research use only. They are not drugs, are not approved for human or veterinary use, and are not intended to diagnose, treat, cure or prevent any condition. Nothing on this page constitutes medical advice or guidance for use in humans.
