How Long Does Epitalon Last? Storage Before and After Mixing
Lyophilised Epitalon keeps for a year or more 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 stability study covers Epitalon in solution, and a 2025 review notes that physico-chemical work on the peptide remains limited, so that window is the general peptide guidance. Its four residues end in an aspartate followed by glycine, a known slow-reacting pair, so a mixed vial is kept cold and dark, and it is never frozen.
Findings
- Epitalon is the tetrapeptide Ala-Glu-Asp-Gly (AEDG), designed from the amino acid composition of a pineal gland extract (Araj et al., Int J Mol Sci, 2025).
- A chemical supplier’s data sheet rates the powder at 2 years at −80 °C and 1 year at −20 °C, sealed away from moisture and light.
- The same sheet gives a stock solution 1 month at −20 °C and 6 months at −80 °C, and lists water solubility of at least 50 mg/mL.
- In a model peptide with the same Asp-Gly pair, the aspartate isomerised in solution above pH 6 (Oliyai and Borchardt, Pharm Res, 1993).
- In the dry state, the same model peptide’s breakdown depended on residual moisture and temperature (Oliyai et al., Pharm Res, 1994).
How long does Epitalon powder last?
The data sheet from MedChemExpress gives Epitalon powder 2 years at −80 °C and 1 year at −20 °C, stored sealed and away from moisture and light. Moisture matters more than usual here. In a lyophilised model peptide carrying the same aspartate and glycine pair, residual moisture and temperature both had a significant effect on how fast it broke down in the solid state (Oliyai et al., 1994). The Epitalon 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 Epitalon last after mixing?
At 2 to 8 °C, dark and accessed only through a swabbed stopper, mixed Epitalon lasts 8 to 12 weeks, with quality fading from around week 6 to 8. Epitalon is named in the general row of how long peptides last after mixing. The Epitalon reconstitution page has the calculator for the 10 mg vial.
What the sequence says about stability
Epitalon dissolves readily in water, and with only four residues it has few places for chemistry to happen. It has no methionine, cysteine, tryptophan or asparagine, the residues behind most oxidation and deamidation. The one point to watch is the aspartate at position 3, followed by glycine. An aspartate can fold back on the next backbone link to form a ring, which reopens as the normal form or as an isomer, iso-aspartate. In model peptides the ring forms more easily when the next residue is small, and glycine is the smallest (Oliyai and Borchardt, 1994). The reaction is slow: in model peptides an aspartate formed the ring 34 times more slowly than an asparagine in the same position (Geiger and Clarke, J Biol Chem, 1987). Epitalon’s glutamate sits at position 2, not at the front of the chain, so the ring closure that turns a leading glutamate into pyroglutamate does not apply. The practical result is the same window as most peptides, kept cold, with a tight stopper and gentle swirling rather than shaking.
What the frozen-solution figures mean
The supplier’s 1 month at −20 °C and 6 months 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 Epitalon last at room temperature?
There is no published figure for Epitalon in solution at room temperature. A mixed vial is taken out of the fridge only for handling, because warmth speeds aspartate isomerisation like every other reaction above.
Can Epitalon be frozen?
The powder can, and the supplier’s longest figure, 2 years, is a freezer 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 Epitalon has degraded?
- Yellowing or any tint. Mixed Epitalon 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.
Isomerisation itself is invisible, since the isomer is just as clear and colourless, which is why the time window applies even to a vial that still looks perfect.
Epitalon storage at a glance
| State | Where | How long |
|---|---|---|
| Powder, sealed | −20 °C / −80 °C, dry, dark | 1 year / 2 years (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 / 6 months (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 Epitalon 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 Epitalon 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 Epitalon last at room temperature?
No published figure exists for Epitalon in solution at room temperature. A mixed vial is kept in the fridge and taken out only for handling.
Can you freeze Epitalon?
Yes as powder: one supplier rates it at 1 year at −20 °C and 2 years at −80 °C. Solution can be frozen once as single-use aliquots, but a working vial should not go through repeated freeze-thaw cycles.
Does Epitalon go bad?
Yes. Its aspartate and glycine pair can slowly isomerise in solution, faster with warmth. Cloudiness, particles, a tint or gel mean it has degraded.
Does Epitalon’s short length make it last longer?
It removes most of the usual weak points, since Epitalon has no methionine, cysteine, tryptophan or asparagine. It does not extend the mixed window, which stays at 8 to 12 weeks in the fridge.
Handling windows: Vistara Labs, October 2026. Sources: Araj SK et al. Overview of Epitalon: highly bioactive pineal tetrapeptide with promising properties. Int J Mol Sci. 2025. PMID 40141333. Oliyai C, Borchardt RT. Chemical pathways of peptide degradation. IV. Pathways, kinetics, and mechanism of degradation of an aspartyl residue in a model hexapeptide. Pharm Res. 1993. PMID 8430066. Oliyai C, Borchardt RT. Chemical pathways of peptide degradation. VI. Effect of the primary sequence on the pathways of degradation of aspartyl residues in model hexapeptides. Pharm Res. 1994. PMID 8058648. Oliyai C et al. Chemical pathways of peptide degradation. VII. Solid state chemical instability of an aspartyl residue in a model hexapeptide. Pharm Res. 1994. PMID 7937533. Geiger T, Clarke S. Deamidation, isomerization, and racemization at asparaginyl and aspartyl residues in peptides. J Biol Chem. 1987. PMID 3805008. MedChemExpress. Epitalon, HY-P1149, product data sheet: sequence, solubility and storage. 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.
