How long do reconstituted peptides last?
There is no universal storage period for every reconstituted peptide. Use the storage conditions and discard date supplied for your specific medication by its manufacturer or dispensing pharmacy.
What the 28-day rule actually covers
The CDC’s injection-safety guidance describes discarding an opened multi-dose vial within 28 days unless its manufacturer specifies another opened-vial date; that date must not exceed the original expiration date. This is not proof that any reconstituted peptide remains stable, sterile, or suitable for use for 28 days.
Do not use a generic web article or a vial-age counter to extend a pharmacy’s discard date. If the label is unclear, ask the dispensing pharmacy for instructions for that exact product.
Keep three dates distinct
- Original expiration date: the date printed for the supplied product.
- Opened or reconstituted date: the date the relevant event actually happened.
- Assigned discard or beyond-use date: the date given in the product-specific instructions.
Use the label’s terminology rather than treating these dates as interchangeable. A number of days since mixing answers an age question; it does not establish a new expiration date.
Create a record for each vial
Give each vial a distinct reference, especially if two have the same treatment name. Record the label’s dates, storage instructions, and lot or batch information where available. Keep the original packaging or label accessible so you can check the record against it.
If you transfer an instruction into a notebook or an app, copy it exactly. Avoid adding a standard refrigeration temperature or storage duration from memory: the specific product instructions are the reference.
What if the storage history is uncertain?
Write down what you know: which vial, when it was opened, the conditions you can account for, and what remains uncertain. Contact your pharmacist about the product before relying on it. A normal-looking vial or a low day count cannot resolve an unknown storage history.
Use inventory tracking for organization
PepShot records vial inventory and days since reconstitution so you can review age and stock alongside your administration history. Those records do not certify potency or sterility and do not replace the labeled discard instructions.
When a vial is replaced, keep its old record distinguishable from the new vial. If you want a record you can bring to an appointment, include the vial reference in the notes column of the printable injection log.