Posting this because the summary going around does not say what the paper says, and the difference matters for how people here are using it.
Freezing is the one to avoid, and freeze-thaw more so. Ice-crystal formation and the concentration changes at the phase boundary drive aggregation, and aggregated peptide does not recover on thawing. A vial that has been frozen and thawed is not rescued by returning it to the fridge.
Where I think it is weakest: the subgroup findings are the part I trust least — with enough subgroups something is always significant, and these were not all pre-registered.
The bit I cannot resolve on my own is what a temperature excursion actually does, and what distinguishes an unopened vial from one already in use. Tell me what I have not thought of.
Figures above are from the primary publication rather than the press summary. If a number here disagrees with one you have, post yours and we will work out which of us is reading a secondary source.
PeptideChemSF said:Freezing is the one to avoid, and freeze-thaw more so.
Storage question about storage and cold: my pen was left out of the fridge for 8 hours. Is it still good?
Per the manufacturer, both Ozempic and Wegovy pens can be stored at room temp (up to 86°F) for up to 28 days after first use. So yes, it should be fine as long as it wasn't exposed to extreme heat.
PeptideChemSF said:Freezing is the one to avoid, and freeze-thaw more so.
Pushing back on PeptideChemSF here. The distinction that matters is unopened versus in use. Unopened vials are stable refrigerated for their labelled shelf life and tolerate a limited excursion to room temperature. Once reconstituted, the clock is much shorter and is set by the preservative rather than by the peptide — bacteriostatic water's benzyl alcohol is what buys you multiple draws over weeks. Sterile water has no preservative and turns a multi-dose vial into a single-use one.
Sigma-Aldrich — Research-Grade Standards
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Shop Reference StandardsNurseKim_ATL said:The distinction that matters is unopened versus in use.
Storage best practices for compounded storage and cold:
- Unreconstituted lyophilized powder: refrigerate (36-46°F), good for 12+ months
- Reconstituted vials: refrigerate, use within 28 days
- Pre-filled pens: refrigerate until first use, then room temp OK for 28 days
- Never freeze reconstituted peptides — ice crystals damage the protein
- Protect from light — store in original box or wrap in foil
When in doubt, refrigerate. Temperature abuse is the #1 cause of reduced potency in compounded peptides.
amsterdam_pete said:Storage question about storage and cold: my pen was left out of the fridge for 8 hours.
Second this. Posting only so the count is not one.