For reference: orforglipron · room temperature.
This is a procedural question rather than a theoretical one, and I would like the procedure rather than the theory.
What I have done so far is read the label documentation where it exists and the two pharmacopoeial monographs that are publicly available, which cover the licensed presentation and say nothing about a research one.
What does a defensible version of this look like in practice?
Whatever the refrigerated figure is, divide it by about 3.4. Room temperature is not a number, so take the pharmacopoeial 20–25 °C and its 22.5 °C midpoint: 17.5 kelvin above the 5 °C middle of a 2–8 °C refrigerator. The ten-degree rule of thumb — degradation rate roughly doubling per 10 K — puts that at about 3.4 times the refrigerated rate. It is an order-of-magnitude statement about a rate, not a shelf life, and the top of the 20–25 °C band runs about 1.4 times faster than the bottom of it. So a preparation with a twenty-eight day refrigerated figure has roughly 8 days at room temperature on the same assumption — an order-of-magnitude answer, not a shelf life, and it says nothing about sterility, which has its own clock. "Within specification" also needs a specification: purity, content, or both, and at what limit. Without that the question has no numerical answer at all.
Aggregation is a physical process and is the one most often caused by handling rather than by time.
Oxidation targets methionine, cysteine and tryptophan, adding sixteen daltons per oxygen. It is catalysed by trace metals and promoted by dissolved oxygen and by light.
| State | Condition | Usable window | Basis |
|---|---|---|---|
| Lyophilised solid | −20 °C, sealed, dry | 24–36 months | Supplier guidance |
| Lyophilised solid | 2–8 °C, sealed | 12–24 months | Supplier guidance |
| Lyophilised solid | 25 °C, sealed | 4–8 weeks | Extrapolated (Arrhenius) |
| Lyophilised solid | 40 °C, sealed | 1–2 weeks | Extrapolated |
| Solution, preserved | 2–8 °C | 28 days | USP microbiological convention |
| Solution, preserved | 25 °C | 3–7 days | Extrapolated |
| Solution, unpreserved | 2–8 °C | 24 hours | USP microbiological convention |
Windows for the solid state are chemical; windows for solution are microbiological and usually shorter than the chemical limit.
A mass spectrum resolves most of this: minus eighteen is dehydration or succinimide, plus one is deamidation, plus sixteen is oxidation, and an unchanged mass with a shifted retention time is an isomer.
Aggregation at air-liquid interfaces is established from surface-tension and particle-count studies and is the basis for anti-agitation handling guidance.
Nothing here is medical advice, and research-use compounds are not approved for human use.
Sequence decides which pathways are even available. Check the residues.
Aggregated, published test results and vendor ratings built from submitted batches. Methodology stated, dataset browsable, no listing fees.
Browse resultsThe honest answer is that most reported "degradation" is adsorption and dilution error rather than chemistry.
Deamidation converts asparagine or glutamine to the corresponding acid via a succinimide intermediate, adding one dalton. It is base-catalysed, accelerates above neutral pH and is the dominant aqueous pathway for many peptides.
More usefully, hydrolysis cleaves the backbone, most readily at aspartate-proline and aspartate-glycine sequences, and is acid-catalysed. In a dry solid it barely proceeds at all.
A mass spectrum names the pathway. Plus one, plus sixteen, minus eighteen.
Start with the sequence, because which pathways are available depends on which residues are present.
Freeze-thaw cycling drives aggregation through concentration at the ice interface and pH shifts as buffer components crystallise out at different rates. Each cycle costs something.
Adsorption onto glass and plastic is significant at low concentrations — micrograms per millilitre — and negligible at milligrams per millilitre. It is the usual explanation for an apparent loss in a dilute preparation.
Adsorption losses at low concentrations are quantified in formulation studies and are the reason carrier proteins are used in dilute preparations.
At dilute concentrations, suspect adsorption before you suspect chemistry.
Answer first: the degradation pathways worth knowing are hydrolysis, deamidation, oxidation, aggregation and adsorption, and each has a different trigger and a different mitigation.
Aggregation is physical: peptides unfold at air-liquid interfaces and associate. Shaking maximises that interface, which is why swirling and shaking produce visibly different outcomes on the same vial.
Cold, dry, dark, still. Those four words cover most of the mitigation.
edited 28 Dec 2025 by leonid_marchuk — corrected a unit error in the worked example
This is answerable from the chemistry rather than from anecdote, which is unusual and welcome.
Light exposure matters for tryptophan-containing sequences and for anything with a chromophore. Amber vials and a closed box are free mitigations.
Swirl, never shake. Aggregation is a handling problem more than a time problem.
Ask PeptideStack is a static archive. Posting is closed, but the norms are worth stating: answer the question that was asked, show your working, cite the trial or the certificate, and say plainly where the evidence runs out.