Is there any published stability data for tirzepatide at 2–8 °C?

The specifics, since they change the answer: tirzepatide · 2–8 °C.

I would like to know whether this claim survives contact with evidence.

If the answer is "nobody has tested that", I would like that stated so I can stop looking.

Is this actually true, and what is the evidence?

Probably not at 2–8 °C specifically, because that is not where stability programmes take their readings. Accelerated work is conventionally run at 25 °C and 40 °C, with the refrigerated condition as the control, so 2–8 °C sits between or beyond the published points and what you will find is bracketing rather than a measurement. 2–8 °C is the condition the rule of thumb is anchored to, so it is the baseline rather than a multiplier: everything else in this thread is quoted relative to it. Whatever you find, check what was measured before you use it: a paper reporting purity at 2–8 °C has not measured content, and the two fail at different rates for different reasons.

The honest answer is that most reported "degradation" is adsorption and dilution error rather than chemistry.

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.

Degradation pathway by condition

To be exact about it, 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.

The caveat is that none of these pathways can be seen by looking at a vial, and a clear solution can be substantially degraded.

At dilute concentrations, suspect adsorption before you suspect chemistry.

edited 12 Jun 2026 by Dr_Tomas_Kral — reworded for clarity after a comment