My cagrilintide vial sat at room temperature for twenty-eight days — is testing worth it before use?

What I have: cagrilintide · room temperature · twenty-eight days.

I would rather over-plan the first cycle and simplify later.

I am prepared to do the work if someone can tell me which work matters.

How do I make this decision on evidence rather than on feel?

Twenty-eight days at room temperature is about 94 refrigerated days of equivalent exposure. 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. At 94 equivalent days a test is more likely to reassure you than to tell you something, which is a legitimate reason to run it and a poor reason to expect a finding. Either way, record the twenty-eight days and the temperature now, while you still know them; an excursion you did not write down is an excursion you cannot interpret later.

Answer first: for a lyophilised solid the cold chain matters far less than people believe, and for a solution it matters far more than they act as though it does.

A single phase-change pack in a thin-walled box holds below ten degrees for roughly one to two days at twenty-five degrees ambient, and under a day at thirty-five. On a nine-to-fourteen-day lane the material is at ambient for most of the journey whatever was packed with it.

On the detail: arrhenius behaviour means the degradation rate roughly doubles per ten degrees. A week at thirty degrees is therefore a meaningful exposure for a solution and an immaterial one for a dry solid.

The caveat is that a warm transit is survivable for a solid and materially different for a solution.

Buy a logger if you actually want to know. Everything else is inference.

edited 13 Feb 2025 by lane_transit — tightened the wording; no substantive change

The relevant physics is latent heat: a phase-change pack holds temperature only while it is changing phase, and once it has melted it is a warm mass.

A pack that arrived hard tells you about the last day of transit only, since it will have melted and, if the ambient dropped, partially refrozen.

Worth being precise here: a single-use temperature logger costs a few pounds, records the whole journey and converts an argument into a record. If the history matters, this is the answer.

A cold pack tells you nothing about the eleven days before the last one.

A liquefied pack is expected. It is not evidence of a problem.

edited 13 Feb 2025 by seven_day_half — updated for the 2026 guidance change

Start with the physical state, because it changes the answer completely and is the first thing to establish.

Asking a supplier to hold a shipment during a heatwave is reasonable and the better ones agree; the cost is a week and the benefit is a shorter warm exposure for anything in solution.

To be exact about it, anything shipped in solution is a different risk category, because hydrolysis and deamidation proceed in the aqueous phase and are strongly temperature-dependent.

Reconstituted material has a genuine cold-chain requirement and it starts the moment water is added.

Solutions are a different question and deserve the worry the solids get.