[PSA] excursion is not what most of this community thinks it is
Explainer, as requested in the last thread: excursion is not what most of this community thinks it is. A transit temperature logger records a distribution, and time above a threshold matters as much as peak temperature. That is the argument for logging rather than guessing. Gel packs are designed for a duty cycle. A…
Lyophilisation removes the water that drives most degradation pathways. That is why the dry cake is comparatively robust and the reconstituted solution is not.
Once in solution, the relevant risks are hydrolysis, aggregation and, for some sequences, oxidation. Refrigeration slows all three; freezing a solution introduces a separate risk at the ice interface.
a summer lane and a winter lane are different lanes
write the reconstitution date on the vial
a summer lane and a winter lane are different lanes
This is the distinction that resolves most threads here — powder and solution are different problems.
Gel pack fully liquid on arrival, powder tested 97.6% against a claimed 97.0% afterwards. The pack had done its job for as long as it was designed to.