Accepted answer
Nobody has published a cycle count, and at 8 mg/mL the concentration tells you what a wrong guess costs: a 0.1 mL aliquot holds 0.8 mg and every microlitre is 8 µg. Damage from freezing is not gradual attrition — it is concentrated at the phase transitions, where ice excludes solute and the unfrozen fraction climbs well above 8 mg/mL for as long as the transition lasts. Two slow cycles can therefore do more than four fast ones, which is why a cycle count is the wrong unit in the first place. The way to make the number one is to make it one: split at reconstitution into single-draw aliquots, label each with 8 mg/mL and the date, and never thaw a container you will refreeze.
Start with how many cycles are actually planned, because one or two are immaterial and ten are not.
Thaw slowly at room temperature or in the refrigerator rather than in warm water. Rapid warming creates local thermal and concentration gradients that promote aggregation.
Reported and extrapolated stability by condition
| 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 dry lyophilised powder is much less affected by a temperature cycle because there is no liquid phase for anything to concentrate into. Condensation on a cold vial opened warm is the real risk there.
Aliquoting to eliminate repeated cycles is standard laboratory practice for exactly this reason.
The number of tolerable cycles is sequence- and formulation-dependent and no general number is honest.
Count cycles, not degrees. The cycle is the damaging event.
7Confirming that opening a cold vial in a humid room is a genuinely bad idea. – lipid_panel_q 6 months ago add a comment