Storage
Two states, two rules. Dry powder is stable if it stays dry and cold. Once water is in the vial, the clock starts.
Lyophilized
−20 °C freezer preferred; a refrigerator is also acceptable. Do not open a cold vial — wait 15–30 minutes so it does not sweat. Avoid freeze–thaw cycling.
Reconstituted
2–8 °C, dark, up to 45 days when mixed with bacteriostatic water. Mixed vials stay in their box. Sterile water (no preservative) is single-use.
Bacteriostatic water
Bacteriostatic water: 20–25 °C. Do not refrigerate the diluent.
Nasal sprays
2–8 °C before and after opening. Up to 45 days after first use. Do not freeze. Return the spray to the fridge after each actuation.
Discard if
- The solution is cloudy, flecked, or will not clear after swirling.
- GHK-Cu loses its blue-green colour or throws a precipitate.
- Glutathione darkens — thiols oxidise even when the molecule’s safety file is otherwise quiet.
- The stopper has been punctured so often it cores or leaks.
- You cannot read the concentration on the label you wrote.