Why it arrives as a powder
Most peptides arrive as a small amount of white powder sealed in a glass vial, not as a liquid. The powder is the product. Nothing has gone wrong.
Peptides are fragile in water. Dissolved, they degrade — faster when warm, faster still over weeks. So they are freeze-dried: frozen, then the water is drawn off under vacuum, leaving a dry solid. You will see this called lyophilised, which is the same thing. Dry, cold and dark, the molecule keeps far longer than it would in solution.
That solid is often a thin film or a small puck rather than a visible pile, because the amount involved is genuinely tiny. A vial that reads 10 mg contains ten thousandths of a gram. Seeing almost nothing in the vial is normal and is not evidence of anything either way.
What reconstitution names
Reconstitution is simply the step of adding a sterile liquid back to that powder so it becomes a solution again. That is all the word means. It is not a technique, a skill, or a protocol — it names one action.
The liquid is usually bacteriostatic water: sterile water with a small amount of a preservative added, which is what allows a vial to be entered more than once without the contents supporting bacterial growth. Plain sterile water has no preservative, which is why the two are not interchangeable for a container you intend to use more than once.
How much liquid, whether a particular product should be reconstituted at all, and what to do with it afterwards are not questions this site answers. They come from the product's own labelling, a dispensing pharmacy, or a clinician. What we can explain is the arithmetic that follows once those numbers exist — which is the next step.