Reconstitution

Returning a lyophilised solid to solution by adding a measured volume of diluent — the step that fixes the solution's concentration and restarts the stability clock.

Reconstitution is the reversal of lyophilisation: a measured volume of diluent is added to the dry cake, dissolving it back into solution. Two things are decided at that moment. The ratio of compound mass to diluent volume fixes the solution's concentration, and the return of water restarts the degradation chemistry that drying had suspended.

Concentration is arithmetic, not measurement: the vial's stated content divided by the volume added. Every downstream calculation inherits that figure, along with its caveats — the label mass is gross powder, and where net peptide content was not measured, the true concentration of peptide is somewhat lower than the nominal one. The site's calculator does this arithmetic in both directions and sets out the common errors.

Stability in solution is a different regime from stability as a solid. Hydrolysis and aggregation resume with mobility, temperature matters more, and the diluent's preservative determines the microbiological holding time of an opened vial. The mechanisms, and what they imply for how long a solution remains what its label says, are the subject of the stability guide rather than this entry.

For research purposes only. Not for human consumption, diagnosis, treatment, or prevention of any condition. Nothing on this page is medical advice.