How long does a reconstituted vial last?

For most peptides in solution, refrigerated stability after reconstitution with bacteriostatic water is on the order of 30 days. Some peptides are more stable and can be refrigerated for several months; others are less stable and require use within days. The controlling factors are the peptide's specific chemistry (susceptibility to hydrolysis, oxidation, aggregation), the diluent (bacteriostatic water with preservative extends usable life vs preservative-free saline), and the storage conditions (refrigerator vs freezer vs room temperature).

Some specific patterns worth knowing: Semaglutide and tirzepatide pre-filled pens typically have 30–56 day post-first-use windows depending on the specific product label. BPC-157 reconstituted with bacteriostatic water is commonly considered stable for about 30 days refrigerated. Glutathione is more oxidatively sensitive and typically requires more careful handling. NAD+ solutions have specific stability profiles that depend on the buffer system used.

The safe default when specific stability data is not available: assume 30 days refrigerated in bacteriostatic water for typical research-supply peptides, discard sooner if any visible change occurs (cloudiness, discoloration, particulate), and follow the supplier's beyond-use date when one is provided. For long-term storage of reconstituted material, aliquoting into single-use portions and freezing minimises the freeze-thaw exposure that reduces potency.