Glutathione Reconstitution Calculator

Your calculator treats all peptides as simple powders. However, GSH is the biologically active form and is easily oxidized to GSSG by air, light, or elevated pH. GSH is soluble in water, giving a clear, colourless solution, while GSSG is more stable but less active. A yellow tint or cloudiness suggests partial oxidation to GSSG, which still contributes to the total mass but has different biological activity. Your calculator will correctly compute concentration and units based on the mass you enter, but it cannot warn you about this redox chemistry. If oxidation is a concern, consider using a buffer with a pH between 5.0 and 8.0, as described in extended‑storage patents.

The calculator assumes full potency for the entire content of the vial. For glutathione, the compound is indeed “unstable in solutions,” and many suppliers advise that “freshly prepared is recommended”. In lyophilised form, glutathione can be stable for up to 36 months, but once reconstituted, it must be stored at −20 °C and used within one to three months to prevent loss of potency. If you plan to use a single vial over several days or weeks, you should aliquot the solution immediately after reconstitution and freeze the aliquots at −20 °C. The calculator’s “Doses per vial” display is a mathematical maximum, not a guarantee of full activity for that number of doses.

For a 1500 mg vial, a protocol that uses 5 mL of BAC water gives a concentration of 300 mg/mL, which is still very high but has been used with daily doses of 100–200 mg (approx. 33–67 units on a U‑100 syringe). Your calculator will allow this combination. If you use only 1 mL of water, the calculator will still show the resulting concentration, but you must verify that such a concentrated solution (1500 mg/mL) is physically manageable and does not precipitate. Glutathione has a solubility of about 41 mg/mL in water. A 1500 mg/mL concentration would far exceed this and would likely be impossible to achieve. Your calculator does not check solubility limits – you must ensure that the concentration you derive does not exceed the peptide’s known solubility.

Bacteriostatic water typically has a pH around 5.0‑5.5, which falls within the acceptable range for GSH stability. However, some research-grade glutathione preparations include sodium bicarbonate to neutralise the solution, raising the pH closer to 7.4, which may further enhance stability. The calculator is solvent‑agnostic; it only uses the volume you enter. If you wish to adjust the pH, you can do so before adding the BAC water to the vial. However, be aware that adding sodium bicarbonate will change the volume and concentration, so you must account for the added liquid.

Mannitol is a bulking agent, often included in lyophilised glutathione formulations to improve the physical structure of the freeze‑dried cake and to protect the peptide during lyophilisation. The total mass of the solid in the vial is the sum of the active peptide plus the mannitol. The manufacturer will state the active peptide mass (e.g., “1500 mg glutathione”) separately from the total fill weight. You should only enter the active peptide mass into your calculator. Adding extra mass from mannitol would incorrectly increase the calculated concentration and dose. If the label does not specify the active content, contact the supplier before using the calculator.