PE-22-28 Reconstitution Calculator

PE-22-28 is a highly amphipathic peptide containing a hydrophobic tryptophan residue and a strongly basic C-terminal arginine, which limits its water solubility. When reconstituting a 10 mg vial, a solubility ceiling of 2 mg/mL means you must use at least 5 mL of BAC water (10 mg / 2 mg/mL). Using the calculator’s default small BAC volumes (e.g., 1 mL) would attempt to create a 10 mg/mL solution, exceeding the peptide’s solubility limit by a factor of five. The result will be a cloudy, partially dissolved solution that leads to unpredictable dosing. Always ensure the final concentration does not exceed 2 mg/mL, even if the calculator marks a smaller volume as “Best” for unit roundness.

No, and this may be misleading. PE-22-28 was developed from spadin degradation products and blocks the TREK‑1 potassium channel with an IC₅₀ of just 0.12 nM, making it several hundred times more potent than its parent molecule spadin. In living animal studies, the duration of action of PE‑22‑28 is about 23 hours, compared to only 7 hours for spadin. A single daily dose of as little as 3 μg/kg (intraperitoneal) is already sufficient to induce antidepressant‑like effects in mice. If you simply enter a higher mg value into the calculator expecting a proportionally stronger effect, you may surpass the optimal therapeutic window and produce no additional benefit—or even a reduced effect—due to the unusually high potency and prolonged duration of this peptide.

The peptide is most commonly supplied as a trifluoroacetate (TFA) or acetate salt. For a typical acetate salt formulation, the peptide may dissolve more readily in acidic conditions. If you simply add BAC water and the solution remains cloudy (exceeding the 2 mg/mL limit), you can warm the tube to 37 °C and shake it in an ultrasonic bath to improve dissolution without compromising the integrity of the lyophilised material. Your calculator cannot warn you about this need for additional physical agitation, which is specific to acetate formulations of this heptapeptide.

The specialised handling note for PE‑22‑28 instructs researchers to allow both the peptide and chosen solvent to reach ambient laboratory temperature before reconstitution to help maintain structural integrity during dissolution. If you follow the calculator’s generic protocol and immediately add cold BAC water directly from the refrigerator, the sudden temperature shock can cause aggregation of the peptide, leading to an incompletely dissolved solution and inaccurate syringe draws, even if the final concentration is mathematically correct. The peptide’s sequence contains a tryptophan residue that is particularly sensitive to aggregation when combined with a hydrophobic core region, making this pre‑warming step essential.

The peptide’s design ensures enhanced stability in biological fluids, but after reconstitution in BAC water, the solution can be stored at 2‑8 °C for up to 28 days under sterile conditions before significant degradation begins, as per the manufacturer’s data sheet for this peptide. The calculator’s mathematical “Doses per vial” number is a maximum theoretical count based purely on mass. If you have a 10 mg vial and plan to use it for more than 4 weeks (e.g., 30 daily doses), the later injections may contain degraded material. The 28‑day stability window is a real chemical constraint that the calculator does not display. Always align your usage plan with the 28‑day shelf life to ensure consistent potency for the entire study duration.