How are peptides reconstituted?

What the water changes, and what it does not

Adding more water lowers the concentration and raises the units measured for the same milligram amount. It does not dilute the dose, add anything, or make the material weaker. The only thing being optimised is legibility on the syringe barrel: a standard 100-unit insulin syringe holds 1 mL, so a combination that pushes one measurement past 100 units means drawing twice.

The arithmetic is one line. Units equal the dose in milligrams divided by the concentration in milligrams per millilitre, multiplied by one hundred. Everything else about reconstitution follows from that.

To run it for a specific vial size and volume rather than by hand, use the dosage calculator.

Bacteriostatic versus sterile water

Bacteriostatic water contains 0.9% benzyl alcohol, a preservative that inhibits bacterial growth and permits a vial to be entered more than once. Sterile water has no preservative and is single-use: every entry after the first introduces organisms into a medium that will not suppress them. Where a vial is measured out across several occasions, that preservative is the entire distinction between the two.

Handling

• Both rubber stoppers are swabbed with alcohol and allowed to dry — wiping while wet moves contaminants rather than killing them.
• The water is aimed down the inside wall of the glass rather than onto the powder; a stream striking lyophilised peptide directly can denature it.
• The vial is swirled until dissolved rather than shaken, because peptides are sensitive to the shear forces agitation creates.
• A clear solution is expected; particulates or cloudiness after full dissolution indicate the vial should not be used.
• Reconstituted material is refrigerated. The lyophilised powder is comparatively stable; the solution is not.

These are mechanical steps, and they are the one part of this subject where an instruction is simply an instruction. Nothing here depends on which compound is in the vial.

Where the per-compound pages differ

Vial sizes vary, and the dose points worth tabulating vary with them — a compound with a published trial schedule has meaningful milligram figures to convert, and one without has none. That is why the reference tables live on the individual pages rather than here.