How to
reconstitute.
Reconstitution means dissolving a freeze-dried peptide in bacteriostatic water so it can be measured. Divide the vial in micrograms by the water in millilitres to get the concentration, then divide your dose by that to get the volume. On a U-100 syringe, one unit is 0.01 ml.
Most research peptides ship as a freeze-dried (lyophilized) powder. Reconstitution is the step where you dissolve that powder in bacteriostatic water so it can be dosed accurately. Done carefully it's simple — here's the whole process, plus the math.
What you need
- • The lyophilized peptide vial
- • Bacteriostatic water — sterile water with 0.9% benzyl alcohol, which is what lets one vial be used over weeks. Plain sterile or saline water is single-use only.
- • An alcohol swab and an insulin syringe, U-100 being the usual one
- • A clean, flat surface
The steps
- 1Bring both vials to room temperature. Let the peptide vial and the bacteriostatic water reach room temperature, then swab both rubber stoppers with alcohol.
- 2Draw the water. Draw your chosen volume of bacteriostatic water into the syringe. How much decides the concentration, so pick it before you start rather than after.
- 3Run it down the wall. Insert the needle at an angle and let the water run slowly down the inside wall of the peptide vial. Never squirt it directly onto the powder.
- 4Swirl, never shake. Do not shake. Swirl gently or simply let it stand; the powder dissolves on its own within a minute or two. A clear solution means it is ready, though some peptides stay slightly cloudy.
- 5Label and refrigerate. Write the date and the concentration on the vial, then refrigerate it. An unlabelled vial is a dose you will have to guess at later.
The math (concentration → units)
How much water you add sets the concentration. More water = more dilute = more units to draw per dose (easier to measure small doses). The formulas:
Worked example: a 5 mg vial (5,000 mcg) + 2 ml BAC water = 2,500 mcg/ml. For a 250 mcg dose: 250 ÷ 2,500 = 0.1 ml = 10 units on a U-100 syringe. That vial holds 20 such doses.
| Vial + water | mcg / ml | 250 mcg | 500 mcg | 1000 mcg |
|---|---|---|---|---|
| 5 mg + 1 ml | 5,000 | 5 | 10 | 20 |
| 5 mg + 2 ml | 2,500 | 10 | 20 | 40 |
| 5 mg + 3 ml | 1,667 | 15 | 30 | 60 |
| 10 mg + 1 ml | 10,000 | 2.5 | 5 | 10 |
| 10 mg + 2 ml | 5,000 | 5 | 10 | 20 |
| 10 mg + 3 ml | 3,333 | 7.5 | 15 | 30 |
On a U-40 syringe every figure is 0.4× the number shown — the same volume, a different scale printed on the barrel.
Storage
- • Lyophilized (powder): stable for months to years; cool and dark, fridge or freezer.
- • Reconstituted with BAC water: refrigerate 2–8°C; most peptides stay good ~30 days (some less — check each compound's page).
- • Keep out of light, avoid repeated freeze-thaw, and never leave reconstituted vials at room temperature longer than necessary.
This is general educational information, not medical advice or a recommendation to acquire, possess, or use any compound. Many peptides described on this site are research chemicals not approved for human use in the EU, and some listed compounds are prescription-only. Use sterile technique, never share needles, and consult a licensed physician before starting anything.
How much bacteriostatic water do I add to a peptide vial?
Whatever volume gives a concentration you can measure. More water makes each dose a larger, easier-to-read volume on the syringe; less water makes the vial last longer per millilitre. 2 ml into a 5 mg vial is a common starting point, giving 2500 mcg per ml.
How do I convert a dose in mcg to units on an insulin syringe?
Divide the total micrograms in the vial by the millilitres of water to get mcg per ml. Divide your dose by that number for the volume in ml. Multiply by 100 for units on a U-100 syringe, or by 40 on a U-40.
What is the difference between a U-100 and a U-40 syringe?
The number is units per millilitre. One unit on a U-100 syringe is 0.01 ml; on a U-40 it is 0.025 ml. The same number of units drawn on the wrong syringe is two and a half times the intended volume.
How long does a reconstituted peptide last?
Refrigerated and mixed with bacteriostatic water, commonly around 30 days, though it varies by compound. Plain sterile water has no preservative and is single-use. Storage guidance belongs to the specific compound, not to a general rule.