FAQ - peptides & dosing

Peptides are highly potent, so a wrong dose can reduce effectiveness or increase side effects. The calculation matters because tiny volume differences translate into large dose differences. The calculator removes the risk of human arithmetic errors and keeps the maths reproducible.

Bacteriostatic water contains about 0.9 % benzyl alcohol, which inhibits bacterial growth in an opened vial. It matters because it lets you store a reconstituted vial for several uses. Never use tap water or boiled water for injections.

Choose a practical amount: not too little (dissolves poorly, stings) and not too much (injection volume too large). For standard vials (5-10 mg), 2-3 ml is a proven default. More water lowers the concentration, so you draw up a larger volume for the same dose.

Yes. More water lowers the concentration, so you draw up a larger volume for the same dose; less water does the opposite. Adjust the calculation accordingly - the calculator does this automatically once you change the water volume.

A peptide calculator works out the exact liquid volume you need to draw up to inject a given dose. Because peptides ship as a powder (lyophilisate), you first mix them with bacteriostatic water (BAC). The calculator removes the guesswork from converting milligrams of powder into millilitres on the syringe.

Volume to draw up (ml) = (target dose ÷ vial strength) × BAC water added. Example: 250 mcg target, 5 mg (5000 mcg) vial, 2 ml water → (250 ÷ 5000) × 2 = 0.1 ml. On a U100 syringe, 0.1 ml = 10 units (IU). This formula always converts your target dose into a volume you can read on the syringe.

What matters is the syringe's scale (U-100 or U-40), not its size. On the common U-100 insulin syringe: 100 units (IU) = 1 ml. So 50 IU = 0.5 ml, 20 IU = 0.2 ml, 10 IU = 0.1 ml.

Don't confuse the scale with the barrel size: U-100 syringes come in different capacities. The most common for peptides is the "50-unit" (0.5 ml) - it holds at most 50 IU = 0.5 ml. A full millilitre does not fit; 1 ml equals 100 IU, i.e. a full 1-ml/100-unit syringe. Common U-100 sizes:

• 0.3 ml = 30 IU (U-100)
• 0.5 ml = 50 IU (U-100) - the most common
• 1.0 ml = 100 IU (U-100)

Less common is the U-40 scale (40 IU = 1 ml, i.e. 10 IU = 0.25 ml), typical for some veterinary insulins. Always read the "U-100" or "U-40" marking on the syringe and convert accordingly. Our injection calculator gives you the right volume.

BAC water (bacteriostatic water) contains 0.9 % benzyl alcohol as a preservative that inhibits bacterial growth, allowing multiple withdrawals from the same vial for up to 28 days after first puncture. Sterile water, by contrast, contains no preservative and must be discarded after a single use - it is not suitable for multi-dose applications.

The benzyl alcohol in BAC water is bacteriostatic (growth-inhibiting), not bactericidal (killing). Strict aseptic technique is therefore essential: always swab the rubber stopper with an alcohol wipe before each puncture, use a sterile needle and syringe, and store the vial refrigerated (2-8 °C) after opening. Cloudiness, particles, or discoloration are warning signs - discard the vial immediately.

A common misconception: BAC water does not extend the shelf life of the peptide itself; it only protects against microbial contamination during repeated access. The peptide's chemical stability depends on factors like temperature, light, and pH. See our FAQ on storing reconstituted peptides for more details.

Most reconstitution mistakes are easy to avoid if you work cleanly, slowly and with the right water. The five most important ones:

1. Shaking instead of swirling: Vigorous shaking can damage the peptide structure and cause foaming - swirl the vial gently instead.
2. Wrong solvent: Tap water or saline instead of BAC water. Only bacteriostatic water inhibits bacterial growth and allows multi-day storage.
3. Adding water too fast: Injecting BAC water directly onto the powder causes foaming or uneven dissolution. Let the water run slowly down the vial wall.
4. Inaccurate water volume: The wrong amount of BAC water changes the concentration and therefore your dose.
5. Poor hygiene: Disinfect the vial septum and injection site with alcohol before each use.

For a complete walkthrough, see our step-by-step reconstitution guide.

Short answer: A peptide that has already been reconstituted (mixed) with BAC water belongs in the refrigerator at 2-8 °C, not in the freezer.

Freezing forms ice crystals that mechanically disrupt the sensitive amino acid chain; during thawing, additional concentration gradients and pH shifts further distort the structure. Each freeze-thaw cycle reduces biological activity cumulatively, often by 20-50 % in a single cycle, so repeatedly thawing and re-freezing the same vial must be strictly avoided.

Only the unreconstituted lyophilisate (powder) should be frozen, ideally at -20 °C or colder, kept dry, dark and in a sealed vial with desiccant. If you need a vial over several weeks, split the powder into smaller vials before reconstitution so you only dissolve a fresh dose when needed.

A detailed step-by-step guide is here.