How to Reconstitute Peptides

What reconstitution means

Many peptides come as a dry powder in a sealed glass vial. The powder has been freeze dried, which is also called lyophilized.

To reconstitute means to add a liquid so the powder turns back into a solution. The liquid is called the diluent, and it is often bacteriostatic water or sterile water.

Once the powder dissolves, the vial holds a liquid with a set concentration. That is the amount of powder in each mL.

What you need

• The vial of powder, with its label.
• The liquid named on the product label.
• New, sterile syringes and needles, still sealed.
• Alcohol swabs.
• A clean, flat surface with good light.
• A pen and a sticker or label for the vial.
• A sharps container for used needles.

Check the label first

Before you start, read the product's own label or insert. Look for three things:

1. Which liquid to use. Some products need bacteriostatic water. Some need plain sterile water. Some need something else.
2. How much liquid to add. The label or your prescriber sets this. This site does not.
3. How to store it after mixing. Look for a storage line and a time limit.

The bacteriostatic water label backs this up: it says to check the drug maker's instructions for which liquid to use and how much. It also warns that some drugs do not mix well with benzyl alcohol, its preservative, and says to ask a pharmacist when you can.

If the label is missing or unclear, stop and ask a pharmacist.

How to reconstitute peptides, step by step

Step 1: Clean your hands and your space

Wash your hands well. Wipe down a clean, flat surface. Lay out what you need so nothing touches a dirty spot.

Step 2: Check the vial

Read the label and the expiry date. Look for cracks or a broken seal. The powder should look like what the label describes. If anything looks wrong, do not use it.

Step 3: Let a cold vial reach room temperature

If the vial was kept cold, a lab handling guide says to let the closed vial reach room temperature before opening it, so water from the air does not get in (Bachem). Follow your own product label first.

Step 4: Wipe the rubber tops

Take the plastic caps off. Wipe the rubber top of each vial with a fresh alcohol swab. Let it dry, since this is a common part of clean technique. CDC says to use clean, aseptic technique every time you enter a vial.

Step 5: Use a new needle and syringe

CDC says to use a new, sterile needle and syringe each time you enter a vial. Never leave a needle in the rubber top between uses.

Step 6: Draw up the liquid

Draw the amount of liquid your label calls for from the water vial. Check the mark on the syringe twice.

Step 7: Add the liquid to the powder vial

Put the needle into the powder vial and add the liquid. The product's own instructions decide how to add it and how to mix it.

Step 8: Let it dissolve

Let the vial sit until the powder dissolves. If the product's instructions say how to mix it, follow them. If they do not, ask a pharmacist.

Step 9: Check that it is clear

Hold the vial up to the light. The bacteriostatic water label says to check a mixed drug for clarity. It should have no specks, no cloudiness and no odd color. If it does, do not use it, and ask a pharmacist.

Step 10: Label and date the vial

Write the date you mixed it, the liquid you used, how much you added and the concentration. Date the water vial too, on the day you first open it. Infection control researchers who checked a hospital's opened vials found many with no date at all, and they listed dating as a fix (Mattner and Gastmeier, 2004).

Step 11: Store it as the label says

Store the mixed vial the way the product label says. The bacteriostatic water label says not to store a mixed drug unless the drug maker allows it. See how to store peptides for more.

Work out the concentration

Concentration is the mass in the vial divided by the liquid you added.

Say the vial label reads 10 mg and you added 2 mL. 10 divided by 2 is 5. So the solution is 5 mg/mL. That is the same as 5,000 mcg/mL.

Use the peptide reconstitution calculator to do this with your own numbers, or see many results at once in the peptide reconstitution chart. Both show concentration only, never a dose.

Label the vial

A clear label stops mix ups later. Copy this onto a sticker:

• Mixed on: the date
• Liquid used: for example, bacteriostatic water
• Liquid added: in mL
• Mass in vial: in mg, from the label
• Concentration: in mg/mL
• Water vial opened on: the date
• Water vial discard by: 28 days after it was opened, unless its maker says otherwise

That last line comes from CDC guidance for opened multi-dose vials and matches USP chapter 797, but it is not printed on the water label itself. Read more in how long bacteriostatic water lasts.

Stop if you see this

Do not use the vial, and ask a pharmacist, if:

• The liquid is cloudy, or has specks or a color change.
• The powder will not dissolve.
• The rubber top is cracked, loose or pushed in.
• The glass is cracked or chipped.
• The label is missing, or you cannot read it.
• The vial is past its expiry date.

Common mistakes

• Skipping the label. The label sets the liquid, the amount and the storage.
• Using the wrong liquid. Bacteriostatic water and sterile water are not the same. See bacteriostatic water vs sterile water.
• Reusing a needle. CDC says a new needle and syringe every time.
• Leaving a needle in the top. CDC says never to do this.
• Not writing anything down. You will forget the date and the concentration.
• Getting the math wrong. Divide the mass by the liquid. Check it with the calculator.

Printable checklist

Print this page and tick each line as you go.

1. Read the product label: liquid, amount, storage.
2. Wash hands and clean the surface.
3. Check the vial, the seal and the expiry date.
4. Let a cold vial reach room temperature, if your label allows.
5. Wipe both rubber tops with alcohol and let them dry.
6. Use a new, sterile needle and syringe.
7. Add the liquid to the powder vial.
8. Let it dissolve, mixing only as the product's instructions say.
9. Check it is clear, with no specks.
10. Label it: date, liquid, amount and concentration.
11. Store it as the label says.