The quick answer

Step What you use
Add the liquid to the powder A sterile syringe sized for the instructed diluent volume, with an appropriate draw needle for the vial and stopper; use 18G only when suitable
Draw each dose For small subcutaneous (under the skin) doses, a fresh 0.5mL U-100 insulin syringe (31G, 6mm) may be used when specifically directed; otherwise use the syringe and needle specified for the route and volume
Keep it clean An alcohol wipe on every stopper
Finish safely A 0.6L Sharpsafe container

How much water to add

If bacteriostatic water is specified, the volume you add sets the concentration, which sets how many units equal your dose:

Concentration (mg/mL) = peptide amount (mg) divided by water added (mL).

For concentration maths, concentration = vial amount divided by diluent volume. If written instructions specify an amount of X mg from a vial with a concentration of Y mg/mL, the draw volume is X divided by Y. On a U-100 syringe, units = mL x 100. This is a calculation framework, not a dosing recommendation. Use the volume specified for your vial rather than choosing your own, because it changes every amount you draw afterwards. Our guide to reading an insulin syringe has the full mL-to-units table.

A 0.5mL and a 1mL insulin syringe shown for comparing barrel markings
A 0.5mL and a 1mL insulin syringe shown for comparing barrel markings. Use only the syringe type and size specified for the route and volume.

Step by step

  1. Wash your hands and set out the powder vial, bacteriostatic water, draw needle, an alcohol wipe, and your sharps container.
  2. Swab the stopper of both vials and let them air-dry.
  3. Draw the specified volume of bacteriostatic water. Inject an equal volume of air into the water vial first to avoid a vacuum.
  4. Aim the stream of water down the inside wall of the powder vial - not straight onto the powder.
  5. Swirl gently or let it sit until the solution is clear. Do not shake unless the product instructions say to; shaking can foam the solution and may affect product integrity.
  6. Label the vial with the date and concentration, and refrigerate it.
  7. Draw each dose with a fresh sterile syringe specified for that route and volume, swabbing the stopper each time, and dispose of used needles immediately.

Storing it

Refrigerate at 2-8 C unless your written instructions specify otherwise. Do not rely on bacteriostatic water's 28-day multi-dose window as proof of retatrutide stability. The 28-day convention applies after first puncture of the bacteriostatic water vial under aseptic, single-patient handling, does not allow vial sharing, and does not override product-specific limits. Follow the shorter of the written stability limit, product instructions, or local multi-dose handling guidance. Discard any solution that turns cloudy or develops particles. See how long reconstituted peptides last for the detail.

Tip: a vial storage case keeps vials upright, cushioned and organised. It is for physical protection and organisation only. Travel still requires maintaining the specified temperature range with an appropriate insulated cold-pack system and following the product or pharmacy instructions.

Supplies for reconstituting retatrutide

  • 10mL bacteriostatic water vial - use only when specified by written product/pharmacy or research instructions.
  • Draw/transfer syringe - use a syringe sized to the instructed diluent volume, often a smaller syringe for 0.5-3mL additions, with a draw needle gauge suitable for the vial stopper. Avoid 18G unless the written product/pharmacy or research instructions specifically allow it.
  • 0.5mL insulin syringes (31G, 6mm) - may be useful for small subcutaneous volumes when specified; 1mL syringes may be used when specified for volumes within their marked range. Use the needle type, route, and device directed by the written product/pharmacy or research instructions.
  • Alcohol wipes (200-pack) - swab every stopper.
  • 0.6L Sharpsafe container - a locking sharps bin.

We supply the kit, not the medication - browse the supplies range.

When to stop and seek advice

  • The powder will not fully dissolve, or the solution is cloudy or has particles - do not inject it.
  • You are unsure of your concentration, dose volume, or units to draw.
  • Seek medical advice promptly for pus, spreading redness, warmth, swelling, fever, severe pain, or symptoms that persist or worsen over 24 to 72 hours.
  • Persistent vomiting, severe stomach pain (especially radiating to the back), or signs of an allergic reaction - hives, facial or throat swelling, trouble breathing (call 000).
  • You think you drew the wrong amount - do not re-dose to correct it; seek guidance first.

Frequently asked questions

Is retatrutide approved?

No. Retatrutide is investigational and in clinical trials; it is not approved for general use in Australia. Any handling should be under appropriate written product/pharmacy or research direction.

What do I reconstitute retatrutide with?

Use only the diluent specified by written product/pharmacy or research instructions. Where bacteriostatic water is specified, add the stated volume.

How many units do I draw?

It depends entirely on your vial's concentration. Units = dose volume in mL times 100. Get your dose in mL or units for your specific vial; do not reuse a number from another product.

Should I shake the vial?

Do not shake unless the product instructions say to. Swirl gently or let it sit; shaking can foam the solution and may affect product integrity.