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Lab guide

How to mix peptides & load a pen.

A simple, careful walk-through for reconstituting a lyophilized peptide vial with bacteriostatic water, then drawing it into a refillable insulin / peptide pen cartridge. For in-vitro research only.

What you'll need

  • Lyophilized peptide vial
  • Bacteriostatic water (0.9% benzyl alcohol)
  • Sterile 3 mL syringe with drawing needle
  • Alcohol swabs
  • Refillable U-100 peptide pen + empty cartridge
  • Pen needle (e.g. 31G × 5 mm)
  • Sharps container

Part 1

Reconstituting the peptide

  1. STEP 01

    Bring vials to room temperature

    Take the peptide and BAC water out of the fridge and let them sit for 10–15 minutes. Cold liquid into a cold vial foams more.

  2. STEP 02

    Swab both stoppers

    Wipe the rubber stopper of the BAC water vial and the peptide vial with a fresh alcohol swab. Let them air-dry.

  3. STEP 03

    Draw the BAC water

    Pull back the syringe plunger to your target volume (commonly 1 mL or 2 mL — check the product page for that peptide), insert into the BAC water vial and draw the exact amount. Tap out any air bubbles.

  4. STEP 04

    Inject down the side of the vial

    Insert the needle into the peptide vial at an angle and slowly trickle the water down the inside wall — not directly onto the powder. This protects the peptide structure.

  5. STEP 05

    Swirl, don't shake

    Gently swirl the vial in your hand until the powder fully dissolves. Never shake — agitation can denature the peptide. Solution should be clear.

  6. STEP 06

    Label and store

    Mark the vial with the date of reconstitution and the resulting concentration (e.g. "5 mg/mL — 12 Jun"). Store refrigerated at 2–8 °C and use within ~28 days.

Quick maths

Concentration = peptide mg ÷ BAC water mL. On a U-100 pen, 1 mL = 100 units. So a 10 mg vial mixed with 2 mL BAC water gives 5 mg/mL — and every 1 unit on the pen delivers 0.05 mg (50 mcg).

Part 2

Loading a refillable peptide pen

  1. STEP 01

    Unscrew the pen

    Twist off the cartridge holder from the pen body. Remove the empty refillable cartridge and lay everything on a clean surface.

  2. STEP 02

    Swab the cartridge stopper

    Wipe the rubber top of the empty cartridge with an alcohol swab and let it dry. The cartridge has rubber at both ends — the top is where you inject.

  3. STEP 03

    Draw reconstituted peptide

    With a fresh syringe, draw your reconstituted peptide from the vial. Most refillable cartridges hold 3 mL — do not overfill.

  4. STEP 04

    Fill the cartridge slowly

    Insert the needle straight down through the rubber top of the cartridge and press the plunger slowly. The lower rubber stopper will slide down as it fills. Keep the needle tip below the liquid line to minimise bubbles.

  5. STEP 05

    Tap out air bubbles

    Hold the cartridge upright (rubber top up) and tap the side so any bubbles rise to the top. If needed, push a tiny amount of liquid back into the syringe to clear trapped air.

  6. STEP 06

    Reassemble the pen

    Drop the filled cartridge back into the cartridge holder (correct orientation for your pen model) and screw it onto the pen body until snug.

  7. STEP 07

    Attach a fresh pen needle

    Swab the cartridge tip, screw on a new pen needle, and remove both caps.

  8. STEP 08

    Prime the pen

    Dial 1–2 units, hold the pen needle-up and press the dose button until a tiny bead appears at the tip. This confirms the pen is loaded and primed.

  9. STEP 09

    Dial your dose

    Dial the units calculated for your protocol (see the product page for unit conversions per peptide). The pen is now ready for use.

For research use only. 🧪

This guide is provided for in-vitro laboratory research only. Nothing on this page is medical advice. Always handle, store and dispose of materials in accordance with your local regulations.

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