Filling a cartridge and using the pen – step by step

1. Step 1

   Get your supplies ready

   • Reconstituted vial (clear, no flakes)
   • Empty, sterile 3 mL cartridge – never reuse
   • Sterile disposable syringe with a needle for drawing up, plus a second thin needle for venting
   • Alcohol swabs, new pen needles, sharps bin
   • Clean, disinfected work surface; wash your hands thoroughly

2. Step 2

   Disinfect the stoppers and equalise the pressure

   Wipe the rubber stoppers of the vial and cartridge with alcohol and let them dry. Draw as much air into the syringe as the amount of solution you want to remove, and inject it into the upright vial. This prevents a vacuum – otherwise the solution is hard to draw up and bubbles form.

3. Step 3

   Draw up the solution

   Turn the vial upside down; the needle tip stays in the liquid. Pull the plunger out slowly – a little more than needed, so that you can push out air afterwards.

4. Step 4

   Remove air bubbles

   Hold the syringe with the needle pointing up, tap the barrel gently until the bubbles are at the top, and carefully push out the air. Return excess solution to the vial.

5. Step 5

   Fill the cartridge

   Hold the cartridge upright, rubber septum at the top, plunger at the bottom. First push the thin venting needle through the septum, then insert the syringe next to it. Let the solution run slowly down the inner wall – the displaced air escapes via the second needle. Pull out the syringe first, then the venting needle.

   Don't fill the cartridge to the very last millimetre and don't shake it. Use the Tracker to print a label with contents and date.

6. Step 6

   Insert the cartridge and screw on the needle

   Place the cartridge in the holder septum first, screw the pen together and, if necessary, reset the threaded rod according to the instructions. Screw on a new pen needle straight, remove the outer and inner protective caps.

7. Step 7

   Prime the pen

   Hold the pen with the needle pointing up, tap the cartridge, dial the small amount stated in the pen instructions and release it – repeat until a drop appears at the needle tip. A freshly filled cartridge often needs several rounds.

8. Step 8

   Dial the amount and inject

   Dial the desired number of clicks (on many pens 1 click = 0.01 mL – check in the calculator under “Pen”). Disinfect the injection site, insert the needle at a 90-degree angle, press the button all the way down and hold for 10 seconds so nothing leaks back. Then unscrew the needle and put it in the sharps bin.

• Keep the filled cartridge in the pen or separately in the fridge at 2–8 °C, protected from light, do not freeze
• Never leave the needle on the pen – otherwise air gets in or solution leaks out
• Never share pen and cartridge with others
• Be realistic about shelf life – see the shelf-life guide

• Filling the cartridge without a venting needle – the pressure pushes the plunger out or solution squirts
• Not letting the stopper dry – alcohol gets into the solution
• Transferring cloudy or flaky solution
• Refilling used cartridges

Make sure the pen has CE marking as a medical device – many cheap pens are only declared as “laboratory tools”. Pre-filled pens from private individuals are an additional risk, because nobody can check how they were filled.