Injecting with pens and cartridges
The insulin pen is often more convenient than needles. Rather than taking insulin out from a bottle, you use a cartridge of
insulin that fits into a pen-like device. A special needle-tip screws onto the end of the pen. By adjusting the dial on the
side of the pen, you can control the dose. You then push down on the end of the pen (like a plunger) and the insulin is delivered.
There are different-sized pens. Many children find that pen injections hurt less than syringes. This may be because the needle
never has to go through the rubber stopper of an insulin bottle and so it stays sharper. Pen injectors are also easier to
carry, more discreet, and quicker to prepare than insulin syringes. The main problem is that pens are designed to give only
a single type of insulin at a time. Many children are on a combination of insulins, at least in the morning. Premixed insulin
preparations are available. However, they are usually not suitable for children, who need to be able to change the ratio of
the mix. All the same, pen injections are the insulin delivery devices of choice for most children when they are receiving
only 1 kind of insulin. Some may even choose to use 2 separate pens, rather than combining 2 kinds of insulin in a syringe.
Cartridges versus bottles
Insulin manufacturers don’t suggest substituting cartridges for bottles. However, many people find that it’s less costly to
use pen cartridges (3.0 mL) in place of 10 mL bottles if they need less than 10 or 15 units of NPH or Regular or Lispro insulin.
The unopened cartridges can be stored in the refrigerator until the expiry date. The open cartridge is discarded after 4 weeks.
If you use cartridges, don’t try to put any air into the cartridge before taking out the insulin. Simply insert the needle
and take out the insulin. Inserting air may cause the cork at the other end of the cartridge to pop out. In this case the
entire cartridge will be ruined.
