Hi David,
Now you've started with the Byetta jabs, here's a few things that frequently get asked by new starters.
There are air bubbles in the pen chamber - is this normal? Yes perfectly normal. Every time you insert a new needle (and you should use a new needle every time) this allows a small bubble of air to enter the chamber. These build up over the course of a month into quite a big bubble by the 30th day.
Why do I need to use a new needle every time? Because if you leave the needle attached this allows air to enter the chamber, which will make the exenatide "go off". If you remove the needle and re-use it, they get quite blunt after just a couple of uses and injections will be painful.
What type of needles should I use? Use the finest points you can get (29 gauge) as these are less painful. The length will depend on where you are injecting. Around your stomach you generally have more fat so should use an 8mm length needle. If like me you sometimes inject in your thighs, which are are leaner, then use a 5mm needle. The needle length needs to be enough for you to inject into the area between the fat layer and the muscle tissue. The more fat you need to inject through then the longer the needle.
There is a drop of blood floating in the chamber - is this ok? No - you need to stop using that pen immediately and get a replacement. If you report it to Eli Lily Help Desk they will arrange for a replacement pen to be sent to your pharmacy. The blood occurs when you release the pressure on the plunger before the pen is fully withdrawn from the injection site. This creates a partial vacuum which will draw any sub-cutaneous blood into the chamber. Even though it is your own blood, it reacts with the exenatide and will make it "go off" very quickly.
Some parts of my stomach I don't feel the needle at all but in other places it hurts. Your stomach has small capillary veins just under the surface skin. It hurts if you inject through one of these but is painless if you manage to miss them. Rather than just plunge the needle in, I test the area by inserting the needle point just half a millimeter or so and if I can feel it then I know it will be painful. If I try again about a centimeter away then it is generally painless.
What happens if I have an injection and then don't eat within an hour? You could have a hypo. The injection causes your pancreas to go into first phase insulin production. The pancreas will then continue production as it detects food entering the stomach (second phase). If you don't eat then the pancreas won't go into second phase mode, but sufficient insulin can have been produced in first phase to cause a hypo.
If I forget the injection before my meal can I take it after? No - Eli Lily aren't very clear why you shouldn't but they are adamant that it could be dangerous. If you forget then just skip that injection. Missing an odd one won't do you any harm.
My two main meals are breakfast and lunch. Are these ok for my two injections? Only if there is a minimum of 6 hours between each meal. That is why Lily recommend breakfast and evening meal.
Does the pen need to be chilled all the time? Before first use it must be constantly refrigerated. Once in use it can be kept at room temperature (below 25C, 77F) for up to 7 days. This can be 7 continuous day or 7 separate days. So if you are going out for a meal, or going away for the weekend, you can take the pen with you unchilled.
I used an ice pack to keep the pen cool and the liquid has frozen - will it be ok when it has thawed? No - exenatide is a protein and freezing kills it. If you continue to use the pen you might just as well be injecting tap water.
Why is Byetta sometimes called lizard spit? It is an incretin that was first discovered in the poisonous saliva of the Gila lizard in south west USA.
Should I expect to see lower BS immediately? Byetta is very good at lowering and stabilising blood sugar levels that are not extremely high. It is not designed to produce radical reduction in overly high BS levels - for that you would need to take a sulphonylurea or glitazone medication.
Will it help me to lose weight? Weight loss has been found to be a very welcome side effect for most people, but not all. The medication itself doesn't cause weight loss, but it is an appetite suppressor, which means you will feel less like eating, and can manage happily with smaller portions. That is where the real weight loss comes from.
Do I have to progress to the 10mcg pen? Not necessarily. Some people find that 5mcg is sufficient to give the control they need. Some consultants (and it is generally consultants rather than GPs who prescribe Byetta) like patients to try the 5mcg dose for a few months before moving up to 10mcg.
I hope this will cover any questions you may have in the early days, but if not then fire away. Good luch with Byetta - I hope it is as good for you as it has proved to be for me.
BTW I am not very far from you, just up the A24 in Surrey. Unfortunately I don't come under the same PCT, so at the moment I have to pay privately for my prescriptions, although my consultant is trying to put pressure on my GP to push the PCT into paying.
