Insulin Pens.

First introduced in 1985 this form of insulin delivery is taking over from the syringe.

Think back to the days of the fountain pen and you will be better able to comprehend the insulin pen. You have a cylindrical 'pen' shaped device with an insulin cartridge inside, in place of the ink and a needle on the end, in place of the nib.

For those of you who are too young to remember a fountain pen then imagine something the size of a marker with a needle instead of the felt tip and a container inside with insulin in instead of ink - got it?

As usual, you may read in a linear fashion, or jump to where you wish to be using the following on page links:-

Non-disposable Pens.
Disposable or Prefilled Pens.
Basic instructions on how to use either type of pen.
Useful facts.
General advantages of pens.
General disadvantages of pens.
Insulin 'pens' with a difference.
Useful sites.

There are two main divisions in insulin pens - Disposable and non-disposable. Lets look at each of them in turn.

1. Non-disposable Pens.

With these you keep the 'pen' bit but change the inside cartridge.
The cartridge, usually made of glass, comes pre-filled with insulin and you simply load it into the pen. When the insulin is finished you remove that cartridge and put in another full one.

The pens come with a cover, rather like that of an ordinary pen, that goes over the cartridge when you are not using the pen.

They all use disposable needles.

The advantages over prefilled pens are that you do not have to buy a new pen if your insulin type changes (as long as your new insulin comes in the same cartridge size - see cartridges below). Also these pens are made more durable than the 'throw away' ones (not surprising considering they are meant to last longer).

There is a minor disadvantage with these pens in that they may lose sterility with use and despite their durability, they may become damaged over time.

These types of pens are made by Novo Nordisk, Owen Munford and Disetronics, (which makes pens for other companies as well, such as Aventis).

If you have heard of the BD Pen and BD Pen Mini (Becton, Dickinson and Company) and are wondering why I do not add them to my list it is because they used to make these pens but have stopped doing so. They probably felt more money was to be made in the making and supplying of pen needles to the market than the pens themselves, the needles being the main disposable bit and more in line with their usual production anyway.

It seems that nowadays pen manufacturing is being taken over by the insulin producers. It makes sense I suppose to have both aspects needed for the device to be produced under the same roof.

Just like syringes, pens vary in the capacity of the cartridge, the needle length and gauge and the dosing increments.

The cartridge can contain either 150 units (1.5ml) or 300 units (3.0ml). The latter appears to be becoming the standard.

They can allow 1/2, 1 or 2 unit dosing.

Needles can be 29g x 12.7mm; 29g by 12mm; 29g x 10mm; 29g x 8mm.
30g x 8mm; 30 x 6mm; 31g x 8mm; 31 x 6mm; 31 x 5mm.

Needles are double ended, one end to piece the rubber stopper of the cartridge and one to inject through the skin.

The insulin in the cartridges available for the different pens also varies. Not all pens will take all types of insulin cartridge. For example:-

1. The Owen Munford Autopens will take Eli Lilly or Novo Nordisk insulin cartridges and, in the UK, Wackhardt's (used to be CP Pharmaceuticals) bovine or pork insulin cartridges.

2. The Novo Nordisk NovoPen 1.5, NovoPen 3 and NovoPen Junior take Novo Nordisk insulin only.

3. The Aventis OptiClik pen will take Lantus or Insuman insulin only.

In addition Disetronic have a unique system, called a Reusable open system. They produce disposable 3.15 mL cartridges that the user can fill themselves with any U100 insulin.

The cartridges.

If you take a normal insulin vial and imagine it stretched to fit within a fountain pen it you will have a pretty good idea of what they look like. The end where you put the needle in is almost exactly the same as the top end of a vial, with it's rubber stopper surrounded by a metal rim. The other end differs slightly in being open but sealed with a movable rubber stopper which is pushed down a measured amount (depending on how much insulin you are taking out) by the pen's plunger.

These cartridges are usually sold in packs of at least 6 and need to be kept in the fridge until used.

Insulin cartridges come in either 150 units or 300 units and are specific for the pen size so you cannot use a 150-U cartridge in a 300-U pen, and vice versa.
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2. Disposable or Prefilled pens.

Looking much the same as their non-disposable counterparts these pens come prefilled from the manufacture. You simply use them until the insulin is finished and then throw them away and start on a new pen.

This makes them very convenient to use, especially if you are someone with a hectic lifestyle who does not want to spend time fussing with syringes or cartridges.
Also great for those with physical problems that make using a syringe or loading a cartridge difficult.

Again the prefilled pens are made by the insulin manufacturers - Eli Lilly, Novo Nordisk or Aventis.

Examples of the type of insulin you can get in these prefilled pens are:-

1. Eli Lilly

Humalog - Contains lispro insulin.
Humalog Mix 75/25 - Contains 25% lispro and 75% longer-acting insulin.
Humulin 70/30
Humulin N - Contains NPH insulin.
Humulin 1

2. Novo Nordisk

Human Mixtard 10, 20, 30 ,40.
Human Insulatard
NovoMix 30

3. Avantis

Lantus Glargine
Insuman Rapid
Insuman Basal
Insuman Comb 15
Insuman Comb 25
Insuman Comb 50
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Basic instructions on how to use either type of pen.

1. Screw in a new needle.
2. Prime pen to remove any air - if necessary.
3. Dial up the amount of insulin you need. This can be seen in the display window and on some pens can be heard as an audible click.
4. Inject needle through skin into subcutaneous layer.
5. Press the spring loaded plunger.
6. Wait at least 5 seconds to make sure all the insulin has been injected.
7. Withdraw needle from body.
8. Remove needle from pen, dispose of it and replace pen cap.
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Useful facts.

1. Be careful when you are putting in a new needle that you do not inadvertently turn the dialling mechanism. This is more of a problem with some pens than others, and particularly so on prefilled ones.

2. Do not store your pen with the needle in it - always remove the needle immediately after use. It makes sense if you think about it. The needle is a passage, even if a minute one, into the insulin cartridge. This allows stuff to get either in (air or bacteria) or out (insulin). This will be accentuated if you live in a place where the temperatures fluctuate because heat can cause insulin expansion which will push the contents out - if you use cloudy insulin such as NPH or 70/30, fluid may leak out but particles stay in, causing changes in the strength of the insulin.
Cold causes contraction and sucks outside air in. And that brings me to the next point.

3. Do NOT store in-use pens in the fridge. Once the rubber stopper has been penetrated the pen should be stored at room temperature until the insulin has all been used. It will keep from 10-28 days in these conditions. Refrigerating it can cause air bubbles to form inside or insulin to leak out.
You DO store unused pens and cartridges in the fridge.

4. If travelling in an aeroplane DO NOT leave a needle in a pen as the change in cabin pressure may cause the insulin in the cartridge to leak out. Also carry your pen PLUS your spare disposable pens or cartridges with you. The 'checked in' baggage in the hold gets to temperatures that can destroy insulin - it sometimes gets lost too!

5. If using cloudy insulin or mixed insulins remember to roll the pen between your hand or shake them prior to use to make sure it is mixed properly. I have read that if you use this sort of insulin and you have less than 12 units left in the pen it is best to discard the pen and start another one as there is too small an amount of insulin to mix properly.

6. Priming the pen will remove any air that may have got in. You do this by holding the pen with the needle pointing upwards. You then tap the barrel a few times, which will move any air bubbles towards the top. Now dial up 2 units and press the plunger. A tiny drop of insulin should appear on the tip of the needle. The pen is now ready for use. If this does not occur then do the procedure again. If you still get no drop then maybe there is a problem with that needle, replace it with a new one and try again.

This is necessary because, besides injecting yourself with air - a waste of time since we were issued with lungs - you also will also be giving yourself a lower dose of insulin.

7. Your pen will not allow you to dial up an insulin dose larger than the amount remaining in it. You then have the choice of throwing that pen or cartridge away, thus wasting the insulin left in it, and starting a new one or using the bit left then dialling up the remainder needed on a new pen or cartridge - this will mean giving yourself two injections but can save quite a lot of insulin.

8. Although needles are disposable , just like with syringe needles, some people do reuse them. They take them out after the injection and recap them until the next injection, when they screw them back in. 5 - 6 times seems to be the generally agreed number before you start getting painful injections and bruising.
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General advantages of pens.

1. Convenience must top the list. You have just the one single object, not multiple syringes and vials. This makes taking insulin so much more 'user friendly', especially when you are out and about.

2. They are inconspicuous and thus more social acceptability You can carry it in your pocket or purse and all anyone would think was that you had a rather large pen. It's a discreet device compared to the syringe. Also people do not associate it with anti-social activities like drug taking - they are more likely to give you the benefit of the doubt than they would with a syringe. This can make pens more acceptable at schools as well. A child can take a pen out of their pocket and discreetly give themselves an injection in the classroom without being conspicuous.

3. Manufacturers can do so much more to a pen than to a syringe to make it attractive and acceptable. There can be practical uses for decorating pens too. The pens made for children, known as paediatric 'POP' pens, come in assorted bright colours and patterns and if a different coloured or patterned pen is used for rapid-acting and intermediate-acting insulin the child will have much less trouble telling them apart and thus using the correct one.

4. It is easier to get repeatable accurate dosing due to the dosing dials. Many pens have an audible click for each one or two units of insulin dialled up, which is a help to those in point 5.

5. They are easier to use for those with visual problems (numbers are easier to see) or with a lack of fine motor skills and also for older adults, children and adolescents.

6. Needles tend to hurt less. This is because they can be shorter and thinner. You get mini, short and long needles. The mini ones are only 5 mm in length- great for children and thin adults. Short range from 6 to 8 mm and are fine for most people.
Also the needle does not have to go through a rubber stopper, as in an insulin vial, before injection, so it remains sharp and keeps it's bevelled edge.

7. They work well as a useful backup if you are on an insulin pump.

8. They do not need to be kept refrigerated once in use. This does away with the cooler bag needed if you are carrying vials of insulin around.

9. Insulin has a shelf life once opened. Most require to be discarded after 28 days while premixed insulins only last for 10-14 days. An insulin vial contains 1000 units, while the largest pen contains only 300 units. That means you are more likely to use up your pen insulin before it expires, especially if you use small doses.

10. Flexibility. You have a choice of either reusable or disposable.
Also using a pen does not rule out the use of a syringe as well. It is not an either/or situation. Some people use the pen to deliver their pre-meal bolas insulin and a syringe for the once a day basal insulin.

11. Due to the above factors people are more willing to comply with their injection regime.
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General disadvantages of pens.

1. Cost. They are generally more expensive than syringes and vials. They are not covered by insurance in some countries, mainly the US. Cost is also affected by the next point.

2. Wastage You get more wastage when you prime the pen and if you have to throw away some of the insulin when the pen is running out.

3. Not all types of insulin are available in pen format.

4. If you need to take a mix of insulin you will need pens which contain all the types you use and will have to give yourself multiple injections.

5. Availability. You cannot be sure of being able to get the pen you need everywhere. This can be a problem for folk who travel around the world a lot.

6. The injection itself takes slightly longer than when using a syringe as you need to wait 5 seconds after depressing the plunger before removing the needle, to be sure of getting all the insulin injected.

7. You need to have a backup pen in case your one fails to work.
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Insulin 'pens' with a difference.

1. The Innolet

Sadly, this has been discontinued. This page is due for updating.

Though classed under Insulin pens it does not look much like a pen.
Novo Nordisk made the Novolin Innolet for people with poor eyesight, poor manual dexterity and those who found learning how to give injections difficult. I would say they have succeeded in their objective. It is easy to see and simple to use.

Being a prefilled device you do not have to fuss with cartridges. It has the biggest dial of any I have ever seen - it looks more like one you would find on an egg timer! The dial, graduated in 1 unit increments, has large numbers, from 0 to 50 eg. 0; 5; 10; 15........50, with line makings in between. This, plus the fact that it makes a very audible click when dialled, makes it a godsend for those with bad eyesight.

It is ergonomically designed with a large grip and a wider end where it rests against the skin than most pens, so even if you tremble a bit it is still easy to inject.

It takes a NovoFine 30 pen needle and the device has a needle compartment that stores a needle for the next use.

To use it you simply turn it up and down a few times to mix the insulin, then take the cover off the bottom, fit the disposable needle, dial up a couple of units, hold it with the needle upwards and tap it gently and then press the plunger on the end of the device. Once the plunger is pressed in completely a drop of insulin should appear at the tip of the needle - it is now primed. Then you dial up your insulin dose (if you turn the dial too far you can simply turn it back to the right number), insert the needle into the chosen injection site, press the plunger and wait until the dial reads zero (about 6 seconds), then remove.

It is sold in packs of 3 or 5 and comes prefilled with 300 units of two of the most common forms of insulin, Novolin N or Novolin 70/30. Novolin 70/30 can remain unrefridgerated for 10 days; Novolin N for 14 days. The cartridge has a glass ball in it that helps to mix the insulin when you turn the device up and down.

When it is empty you just throw it away and start another one.

If you want to find a fault you could say that it is bulkier than normal pens so takes up more fridge space, but I think most diabetics would feel it's advantages far outweigh that small disadvantage.

It also does not deliver in half unit increments so is no use for very young children.

2. The Innovo.

Sadly, this has been discontinued. This page is due for updating.

This is another 'pen' that does not look like a pen but more like a compact pager. It is still small enough to fit in a pocket or purse.

Unlike the Innolet it is reusable, not disposable. It takes a 300 unit cartridge of
Novo Nordisk 70/30, N, R, or NovoLog insulin, which is easy to load. You simply open a slide in the side of the device and insert the cartridge. A 1-70 unit dial allows dose dialling in 1 unit increments. Like the Innolet it does not allow for half unit dialling.

It is unique in that it has a built in memory that will remember and display how many units you injected at the last dose and how long it is since that last dose, wonderful for those of us with poor memories who cannot remember if they have had their insulin dose or not (remember hypoglycaemia can sometimes make one very confused).

Also coming up on the large LCD display window is the indication that the insulin is being delivered, how many of units have been delivered and a 6-second countdown feature that tells you when the entire dose has been delivered and when the needle may be withdrawn.

It also has a scale that indicates how much insulin is left in the cartridge. A couple of complaints I have read about this device include the difficulty of pressing the plunger down - apparently it takes some force. You also cannot put the cover back on without removing the needle and then you have to find somewhere to dispose of said needle, not easy if you are out and about.

3. The InDuo.

Very like the Innovo but with bells on - in other words it is the one and only (as of the moment) insulin delivery device that incorporates a blood glucose meter!

Novo Nordisk and LifeScan, Inc. got together and came up with this device which is meant to encourage diabetics to take their blood glucose levels before injecting insulin and to adjust their dose to suit, leading to better control - it is nice to see two such large companies working together for the good of diabetics. It basically has all the features and advantages inherent in the separate articles.

It takes the same cartridges as the Innovo and works in the same way, with the same memory function. The meter is the same as the One Touch Ultra, with it's need of a very small blood sample and quick result time - see Blood Glucose Meters.

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Useful sites.

For an Insulin pen chart in pdf format that tells you what insulin pens are available in the UK, what insulin they use and whether they are available on prescription.
Diabetes UK

Insulin pens available in Australia, their pros and cons.
Diabetes Australiavic.

Insulin pens available from Novo Nordisk.
Insulin Pens and Needles.

Insulin pens reference guide from Diabetes Health - has pictures plus information. Needs Adobe Acrobat to open.

Information and picture of the InDuo device.

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