The Pharmacology of Insulin Flashcards
What is the physiological role of insulin?
- Stimulates uptake of glucose into the liver, muscle, and adipose tissue
- Decreases hepatic glucose output via inhibition of gluconeogenesis
- Inhibits glycogenolysis
- Promotes uptake of fats
What would an ideal insulin treatment be able to do?
Reinstate the normal daily insulin profile to prevent both hyperglycaemia and hypoglycaemia
What are the types of insulin available?
- Animal porcine and bovine
- Recombinant DNA technology
What are the types of insulin produced by recombinant DNA technology?
- Human short acting insulins
- Human rapid acting insulin analogues
- Isophane intermediate acting insulin
- Long acting basal analogue insulins
- Very long acting basal analouge insulins
What has recombinant DNA technology allowed for?
The development and production of analogues
What happens to the insulin molecule analogue when it is produced by recombinant DNA technology?
Its molecular structure is modified to alter the pharmacokinetic properties, primarily affecting the absorption of the drug from subcutaneous tissue
What region of the insulin molecule is altered in recombinant DNA technology?
B26-30 region
Describe the steps in the genetic engineering to produce insulin
- Plasmid from a bacterium is cut using an enzyme
- Human insulin gene is inserted into the plasmic
- The engineered plasmid is inserted into the new bacterium
- The bacterium divides and starts producing insulin
How do the different types of insulin vary?
They exist in various strengths and forms
Give 3 examples of forms that insulin can be
- Vials
- Cartridges
- Disposable pens
What is the problem with there being lots of different types of insulin?
Very confusimng and liable to prescription errors
What is meant by u100, when considering insulin?
100 units of insulin per ml
What is the problem with Humulin R U500 (a form of insulin)?
- It can lead to catastrophic prescription errors if people don’t realise its U500, not U100
How are prescription errors prevented with U200 and U300 insulins?
They are now produced with pen delivery systems
What are the main insulin categories?
- Ultrafast acting
- Rapid acting
- Short acting
- Intermediate acting
- Long acting
- Very long acting
What is the difference between the main insulin categories?
The rate of insulin absorption after injection
How does absorption of insulin into the blood stream occur?
Via subcutaneous injection
When did ultra-fast acting insulin gain a UK license?
In January
How does the pricing of ultra-fast acting insulin compare to rapid acting insulins?
It is the same
Give three examples of rapid acting insulins
- Humalog
- Novorapid
- Apidra
How long does the onset of action take with rapid acting insulins?
5-15 minutes
When should rapid acting insulins be injected?
Just before eating
When does the action of rapid acting insulins peak?
About 60 minutes after administration
What is the duration of action of fast acting insulins?
4 to 6 hours
Give 4 examples of short acting insulins
- Actrapid
- Humulin S
- Hypurin Bovine
- Porcine Neutral
How long does short acting insulin take to work?
30 to 60 minutes
When does short acting insulin need to be injected?
At least 15 to 20 minutes before eating
When does the action of short acting insulin peak?
2 to 3 hours after taking it
What is the problem with the timing of the peak of short acting insulin compared to the administration time?
You will get a very high glucose reading after meal, which can increase in the risk of complications over time
What is the duration of action of short acting insulin?
8 to 10 hours
How often does short acting insulin need to be injected?
Several times daily, to cover meals
Give 3 examples of intermediate acting insulins
- Insulatard
- Humulin I and Insuman Basal
- Hypurin Bovine and Porcine Isophane
When is the onset of intermediate acting insulin?
2 to 4 hours
When does the action of intermediate acting insulin peak?
4 to 8 hours
What is the duration of action of intermediate acting insulin?
12 to 20 hours
Give two examples of long acting insulins
- Glargine
- Determir
What is the onset of long acting insulins?
2 to 6 hours
What is the duration of action of long acting insulins?
Up to 24 hours
Give an example of very long acting insulin
Degludec
What is the duration of very long acting insulin?
50 hours
What is an insulin pump therapy?
A sensor augmented pump therapy with threshold suspend
What are the adverse effects of insulin?
- Hypoglycaemia
- Hyperglycaemia
- Lipodystrohy
- Painful injections
- Insulin allergies
What % of the UK population has diabetes?
4-5%
What % of those in the UK with diabetes are treated with insulin?
30 to 40%
How common are insulin errors in the UK?
Very common, with prescribing errors in approx. 20% of cases
Why are insulin prescribing errors problematic?
Too much will lead to hypoglycaemia, and too little will lead to hyperglycaemia
