The Pharmacology of Insulin

Question 1

What is the role of insulin?

Answer 1

Stimulates uptake of glucose into the live, muscle and adipose tissue

Decreases hepatic glucose output via inhibition of gluconeogenesis

Inhibits glycogenolysis

Promotes uptake of fats

Question 2

What would the ideal insulin treatment do?

But what is the reality?

Answer 2

Would be to reinstate the normal daily insulin profile to prevent both hyperglycaemia and hypoglycaemia

Very hard to achieve this without a intricate method, so treatment results and a messy graph of amounts of insulin and glucose

Question 3

What are the different types of insulin available?

Answer 3

Animal porcine or bovine

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 analogue insulins
(The insulin molecule structure us modified to alter the pharmacokinetic properties, primarily affecting the absorption of the drug from subcutaneous tissue)
(B26-30 region altered)

Question 4

What is the problem with the variety of insulins?

Answer 4

TOO MANY

Leads to prescribing errors

Question 5

What are the main categories of insulins?

Answer 5

Short acting
Rapid acting
Intermediate acting
Long acting
Very long acting

(Absorption into blood stream via subcutaneous injection)
Formulation of insulin influences rate of absorption

Question 6

Describe short acting insulin.

Answer 6

Starts to work in 30-60 mins
Need to inject 15 to 30 minutes before eating
Peaks at 2-3 hours
Duration 8 to 10 hours
Needs to be injected several times a day to cover meals
Risk of hypoglycaemic events in between meals

Question 7

Describe rapid acting insulins

Answer 7

Rapid onset of action 5 to 15 mins
Inject just before eating (Can inject after if needed)
Peaks 30 to 90 mins
Duration 4 to 6 hours

Question 8

Describe intermediate acting insulins.

Answer 8

Slower onset 2 to 4 hours
Peaks 4 to 8 hours
Duration up to 12 hours

Question 9

Describe long and very long acting insulins.

Answer 9

Slow onset 2 to 6 hours
Duration up to 24 hours
Very long acting - up to 50+ hours duration (DEGLUDEC)

Less need for snacking in between meals
Creates background insulin, that reduces the risk of hypoglycaemic attacks

Question 10

What are the adverse effects of insulin?

Answer 10

Hypoglycaemia
Hyperglycaemia (If not taken enough)
Lipodystrophy - lipohypertrophy or lipoatrophy
Painful injections 
Insulin allergies

Question 11

What is the major problem with insulin?

Answer 11

Very common prescribing errors are insulin.
Hard to get right balance:
- Too much - hyperglycaemia
- Too little - hypoglycaemia