PHARMACOKINETICS

Question 1

What is a prodrug and where are they stable?

Answer 1

This is a drug that only becomes an active metabolite after its intake. It is metabolised in the body and then becomes active

These are usually more stable in the GI tract and can migrate to other regions of the body better

Question 2

What is an inactive metabolite and where are they formed?

Answer 2

Inactive metabolite - this is when drugs are broken down and so are no longer active. They no longer have a therapeutic effect

First pass metabolism in the liver produces active metabolites

Question 3

Give an example of a drug that is an active metabolite

Answer 3

DIAZEPAM contains active metabolite components such as desmethyldiazepam

Question 4

What is a toxic metabolite, give an example of a toxic metabolite

Answer 4

Example = paracetamol

Toxic metabolites form as intermediates of side products or end products of metabolism. In paracetamol, its breakdown products form a compound that reacts with the glutathione which is normally an antioxidant.

Question 5

Example of a pro drug

Answer 5

L - DOPA

Question 6

Drugs are given in intervals, what is the dose interval affected by?

Answer 6

Plasma half life - this is the time taken for the drug to be eliminated from the plasma

Question 7

What are the 5 rights of drug administration?

Answer 7

• Right patient
• Right drug
• Right route of administration
• Right dose
• Right time