Drug Metabolism (notes)

Question 1

What do drug tend to be?

Answer 1

Lipophilic

Question 2

In terms of a drug what does metabolism tend to do to it?

Answer 2

It eliminates or reduces the pharmacological and toxicological activity - converts it to something more polar. Water soluble drugs can be excreted more easily

Question 3

Where are the sites for drug metabolism?

Answer 3

Major: Liver

Gut, kidneys, brain, skin

Question 4

Define hepatic first pass metabolism

Answer 4

Metabolic conversion of the drug into something that is different before the drug enters the general circulation

Question 5

Where are some pre-hepatic locations for first pass metabolism?

Answer 5

Buccal cavity, oesophagus, stomach, intestines

Question 6

How can you administer a drug with low bioavailability?

Answer 6

If it undergoes first pass metabolism to produce a small amount then you can give in intravenously

Question 7

What is the process of metabolic change in a drug?

Answer 7

Phase I –> Phase II –> excretion

Question 8

What is the main function of Phase I?

Answer 8

It is about making or releasing functional groups. They often inactivate drugs and create/release functional groups that serve as attachment points for phase II reactions. Prodrugs are activated in phase I

Question 9

What are the three types of chemical activity in phase I?

Answer 9

Oxidation, reduction and hydrolysis

Question 10

Where does phase I reaction occur?

Answer 10

Liver - enzyme system. See notes

Question 11

Describe the cytochrome P450 enzyme system

Answer 11

See notes

Question 12

Describe the process of cytochrome P450 mediated oxidation

Answer 12

See notes