Metabolism of drugs

Question 1

3 main types of excretion/metabolism

Answer 1

Question 2

Example of drugs inactivated by metabolism

Answer 2

Phenytoin, warfarin, suxamethonium

Question 3

Examples of drugs activated by metabolism

Answer 3

Given as prodrug: Clopidogrel, morphine, dabigatran

Metabolsim leads to toxic metabolites: paracetamol, halothane

Question 4

Metabolism leads to the damaging substance

Answer 4

NAPQI

Within therapeutic doses this is mopped by glutathione

Question 5

Antidote for paracetamol OD

Answer 5

N-acetylcysteine

Question 6

Purpose of phase I

Answer 6

Introduction or unmasking of functional group, oxidative reaction

I.e. add polar group to increas water solubility

Question 7

Purpose of phase II

Answer 7

Conjugation with endogenous chemical at functional centre

GREAT increase in solubility to allow excretion by e.g. bilary or renal route

Question 8

How many Cytochrome P450s in humans

Answer 8

15, 6 of importance to drugs

Question 9

Drugs that undergo NON-CYP450 metabolism

Answer 9

Question 10

Function of phase II and examples

Answer 10

Question 11

Which drugs are most likely involved in interactions

Answer 11

Drugs metabolised by only a single CYP rather than several