Pharmacokinetics I

A. True. If metabolism of lipid-soluble drugs did not occur, they would remain in the body indefinitely; to be excreted, they must be chemically altered so that they become water-soluble.

B. False. Oxidation is much the commonest form of Phase I reaction.

C. True. Phase I metabolism involves chiefly the cytochrome P450 family of membrane-bound enzymes.

D. False. Some drugs (pro-drugs) have no pharmacological activity until they undergo Phase I metabolism, whereas others have Phase I metabolites that have toxic effects that their parent drugs did not possess.

E. True. Phase I metabolites, and some parent drugs, combine with endogenous substrates, such as glucuronide or sulphate during Phase II.

	T	F
A. Metabolism makes lipid-soluble drugs more water-soluble
B. Reduction is the commonest form of Phase I reaction
C. Phase I metabolism involves membrane-bound enzymes in the smooth endoplasmic reticulum of the liver cells
D. Products of Phase I metabolism cannot have activity that the parent drug did not possess
E. Phase II metabolism involves combination of molecules of Phase I metabolite with an endogenous substrate

Introduction

What is 'pharmacokinetics'?

What are the four phases of pharmacokinetics?

What patient factors affect pharmacokinetics?

Case study 1

Summary

Pharmacokinetics I

Knowledge Check 4