Introduction

Question 1

Define the following terms:

a) Pharmacology
b) Pharmacodynamics
c) Pharmacokinetics
d) Pharmacy

Answer 1

a) Pharmacology: the study/science of chemicals that interact with the human body
b) Pharmacodynamics: what a drug does to the body (biological effects and mechanism of action)
c) Pharmacokinetics: what the body does to a drug (absorption, distribution, metabolism, excretion of drugs)
d) Pharmacy: the science and technique of preparing, dispensing and reviewing medicinal drugs

Question 2

What is a drug?

What is a medicine?

What is usually required for a drug to be useful?

Answer 2

Drug: any single synthetic, or natural substance of lnown structure used in the treatment, prevention or diagnosis of disease

Medicine: a chemical preparation containing one or more drugs used with the intention of causing a therapeutic effect. Medicines usually include agents additional to the active drug

For a drug to be useful as a therapeutic agent, it must usually act with a degree of selectivity

Question 3

What do drugs bind to and how does this work?

-

-

-

Answer 3

Drugs act by binding to target molecules, selectivity results from:

• the chemical structure of the drug (binding site specificity)
• the target recognising only ligands of a precise structure (ligand specificity)

Many drugs act by binding to regulatory proteins:

• enzymes, carrier molecules, ion channels, receptors

Important additional targets are:

• RNA, DNA

Question 4

What are receptors?

What are the two types of drugs that can act on receptors?

-

-

Answer 4

Receptors are macromolecules/proteins which are normally activated by transmitters or hormones and mediate a biological action

Drugs acting on receptors can be either agonists or antagonists:

• agonist: a drug that activates a reeptor and causes a response
• antagonist: a type of drug which combines with a receptor but does not activate it, thus blocking the action of the agonist bby binding to the same receptor

Question 5

What do agonists do?

Answer 5

Agonists bind to receptors to activate them

Question 6

What is affinity?

Describe:

• low affinity
• medium affinity
• high affinity

What is efficacy?

• low efficacy:
• high efficacy:

Answer 6

Affinity is the srength of association between ligand and receptor.

• low affinity: fast dissociation rate (does not stay on receptor long)
• medium affinity: moderate dissociation rate
• high affinity: slow dossociation rate

Efficacy is the ability of an agonist to evoke a cellular response.

• low efficacy: small response
• high efficacy: much bigger response

Question 7

What do antagonists do?

What do they lack?

Answer 7

Antagonists bind to receptors but di not activate them, they also block receptor activation by agonists.

Antagonists possess affinity but lack efficacy.

Question 8

Explain the relationship between agonist concentration and receptor occupancy

Answer 8

At low concentration of agonist, receptor occupancy is low, whereas at high agonist concentration, receptor occupancy is 100%

Question 9

What is competitive antagonism?

Answer 9

• Binding of agonist and antagonist occur at the same site (orthosteric) and is competitive and mutually exclusive

If antagonist binds: receptor is inactive

If agonist binds: receptor is active

Question 10

Describe non-competitive antagonism

Answer 10

Agonist binds to orthosteric site and antagonist binds to separate allosteric site, therefore not competitive. Both may occupy the receptor simultaneously but activation cannot occur when the antagonist is bound.