4: Introduction to Pharmacology

Question 1

Examples of Neurotransmitters: Acetylcholine

Answer 1

Important in short-term memory, and also the neurotransmitter responsible for responses to parasympathetic division of the autonomic nervous system.

Question 2

Examples of Neurotransmitters: Serotonin

Answer 2

Important in mood, sexual behaviour and feeding, also affects BP.

Question 3

Examples of Neurotransmitters: Dopamine

Answer 3

Involved in reward and motivation, mood, movement.

Question 4

Pharmacodynamics

Answer 4

• The biological and physiological effects of the drug

- The effects it has, and the mechanism by which it produces them, are its pharmacodynamics

Question 5

Pharmacokinetics

Answer 5

The absorption, distribution, metabolism and excretion of the drug (ADME).

Question 6

Agonist

Answer 6

• A substance that acts like another substance which initiates a physiological response when combined with a receptor
• If a drug binds to its receptor and produces the same effect as the the natural compound that would normally act there, it is an agonist at that receptor

Question 7

Antagonist

Answer 7

• Blocks or prevents the natural substance from binding to its receptor.
• If a drug binds to its receptor, but produces no effect (other than stopping anything else from binding), it is an antagonist at that receptor

Question 8

Affinity

Answer 8

• The tendency for a drug to bind with a receptor is its affinity for the receptor
• High affinity, readily bind to many of its receptors and may even kick off substances with a lower affinity

Question 9

Selectivity

Answer 9

• If a drug is able to bind to more that one receptor type, the degree to which it “prefers” binding to one over the other - selectivity
• And this will be determined by the difference in its affinity for the different receptors

Question 10

Potency

Answer 10

• Measured by the amount of drug needed to produce a particular size of effect
• It will therefore depend on both the affinity and efficacy of a drug

Question 11

Effectiveness

Answer 11

• A drug can only bind to its receptors and have an effect if it can get there
• Therapeutic effect - a certain number of receptors will need to be occupied, so a certain concentration of the drug will need to be achieved at the target site of the drug
• Knowing what happens to the drug while it’s on its way to its receptors

Question 12

Making Sure a Drug Gets to its Site of Action: Difficult for 2 Reasons

Answer 12

1. Knowing what happens to the drug while it’s on its way to its receptors
2. From the moment the drug enters the body, it is being worked on by the body in ways which will tend to prevent it from reaching its site of action

Question 13

What Can Get Through the Cell Membrane?

Answer 13

• Lipid-soluble (lipophilic) molecules
• Small polar (water-soluble, hydrophilic) molecules
• Gases

Question 14

What Can’t Get Through the Cell Membrane?

Answer 14

• Large polar (water-soluble) molecules
• Glucose
• Ions

Question 15

How Do Ions Get Through the Membrane?

Answer 15

By going through ion channels, which, when open, create water-filled passages through the lipid bilayer.

Question 16

Possible Distributions of a Drug

Answer 16

1. Bloodstream/plasma
2. Distributed around the tissues
3. Concentrated in a particular tissue e.g. thyroid gland