Week 1 - Pharmacodynamics

Question 1

What is Pharmacodynamics

Answer 1

The study of the interaction between a drug and its molecular target and of the pharmacological response (i.e. what the drug does to the body)

Question 2

What can affect the pharmacological effect of a drug

Answer 2

• The nature of the interaction with the target
• The affinity of the drug for the target
• The concentration of a drug at the site of action

Question 3

Define Receptor Agonist

Answer 3

A drug binds and activates the receptor producing the same response as the endogenous (natural) ligand.
- Examples of endogenous ligands:
- Hormones (e.g. oestrogen)
- Neurotransmitters (e.g. dopamine)

Question 4

Define Receptor Antagonist

Answer 4

• Bind to the receptor (high affinity for the receptor) without eliciting a response (no efficacy).
• > Prevents the binding of an agonist to the receptor > blocks activation
• An example of a receptor antagonist:
• Naloxone; this drug is a μ-opioid receptor antagonist > can reverse the harmful effects by the opioid overload

Question 5

What are the different drug interactions

Answer 5

The binding of a drug with its target will either:
- Make something happen (‘switch the target on’)
- Stop something from happening (‘switch the target off’)

Question 6

How do clinically used drugs that target enzymes, transporters, and channels produce their effects?

Answer 6

Clinically used drugs that act on enzymes, transporters and channels elicit their effect by switching the target off;

 Called‘inhibitors’:
◼ When they act on an enzyme (e.g. atorvastatin is an enzyme inhibitor) or transporter’ (e.g. citalopram is a serotonin reuptake transporter inhibitor)

 Called‘blockers’:
◼ When they act on a channel (e.g. verapamil is a calcium channel blocker)