Pharmacodynamics

Question 1

What is pharmacodynamics?

Answer 1

The study of the effect, and mechanisms of action.
i.e what the drug does to the body

Question 2

The targets of drug action

Answer 2

1. Simple chemical neutralisation
2. Enzyme inhibitors-antibiotics
3. Receptor occupying drugs related to neurotransmitters
   Agonists(direct and transduction) and antagonists(binds to the receptor but does not activate the receptor)
4. Modulators of certain transport systems e.g. Na+/K+-ATPase
5. Ion channel interaction e.g. local anaesthetics

Question 3

What is a receptor

Answer 3

Protein molecules that respond to endogenous chemicals(transmitters) in a lock and key fashion

Question 4

What is affinity?

Answer 4

Number of bonds and goodness of fit between drug and receptor

Question 5

What is specificity

Answer 5

Ability of a drug to bind to one specific type of receptor

Question 6

What is selectivity?

Answer 6

No drug is truly specific, but many have relative selectively on one type of receptor

Question 7

General functions of receptors

Answer 7

1. Fast system of nerves
   Neurotransmitters stimulate receptor, NT released into small space
2. Slow endocrine system e.g glucose
   Hormones stimulate receptor, diluted in blood and transported through body
   Chemo-recognising properties are very specific

Question 8

Types of receptors

Answer 8

Coming up!

Question 9

Ligand-gated ion channels

Answer 9

1. Takes milliseconds
2. E.g nicotinic and ACh receptor
3. Hyperpolarisation and depolarisation

Question 10

G-protein-coupled receptors

Answer 10

1. Seconds
2. E.g Muscarinic and ACh receptor
3. Change in excitability

Question 11

Kinase-linked receptors

Answer 11

1. Hours
2. E.g cytokine receptor
3. Protein phosphorylation> gene trascription> protein synthesis> cellular effects

Question 12

Nuclear receptors

Answer 12

1. Hours
2. Oestrogen receptor
3. Nucleus involvement

Question 13

Agonists

Answer 13

Drugs that bind to receptors and activate them to produce a response

Question 14

Antagonists

Answer 14

Drugs that bind to receptors but do not activate them. They block receptor activation by agonists

Agonists on a receptor- full activation
Agonists+ antagonists- less activation
Antagonists alone- no activation

Question 15

Affinity

Answer 15

Number of bonds and goodness of fit between drug and receptor

Question 16

Efficacy

Answer 16

The ability of agonists, once bound to activate receptors

Question 17

Potency

Answer 17

Concentration of a drug needed to elicit a response

Question 18

Changes in receptor numbers

Answer 18

Type and the number of receptor present is net effect receptor synthesis and destruction

Question 19

Down-regulation

Answer 19

Chronic stimulation by agonists cause a decrease in receptor numbers

Question 20

Up-regulation

Answer 20

Chronic inhibition by antagonists causes an increase in receptor numbers

Question 21

Drug effects

Answer 21

Drug toxic effects are harmful
Drug side effects are generally uncomfortable not harmful
Adverse effects= side effects + toxic effects
Medical effect of a drug is defined as its therapeutic effect

Question 22

Factors that can influence drug response

Answer 22

Age
Gender
Weight
Genetic variation
Tolerance
Underlying deseases
Placebo effect
Compliance
Drug resistance