measuring drug action

Question 1

what are are the 2 subtype of nicotinic acetylcholine receptors

Answer 1

• neuronal
• muscle

Question 2

waht are the 5 subtypes of muscarinic acetylcholine receptors

Answer 2

M1-M5

Question 3

what is selectivity

Answer 3

ability of a drug to bind to one receptor subtype without affecting another receptor subtype

Question 4

at the molecular level how can we measure drug response

Answer 4

receptor binding using radioactive drug

Question 5

at the cellular level how can we measure drug response

Answer 5

measuring levels of intracellular messenger (eg: cAMP)

Question 6

at the organ level how can we measure drug response

Answer 6

measure contraction of smooth muscle

Question 7

at the whole body level how can we measure drug response

Answer 7

measure peak flow but also heart rate, blood pressure etc

Question 8

what is the term for how well a drug and receptor bind together?

Answer 8

affinity

Question 9

define potency

Answer 9

concentration required to get an effect

Question 10

what is efficacy

Answer 10

maximum effect of a drug

Question 11

what type of drug has less efficacy than a full agonist

Answer 11

partial agonist

Question 12

what type of drug has no efficacy

Answer 12

an antagonist

Question 13

what percentage or more of receptors need to be occupied by antagonists to get a clinical effect for an antagonist dose

Answer 13

typically need to occupy >75% of receptors

Question 14

• what does the effect of an antagonist dose seen depend on?

Answer 14

depends on concentration of agonist

Question 15

• what can prolonged treatment with an agonist lead to?

Answer 15

desensitisation and then tolerance

Question 16

outline how you can measure drug response

Answer 16

1. Transfect cells with DNA for receptor (either muscle or neuronal)
2. Cell synthesises receptors and they are transported to cell membrane
3. Load cells with fluorescent dye which changes intensity in response to cellular signalling.
4. Add drug  measure response

Question 17

what is IC50

Answer 17

The concentration of drug that gives half the maximum inhibition