Drugs

Question 1

Define affinity

Answer 1

How hard a drug binds to a receptor

Question 2

Describe Kd

Answer 2

Concentration at which half the receptors are occupied, lower Kd = Higher affinity

Question 3

Define efficacy

Answer 3

Ability of a drug to elicit a response

Question 4

Describe EC50

Answer 4

Concentration of the drug that elicits a 50% response, Lower EC50 = higher potency

Question 5

Define potency

Answer 5

Combination of affinity and efficacy

Question 6

Describe the use of spare receptors

Answer 6

Increases sensitivity

Question 7

Describe non-competitive anatagonists

Answer 7

Can’t be overcome by increase in ligand concentration, bind to allosteric sites

Question 8

Describe competitive agonists

Answer 8

Can be overcome by increase in ligand, bind to orthosteric sites

Question 9

Describe tolerance

Answer 9

Reduced response to a drug, can be by reduced receptor number or induction of enzymes

Question 10

Describe desensitisation

Answer 10

Reduced response by receptors

Question 11

Describe pharmacuetical factors

Answer 11

Factors involved in getting drug to the patient

Question 12

Define oral bioavailability

Answer 12

Amount of drug reaching the circulation unchanged

Question 13

Describe precipitant drugs

Answer 13

Some drugs bind to albumin, if one drug is already bound it can be displaced by a new drug increasing the concentration of the first drug

Question 14

Describe first order kinetics

Answer 14

Rate of elimination is proportional to the amount of drug present

Question 15

Describe zero order kinetics

Answer 15

Rate of elimination is constant