Nuts and Bolts of Therapeutics

Question 1

Drug-receptor interactions depend on…

Answer 1

1. Chemical composition
2. Stereochemical disposition (chirality)
3. Ability for drug to reach receptor binding zone

Question 2

Affinity

Answer 2

Probability of the the drug occupting a receptor at any given time - affected by other drugs, ageing and genetic mutations

Question 3

Selectivity

Answer 3

The degree to which a drug acts on a given site relative to other sites

Question 4

Efficacy

Answer 4

The relative ability of a drug-receptor complex to produce the maximum functional response

Question 5

Agonist

Answer 5

Chemical binds to a receptor and activates it to produce a biological response

Question 6

Partial Agonist

Answer 6

Chemical still binds to receptor but only has partial efficacy

Question 7

Antagonist

Answer 7

Chemical binds and blocks/dampens agonist-mediated responses rather than provoking a biological response

Question 8

Potency

Answer 8

Measure of drug activity - the amount required to produce an effect of given intensity

Question 9

Tolerance

Answer 9

Decreased response to drug with repeated doses

Question 10

Mechanisms of tolerance

Answer 10

1. Decreased receptor numbers (downregulation)
2. Decreased receptor binding affinity
3. Modulation of downstream response to initial signal

Question 11

On-target response

Answer 11

Drug intended to modulate the function of a specific receptor in a particular tissue

Question 12

Off-target response

Answer 12

Drug and/or metabollites modulate the function of a target for which it was not intended

Question 13

Therapeutic index

Answer 13

Ratio of the dose that produces toxicity to the dose that produces a clinically desired or effective response in a group of individuals

Question 14

Dose

Answer 14

Total quantity of an active agent taken in or absorbed at any one time

Question 15

Main routes of drug administration

Answer 15

1. Enteral - substance given by GIT - desired effect is systemic (oral, NG, ND, enema)
2. IV - 100% availability
3. Parental - desired effect is systemic but drug not given via GIT (transdermal, tansmucousal, inhalation)
4. Topical - local effect (transcutaneous/cream, inhalation)