Pharmacodynamics

Question 1

What are the different types of adverse effects?

Answer 1

-Quantitative- expected, unwanted consequences of the drug or toxicity due to high doses (eg hypertension if too much metaraminol)

-Qualitative effects ie unwanted effects due to hypersensitivity or idiosyncrasy

Question 2

WHat is tolerance?

Answer 2

Decreased effect following repeated exposure to a drug

Question 3

What is tachyphylaxis?

Answer 3

Decreased responsiveness after a single dose of a drug

Question 4

What is sensitisation?

Answer 4

Increased response after repeated exposure to a drug

Question 5

What is a class 1 receptro and example

Answer 5

ligand gated ion channel eg nACH receptor

Question 6

WHat is class 2 receptor and example

Answer 6

GPCR (metabotropic)
eg mACh receptor

Question 7

t3 receptor and example

Answer 7

kinase linked receptor-cytokine receptors

Question 8

T4 receptor and example

Answer 8

Nuclear receptor
Oestrogen receptor

Question 9

DIfferent types of G protein?

Answer 9

Gi, Gs, Gq

Question 10

WHat does an activated Gs do?

Answer 10

Increase cAMP

Question 11

What does activated Gi do?

Answer 11

decrease cAMP

Question 12

What does activated Gq do

Answer 12

increase DAG or IP3

Question 13

How does an activated alpha unit of a g protein return to resting state

Answer 13

Phosphorylase on the alpha subunit cleaves a phosphate from GTP to form GDP/the inactivated form of the subunit. This can then recombine with the BY subunit

Question 14

What is ED50

Answer 14

immediate effective dose 50%
Dose of drug that produces a specified response in 50% of the population to which it was administered

Question 15

What is EC50

Answer 15

Median effective concentration 50%
Concentration that induces a response halfway between 0 and max

Question 16

What is the therapeutic window?

Answer 16

Difference between the dose that produces desired effects and the dose that produces undesired effects

Question 17

How do we calculate the therapeutic index

Answer 17

LD50/ED50

(lethal dose in 50%)

Question 18

Examples of drugs with narrow therapeutic windows/low therapeutic index

Answer 18

Warfarin, aminoglycosides, theophylline, phenytoin

Question 19

What is affinity

Answer 19

Strength of association btw drug + receptor

Question 20

WHat is Kd

Answer 20

DIssociation constant
Drug dose at which 50 % of receptors are bound + 50% unbound

Question 21

What is efficacy

Answer 21

The ability of a drug to interact with a receptor and produce a response

Question 22

What is potency

Answer 22

The ability of a drug to produce a certain effect at a certain dose. Determined by pharmacokinetics

Question 23

TYpes of antagonist?

Answer 23

Competitive
Non competitive
Irreversible

Question 24

Partial agonists and affinity?

Answer 24

GEnerally lower than full agonists, though they can be the same

Question 25

Hepatic enzyme inducers?

Answer 25

Phenytoin CIgarette smoking Rifampicin CHronic alcohol Enflurane Halothane Phenobarbitol Thiopental Phenytoin Carbamazepine Steroids

Question 26

Hepatic enzyme inhibitors

Answer 26

MEtronidzaole Isoniazid Chloramphenicol Phenelzine Trancypromine Cimetidine Grapefruit juice Amiodarone

Question 27

Drugs affected by acetylator status?

Answer 27

Hydralazine Isoniazid sulphonamides phenelzine dapsone procainamide

Question 28

Rapid acetylator status inheritance?

Answer 28

AD- 40% o f pop

Question 29

Slow acetylator status inheritence

Answer 29

AR

Question 30

WHat are the different types of drug anatagonism?

Answer 30

Competitive Non competitive Physiological Chemical

Question 31

WHat is competitive drug antagonism

Answer 31

Drugs bind reversibly and the interaction can be overcome by increasing the concentration of the agonist

Question 32

What is non competitive drug antagonism?

Answer 32

Irreversible binding of drugs (usually covalent) that cannot be overcome

Question 33

WHat is physiological antagonism od drugs?

Answer 33

WHere the opposing actions cancel each other out- eg norad increasing BP histamine decreasing BP

Question 34

WHat is chemical antagonism of drugs

Answer 34

Direct interaction which removes the drug or prevents it reaching the target ( eg penicillamine chelating lead)

Question 35

Examples of drugs acting to inhibit enzymes?

Answer 35

Allopurinol (xanthine oxidase) Physostigmine (anticholinesterase) Indomethacin (cyclooxygenase) Enoxomone (phosphodiesteradse)

Question 36

Drugs that exhibit tachyphlyaxis?

Answer 36

GTN Ephedrine Trimetaphan

Question 37

Example of a mixed agonist-antagonist?

Answer 37

Opioids (Pentazocine, Nalbuphine and Buprenorphine), Mirtazepine, Pindolol and Xameterol