Primary FRCA Course Paper 10 Pharmacodynamics

Question 1

Partial agonists

Can never produce a maximal response at a receptor

Answer 1

True. By definition, they mediate a response which is less than maximal

Question 2

Partial agonists

Cause a parallel shift in the semilogarithmic dose response curve

Answer 2

False. They shift the curve down and to the right

Question 3

Partial agonists

Bind irreversibly to receptor sites

Answer 3

False. They bind reversibly

Question 4

Partial agonists

Generally have a lower affinity for the receptor than the agonist

Answer 4

True. It can have the same affinity as the agonist, though in general it is lower

Question 5

Partial agonists

If a partial agonist has the same affinity for a receptor as the agonist, it’s equilibrium constant will be the same

Answer 5

True

Question 6

The following are examples of hepatic enzyme inducers

Ranitidine

Answer 6

False. Hepatic microsomal enzyme inducers inc: Rifampicin, Chronic alcohol abuse, Enflurane, Halothane, Phenobarbitol, Thiopental, Phenytoin, Cabemazepine, Glucocorticoids, Cigarette smoking

Question 7

The following are examples of hepatic enzyme inducers

Erythromycin

Answer 7

False. Hepatic microsomal enzyme inducers inc: Rifampicin, Chronic alcohol abuse, Enflurane, Halothane, Phenobarbitol, Thiopental, Phenytoin, Carbamazepine, Glucocorticoids, Cigarette smoking

Question 8

The following are examples of hepatic enzyme inducers

Phenytoin

Answer 8

True. Hepatic microsomal enzyme inducers inc: Rifampicin, Chronic alcohol abuse, Enflurane, Halothane, Phenobarbitol, Thiopental, Phenytoin, Cabemazepine, Glucocorticoids, Cigarette smoking

Question 9

The following are examples of hepatic enzyme inducers

Amiodarone

Answer 9

False. Hepatic microsomal enzyme inducers inc: Rifampicin, Chronic alcohol abuse, Enflurane, Halothane, Phenobarbitol, Thiopental, Phenytoin, Cabemazepine, Glucocorticoids, Cigarette smoking

Question 10

The following are examples of hepatic enzyme inducers

Cigarette smoking

Answer 10

True. Hepatic microsomal enzyme inducers inc: Rifampicin, Chronic alcohol abuse, Enflurane, Halothane, Phenobarbitol, Thiopental, Phenytoin, Cabemazepine, Glucocorticoids, Cigarette smoking

Question 11

The following are examples of hepatic enzyme inhibitors

Amiodarone

Answer 11

True. Hepatic microsomal enzyme inhibitors inc: Metroniadazole, Isoniazid, Chloramphenical, Phenelzine, Tranylcypromine, Cimetidine and Grapefruit Juice

Question 12

The following are examples of hepatic enzyme inhibitors

Carbamazepine

Answer 12

False. Hepatic microsomal enzyme inhibitors inc: Metroniadazole, Isoniazid, Chloramphenical, Phenelzine, Tranylcypromine, Cimetidine and Grapefruit Juice

Question 13

The following are examples of hepatic enzyme inhibitors

Metronidazole

Answer 13

True. Hepatic microsomal enzyme inhibitors inc: Metronidazole, Isoniazid, Chloramphenical, Phenelzine, Tranylcypromine, Cimetidine and Grapefruit Juice

Question 14

The following are examples of hepatic enzyme inhibitors

Fludrocortisone

Answer 14

False. Hepatic microsomal enzyme inhibitors inc: Metroniadazole, Isoniazid, Chloramphenical, Phenelzine, Tranylcypromine, Cimetidine and Grapefruit Juice

Question 15

The following are examples of hepatic enzyme inhibitors

Ceftriaxone

Answer 15

False. Hepatic microsomal enzyme inhibitors inc: Metroniadazole, Isoniazid, Chloramphenical, Phenelzine, Tranylcypromine, Cimetidine and Grapefruit Juice

Question 16

Concerning drug dose and response

A plot of % response against drug concentration gives a sigmoid shape

Answer 16

False. Dose response curves are normally plotted as % response against LOG drug concentration. The resultant graph is sigmoid shaped

Question 17

Concerning drug dose and response

Antagonists must have a higher receptor affinity than agonists

Answer 17

False. A drug with high affinity and high intrinsic activity is an agonist. A drug with high affinity but no intrinsic activity will act as an antagonist, however displacement of an agonist also depends on the relative concentrations of the two drugs at the receptor sites

Question 18

Concerning drug dose and response

Intrinsic activity determines maximal response

Answer 18

True.

Question 19

Concerning drug dose and response

Maximal response occurs only when all receptor sites are occupied

Answer 19

False. A maximal response may be achieved by activation of a small proportion of receptor sites (eg the NMJ)

Question 20

Concerning drug dose and response

Partial agonism implies low receptor affinity

Answer 20

False. Partial agonism may be displayed by a drug with low intrinsic activity, but it may well have high receptor affinity making it difficult to antagonize

Question 21

The efficacy (or intrinsic activity)of a drug

Is greater for drug A if A is effective in a dose of 100 micrograms than for drug B if B is effective in a dose of 100 milligrams

Answer 21

False. The dose of a drug required to produce a given effect decribes its potency, not its efficacy. In the example described, drug A is more potent than drug B

Question 22

The efficacy (or intrinsic activity)of a drug

Is a measure of its therapeutic index

Answer 22

False. The therapeutic index of a drug is a measure of its safety (ED50/LD50)

Question 23

The efficacy (or intrinsic activity)of a drug

Is a measure of the amount of a drug required to produce a given effect

Answer 23

False. This describes potency. Efficacy is a measure of the maximal effect of an agonist.

Question 24

The efficacy (or intrinsic activity)of a drug

Describes the ability of a drug to produce its therapeutic effect

Answer 24

True

Question 25

The efficacy (or intrinsic activity)of a drug Is a measure of the bioavailability of a drug

Answer 25

False.

Question 26

Genetic polymorphisms of drug metabolism Exhibit inter-ethnic differences

Answer 26

True. Some drugs are metabolised by enzymes susceptible to polymorphisms which affect their activity. This is the basis of fast and slow acetylation (e.g. hydralazine) and slow and poor metabolism (e.g. debrisoquine). The prevalence of these polymorphisms shows considerable variation between racial groups

Question 27

Genetic polymorphisms of drug metabolism Are not associated with adverse effects

Answer 27

False. The consequences of poor metabolism of a particular drug are clearly dependent on its pharmacological actions: drugs with a steep dose-response curve or a low therapeutic index may well produce toxic effects in poor metabolisers

Question 28

Genetic polymorphisms of drug metabolism Are dependent on the pharmacological actions of the drug

Answer 28

False.

Question 29

Genetic polymorphisms of drug metabolism Are due to altered gene expression

Answer 29

True. Genetic polymorphisms are determined by abnormalities of gene expression and are not dependent on the pharmacological actions of the drug

Question 30

Genetic polymorphisms of drug metabolism Are not clinically important for drugs that are eliminated by the kidney

Answer 30

True.

Question 31

Metabolism of the following drugs are affected by the acetylator status of the individual Digoxin

Answer 31

False. Rapid acetylator status occurs in approximately 40% of the UK population and is inherited in an autosomal dominant pattern. Slow acetylator status occurs in approximately 60% of the UK population and is inherited in an autosomal recessive pattern. Metabolism of the following drugs are affected by the acetylator status of the individual, Hydralazine, Isoniazid, Sulphonamides, Phenelzine, Dapsone, Procainamide.

Question 32

Metabolism of the following drugs are affected by the acetylator status of the individual Hydralazine

Answer 32

True. Rapid acetylator status occurs in approximately 40% of the UK population and is inherited in an autosomal dominant pattern. Slow acetylator status occurs in approximately 60% of the UK population and is inherited in an autosomal recessive pattern. Metabolism of the following drugs are affected by the acetylator status of the individual, Hydralazine, Isoniazid, Sulphonamides, Phenelzine, Dapsone, Procainamide.

Question 33

Metabolism of the following drugs are affected by the acetylator status of the individual Isoniazid

Answer 33

True. Rapid acetylator status occurs in approximately 40% of the UK population and is inherited in an autosomal dominant pattern. Slow acetylator status occurs in approximately 60% of the UK population and is inherited in an autosomal recessive pattern. Metabolism of the following drugs are affected by the acetylator status of the individual, Hydralazine, Isoniazid, Sulphonamides, Phenelzine, Dapsone, Procainamide.

Question 34

Metabolism of the following drugs are affected by the acetylator status of the individual Propranolol

Answer 34

False. Rapid acetylator status occurs in approximately 40% of the UK population and is inherited in an autosomal dominant pattern. Slow acetylator status occurs in approximately 60% of the UK population and is inherited in an autosomal recessive pattern. Metabolism of the following drugs are affected by the acetylator status of the individual, Hydralazine, Isoniazid, Sulphonamides, Phenelzine, Dapsone, Procainamide.

Question 35

Metabolism of the following drugs are affected by the acetylator status of the individual Amiodarone

Answer 35

False. Rapid acetylator status occurs in approximately 40% of the UK population and is inherited in an autosomal dominant pattern. Slow acetylator status occurs in approximately 60% of the UK population and is inherited in an autosomal recessive pattern. Metabolism of the following drugs are affected by the acetylator status of the individual, Hydralazine, Isoniazid, Sulphonamides, Phenelzine, Dapsone, Procainamide.

Question 36

Regarding log dose-response curves Potency is the ability of a drug to produce maximal response

Answer 36

False. Potency is the dose (mg/kg) required to produce a given effect. Morphine and fentanyl have similar efficacy, but fentanyl is approximately 100 times more potent than morphine (10 mg of morphine is equivalent to 0.1 mg of fentanyl). Efficacy or intrinsic activity is the ability of a drug to produce maximal response.

Question 37

Regarding log dose-response curves A partial agonist binds to the receptor with a lower affinity than an agonist

Answer 37

False. Agonists are drugs that produce the maximal response. Partial agonists cannot produce a maximal response, though they may bind to the receptor with the same affinity as full agonists

Question 38

Regarding log dose-response curves In the presence of a competitive antagonist the log dose-response curve for an agonist shows a parallel shift to the right

Answer 38

True. In the presence of a competitive antagonist the log dose-response curve shows a parallel shift to the right so that a higher concentration of agonist is required to achieve the same response

Question 39

Regarding log dose-response curves In the presence of a non-competitive antagonist, the log dose-response curve for an agonist is shifted to the left

Answer 39

False. In the presence of a non-competitive antagonist the log dose-response curve is shifted to the right and the maximal response is reduced

Question 40

Regarding log dose-response curves A partial agonist can act as a competitive antagonist to a full agonist

Answer 40

True. A partial agonist, by binding to receptors but failing to produce a maximal response, can act as a competitive antagonist to a full agonist

Question 41

The following interactions are antagonistic Naloxone and dextropropoxyphe

Answer 41

True. Antagonistic interactions may be classified into the following four categories: Competitive: The drugs bind reversibly and interaction is overcome by increasing the concentration of the agonist. Irreversible (non-competitive): The drugs bind irreversibly (usually covalent bonding) and this cannot be overcome by increasing the concentration of the agonist. Physiological: The interaction of two drugs whose opposing actions tend to cancel each other. e.g. noradrenaline increasing blood pressure and histamine decreasing blood pressure Chemical: Direct interaction of two drugs which either removes or prevents the drug from reaching the target. e.g. chelation of lead by penicillamine.u

Question 42

The following interactions are antagonistic Acetylcysteine and paracetamol

Answer 42

False. Antagonistic interactions may be classified into the following four categories: Competitive: The drugs bind reversibly and interaction is overcome by increasing the concentration of the agonist. Irreversible (non-competitive): The drugs bind irreversibly (usually covalent bonding) and this cannot be overcome by increasing the concentration of the agonist. Physiological: The interaction of two drugs whose opposing actions tend to cancel each other. e.g. noradrenaline increasing blood pressure and histamine decreasing blood pressure Chemical: Direct interaction of two drugs which either removes or prevents the drug from reaching the target. e.g. chelation of lead by penicillamine

Question 43

The following interactions are antagonistic Atenolol and salbutamol

Answer 43

True. Antagonistic interactions may be classified into the following four categories: Competitive: The drugs bind reversibly and interaction is overcome by increasing the concentration of the agonist. Irreversible (non-competitive): The drugs bind irreversibly (usually covalent bonding) and this cannot be overcome by increasing the concentration of the agonist. Physiological: The interaction of two drugs whose opposing actions tend to cancel each other. e.g. noradrenaline increasing blood pressure and histamine decreasing blood pressure Chemical: Direct interaction of two drugs which either removes or prevents the drug from reaching the target. e.g. chelation of lead by penicillamine

Question 44

The following interactions are antagonistic Protamine and warfarin

Answer 44

False. Protamine is used to counteract the effect of heparin. Antagonistic interactions may be classified into the following four categories: Competitive: The drugs bind reversibly and interaction is overcome by increasing the concentration of the agonist. Irreversible (non-competitive): The drugs bind irreversibly (usually covalent bonding) and this cannot be overcome by increasing the concentration of the agonist. Physiological: The interaction of two drugs whose opposing actions tend to cancel each other. e.g. noradrenaline increasing blood pressure and histamine decreasing blood pressure Chemical: Direct interaction of two drugs which either removes or prevents the drug from reaching the target. e.g. chelation of lead by penicillamine

Question 45

The following interactions are antagonistic Tranexamic acid and streptokinase

Answer 45

True. Antagonistic interactions may be classified into the following four categories: Competitive: The drugs bind reversibly and interaction is overcome by increasing the concentration of the agonist. Irreversible (non-competitive): The drugs bind irreversibly (usually covalent bonding) and this cannot be overcome by increasing the concentration of the agonist. Physiological: The interaction of two drugs whose opposing actions tend to cancel each other. e.g. noradrenaline increasing blood pressure and histamine decreasing blood pressure Chemical: Direct interaction of two drugs which either removes or prevents the drug from reaching the target. e.g. chelation of lead by penicillamine

Question 46

Non-competitive antagonists Move the log dose-response curve for a drug to the right in a non-parallel manner

Answer 46

True.

Question 47

Non-competitive antagonists Reduce the gradient of the log dose-response curve

Answer 47

True. Non-competitive antagonists reduce both the slope and the peak of the agonist log dose-response curve and can cause some degree of rightwards shift (non-parallel).

Question 48

Non-competitive antagonists Have an effect unrelated to the agonist plasma concentration

Answer 48

False. Increasing the agonist dose will increase the response, however the maximum response will never be achieved in the presence of a non-competetive antagonist

Question 49

Non-competitive antagonists Prevent a maximum agonist response

Answer 49

True.

Question 50

Non-competitive antagonists Display surmountability

Answer 50

False. They are non-surmountable as no matter how high an agonist concentration exists, the peak response will not be reached

Question 51

The following drugs act via enzyme inhibition Allopurinol

Answer 51

True. Allopurinol inhibits xanthine oxidase

Question 52

The following drugs act via enzyme inhibition Physostigmine

Answer 52

True. Physostigmine is a naturally occurring anticholinesterase drug

Question 53

The following drugs act via enzyme inhibition Indomethacin

Answer 53

True. Indomethacin reduces prostaglandin production by inhibiting cyclo-oxygenase

Question 54

The following drugs act via enzyme inhibition Meptazinol

Answer 54

False. Meptazinol is an opioid agonist.

Question 55

The following drugs act via enzyme inhibition Enoximone

Answer 55

True. Enoxomone is a selective phosphodiesterase inhibitor.

Question 56

An hereditary enzyme abnormality may lead to altered metabolism of Propofol

Answer 56

False.

Question 57

An hereditary enzyme abnormality may lead to altered metabolism of Isoniazid

Answer 57

True. Acetylation of drugs in the liver (e.g. isoniazid and hydralazine) within a population shows a bimodal distribution of plasma drug concentration following a fixed dose of that drug (fast acetylators and slow acetylators).

Question 58

An hereditary enzyme abnormality may lead to altered metabolism of Thiopentone

Answer 58

False.

Question 59

An hereditary enzyme abnormality may lead to altered metabolism of Suxamethonium

Answer 59

True. The activity of plasma cholinesterase is affected by genetric variation which can lead to an increase in the duration of action of suxamethonium

Question 60

An hereditary enzyme abnormality may lead to altered metabolism of Atracurium

Answer 60

False.

Question 61

Competitive antagonists Shift the log dose-response curve right

Answer 61

True. i.e. a higher agonist dose will be required for the same effect

Question 62

Competitive antagonists Can bind to a different recepetor site than the agonist

Answer 62

False. This is true of non-competitive antagonists

Question 63

Competitive antagonists At the neuromuscular junction, weak antagonists tend to have a faster onset

Answer 63

True. In general this is true, as they are given in higher dose so initially there are more molecules to occupy the receptors.

Question 64

Competitive antagonists Shift the log dose-response curve down

Answer 64

False. The same maximal response will be possible, just at higher doses. It is shifted down by a non-competitive antagonist.

Question 65

Competitive antagonists Are compared with one another by the degree of reduction in maximal response

Answer 65

False. They do not reduce maximal response. They are compared using the Dose Ratio of 2, which indicates the degree of right shift of the log dose-response curve

Question 66

Regarding partial agonists If an agonist has an Intrinsic Activity of < 1, it is termed a partial agonist

Answer 66

True. Meaning it's maximal response/effect is less than that of a full agonist.

Question 67

Regarding partial agonists If given in very large doses partial agonists may achieve a full response

Answer 67

False. By definition, they cannot achieve a full response

Question 68

Regarding partial agonists If given in combination with a full agonist, they can act as an antagonist

Answer 68

True.

Question 69

Regarding partial agonists If given in combination with a full agonist, they can act as an agonist

Answer 69

True. If the full agonist is given at a low dose, the partial agonists effects are additive. As the full agonist dose increases, the partial agonist begins to act as a competitive antagonist

Question 70

Regarding partial agonists If given alone, partial agonists can act as agonists or antagonists

Answer 70

False. Alone they act as agonists, with a reduced maximal response. When given with a full agonist can act as agonists or antagonists

Question 71

Regarding drug-receptor interactions Affinity, refers to how well a drug binds to it's receptor

Answer 71

True.

Question 72

Regarding drug-receptor interactions Intrinsic activity refers to the magnitude of effect once a drug has bound to a receptor

Answer 72

True. Sometimes referred to as efficacy. It has a value of 0 - 1

Question 73

Regarding drug-receptor interactions A drug with high affinity will produce a large response

Answer 73

False. A drug may have high affinity with low or no activity, ie be a partial agonist or an antagonist

Question 74

Regarding drug-receptor interactions Partial agonists have a low receptor affinity

Answer 74

False.

Question 75

Regarding drug-receptor interactions Antagonists will have a high receptor affinity

Answer 75

True. But with no intrinsic activity

Question 76

A drug that is 98% protein bound Will double its free drug concentration if protein binding is decreased to 96%

Answer 76

True. If a drug is 50% protein bound, and this is decreased to 48%, the free drug concentration will increase by 4%. On the other hand, if the drug is 98% bound and this decreases to 96%, the free drug concentration doubles from 2% to 4% of total. Drugs which are extensively bound and which are poorly extracted by the liver will display an increased clinical effect if displaced as free drug

Question 77

A drug that is 98% protein bound Will show a 2% increase in free drug concentration if protein binding falls 2%

Answer 77

False. This is a 100% not 2% increase in free drug concentration Drugs which are extensively bound and which are poorly extracted by the liver will display an increased clinical effect if displaced as free drug

Question 78

A drug that is 98% protein bound Must have a pKa > 7.4

Answer 78

False. Drug pKa is in this case irrelevant

Question 79

A drug that is 98% protein bound Might be diazepam

Answer 79

True

Question 80

A drug that is 98% protein bound Might be midazolam

Answer 80

True

Question 81

The following are examples of pharmacokinetic drug interactions Lithium and thiazide diuretics

Answer 81

True. Increased lithium levels are produced owing to an increase in lithium reabsorbtion

Question 82

The following are examples of pharmacokinetic drug interactions Digoxin and amiodarone

Answer 82

True. Amiodarone reduces the renal clearance of digoxin

Question 83

The following are examples of pharmacokinetic drug interactions Phenytoin and cimetidine

Answer 83

True. Cimetidine inhibits cyt P450 leading to phenytoin toxicity

Question 84

The following are examples of pharmacokinetic drug interactions Beta blockers and verapamil

Answer 84

False. The interaction between beta blockers and verapamil is pharmacodynamic.

Question 85

The following are examples of pharmacokinetic drug interactions Ethanol and diazepam

Answer 85

False. The interaction between ethanol and diazepam is pharmacodynamic.

Question 86

The following drugs exhibit tachyphylaxis Glyceryl trinitrate

Answer 86

True.

Question 87

The following drugs exhibit tachyphylaxis Ephedrine

Answer 87

True.

Question 88

The following drugs exhibit tachyphylaxis Succinylcholine

Answer 88

False.

Question 89

The following drugs exhibit tachyphylaxis Trimetaphan

Answer 89

True.

Question 90

The following drugs exhibit tachyphylaxis Hydralazine

Answer 90

False.

Question 91

The rate of diffusion of a drug across a membrane is dependent upon The drug concentration gradient across the membrane

Answer 91

True. Drug diffusion only occurs if a concentration gradient exists. It proceeds until the concentrations are equal

Question 92

The rate of diffusion of a drug across a membrane is dependent upon Fick's Law

Answer 92

True. Rate of transfer obeys Fick's Law of diffusion

Question 93

The rate of diffusion of a drug across a membrane is dependent upon Dalton's Law

Answer 93

False. Dalton's Law of partial pressures states that the pressure exerted by a mixture of gases or vapours enclosed in a given space, is equal to the sum of the pressures which each gas would exert if it alone were present

Question 94

The rate of diffusion of a drug across a membrane is dependent upon The surface area of the membrane

Answer 94

True. Part of Fick's Law

Question 95

The rate of diffusion of a drug across a membrane is dependent upon The degree of ionization of the drug

Answer 95

True. Unionised molecules cross membranes more readily

Question 96

The following are examples of physiological antagonism Morphine and naloxone

Answer 96

False. Morphine and naloxone are acting at the same receptor, thus this is a pharmacological antagonism. Physiological antagonism is the interaction of two drugs whose opposing actions tend to cancel each other. e.g. noradrenaline increasing blood pressure and histamine.

Question 97

The following are examples of physiological antagonism Fentanyl and doxapram

Answer 97

True. Physiological antagonism is the interaction of two drugs whose opposing actions tend to cancel each other. e.g. noradrenaline increasing blood pressure and histamine.

Question 98

The following are examples of physiological antagonism Morphine and pentazocine

Answer 98

False. Morphine and pentazocine are not acting on opposing physiological mechanisms. They are both analgesics. Physiological antagonism is the interaction of two drugs whose opposing actions tend to cancel each other. e.g. noradrenaline increasing blood pressure and histamine.

Question 99

The following are examples of physiological antagonism Ritodrine and syntocinon

Answer 99

True. Physiological antagonism is the interaction of two drugs whose opposing actions tend to cancel each other. e.g. noradrenaline increasing blood pressure and histamine.

Question 100

The following are examples of physiological antagonism Frusemide and amiloride

Answer 100

True - only in the context of sparing potassium. They are both diuretics. Physiological antagonism is the interaction of two drugs whose opposing actions tend to cancel each other. e.g. noradrenaline increasing blood pressure and histamine.