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Master YLL Pharmacology > FB - Pharmacodynamics: Drug Receptors & Theory > Flashcards

FB - Pharmacodynamics: Drug Receptors & Theory Flashcards

1
Q

What is a drug?

A

A drug is a substance that, when introduced into the body, produces a biological effect.

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2
Q

What is the definition of a drug receptor?

A

A drug receptor is a specific molecular component of the body that a drug binds to, initiating a biological effect.

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3
Q

Describe the mechanism of enzyme-linked receptors.

A

They activate intracellular processes through enzyme activation when a ligand binds.

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4
Q

How is receptor specificity determined?

A

It is the binding of certain drug or ligand to certain type of receptor.

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5
Q

What is drug selectivity?

A

Drug selectivity refers to the concentration-dependent preference of a drug for one target over others.

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6
Q

What is receptor downregulation?

A

Receptor downregulation refers to the reduction in the number of receptors on the cell surface due to prolonged exposure to an agonist. This process decreases cellular responsiveness to the agonist and involves endocytosis, where receptors are internalized and either degraded or recycled.

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7
Q

How is KD (Dissociation constant) related to affinity?

A

Inverse relationship. Smaller the KD = Greater affinity.

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8
Q

What is meant by the ‘concentration-response relationship’ in pharmacology?

A

Concentration–response relationship refers to the relationship between increasing drug concentration and magnitude of response.

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9
Q

What is the purpose of the dose-response curve?

A

Concentration–response curves are used to determine and compare agonist potency (EC50), maximal effect (Emax), antagonist potency, type of antagonism, and whether a drug is partial or full agonist.

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10
Q

What is EC50?

A

The concentration of agonist that produces 50% of the maximal response is referred to as EC50.

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11
Q

What is potency and how is it related to EC50?

A

Agonist potency is most commonly measured as the effective concentration required to produce 50% of the maximal response (EC50). Lower the EC50 = Higher potency.

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12
Q

What is efficacy and how is it related to Emax?

A

The tendency of the drug to activate the receptor is efficacy. Higher Emax = Higher efficacy.

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13
Q

What is quantal graph?

A

It is an all-or-none response (binary). It displays the all-or-none response (efficacy and/or toxicity) to a drug in a population.

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14
Q

How do you determine ED50 from the quantal graph?

A

It is the dose at which 50% of the population has the desired effect.

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15
Q

What is the difference between LD50 and TD50?

A

LD50 is the dose that kills (lethal to) 50% of the population.TD50 is the dose that causes toxic effects in 50% of the population.

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16
Q

What is a therapeutic index?

A

The ratio of a drug’s toxic dose to its therapeutic dose, indicating its safety margin.

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17
Q

How do antagonists affect receptor activity?

A

They bind to receptors and prevent them from activating, blocking the effect of agonists.

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18
Q

How do partial agonists work at receptors?

A

They bind to the receptor and produce a weaker, partial response compared to full agonists.

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19
Q

What is an inverse agonist?

A

A drug that binds to the same part of the receptor as an agonist but induces the opposite effect.

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20
Q

What is the effect of a competitive antagonist on the dose-response curve?

A

The competitive agonist shifts the dose-response curve to the right which means the EC50 the agonist increases.

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21
Q

What is the effect of irreversible antagonist?

A

It reduces the number of available receptors for the agonist to bind. It reduces the Emax.

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22
Q

What are allosteric modulators?

A

Compounds that bind to a receptor at a site other than the agonist binding site and modify the receptor’s response to the agonist.

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23
Q

What is receptor desensitization?

A

A temporary inability of a receptor to respond to a stimulus, often due to repeated or continuous exposure to an agonist.

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24
Q

Explain the concept of pharmacodynamic tolerance.

A

It refers to the body’s reduced response to a drug after prolonged use, requiring increased doses to achieve the same effect.

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25
Q

Explain the concept of intrinsic activity in pharmacology.

A

It is the relative ability of a drug-receptor complex to produce a maximum functional response.

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26
Q

How does receptor overexpression influence drug response?

A

Overexpression can lead to exaggerated responses to drugs, often necessitating dose adjustments.

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27
Q

What is drug affinity?

A

Drug affinity refers to the ability of a drug to bind to its target (receptor).

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28
Q

What is drug efficacy?

A

Drug efficacy refers to the ability of a drug to produce a given response from the target (receptor).

29
Q

List the 4 types of receptor-effector linkages?

A

The 4 types of receptor-effector linkages are ligand-gated ion channels, G protein-couple receptors, kinase-linked receptors and nuclear receptors

30
Q

What is a pharmacophore?

A

Pharmacophore is the active chemical moiety of the drug that binds to the receptor

31
Q

What are the principal mechanisms involved in receptor malfunctions?

A

(1) Autoantibodies directed against receptor proteins and (2) Mutations in gene encoding receptors and proteins involved in signal transduction

32
Q

How will you differentiate competitive and non-competitive antagonists using concentration response curve?

A

Competitive antagonists reduce agonist potency but not agonist maximum effect. Non-competitive antagonists reduce the maximum effect of an agonist, with(out) effects on agonist potency

33
Q

What is an agonist?

A

A substance that binds to a receptor and activates it, producing a physiological response.

34
Q

How do G-protein coupled receptors work?

A

They transmit signals from outside the cell into the cell through interactions with G-proteins.

35
Q

Name a drug that acts on ion channels.

A

Lidocaine, which blocks sodium channels to provide local anaesthesia.

36
Q

What are nuclear receptors and their function?

A

Nuclear receptors are intracellular receptors that, when activated by ligands, function as transcription factors to regulate gene expression.

37
Q

Describe the function of enzyme-linked receptors.

A

They trigger a cascade of biochemical reactions inside the cell after a ligand binds, typically involving phosphorylation.

38
Q

Explain the significance of ligand-gated ion channels.

A

These receptors open or close in response to ligand binding, allowing ions to flow across cell membranes.

39
Q

Define antagonist in pharmacology.

A

A substance that binds to a receptor but does not activate it, blocking or dampening a biological response of an agonist.

40
Q

How do partial agonists work?

A

They bind to and partially stimulate receptors, eliciting a response that is inherently weaker than that of a full agonist.

41
Q

What is an inverse agonist?

A

A drug that binds to the same receptor as an agonist but reduces basal system responses by supressing the spontaneous receptor activity

42
Q

How do allosteric modulators affect drug receptors?

A

They bind to a site other than the active site on the receptor, modifying the receptor’s response to the primary ligand.

43
Q

What role do second messengers play in drug action?

A

They amplify the signal of a first messenger (the ligand), initiating further cellular processes.

44
Q

Differentiate between high and low efficacy drugs.

A

High efficacy drugs can produce a strong response than low efficacy drugs by occupying the same proportion of receptors.

45
Q

What is the therapeutic index?

A

A measure of a drug’s safety margin: the ratio of the dose that causes a toxic effect to the dose that causes a therapeutic effect.

46
Q

Explain drug potency.

A

Drug potency refers to the amount of a drug, expressed as the concentration or dose, required for a given level of effect. More potent drugs require lower doses.

47
Q

How does receptor desensitization occur?

A

It occurs when continuous exposure to a stimulus results in decreased responsiveness of the receptor to the stimulus.

48
Q

What is receptor upregulation?

A

An increase in the number of receptors, often as a compensatory response to chronic receptor inhibition.

49
Q

How does receptor downregulation impact drug effects?

A

It can reduce drug effects by decreasing the number of active receptors available to bind to the drug.

50
Q

What is a biased agonist?

A

A biased agonist preferentially activates certain signalling pathways over others, even when binding to the same receptor.

51
Q

Describe non-competitive antagonism.

A

A form of antagonism where the antagonist reduces the effect of an agonist, without competing for the same binding site.

52
Q

How do competitive antagonists work?

A

They compete with agonists for the same binding site on the receptor, preventing agonist-induced responses.

53
Q

What is pharmacodynamics?

A

The study of the biochemical and physiological effects of drugs and their mechanisms of action.

54
Q

Define pharmacokinetics.

A

The study of how the body absorbs, distributes, metabolizes, and excretes drugs.

55
Q

How do drugs interact with voltage-gated ion channels?

A

They can alter the function of these channels, which are crucial for nerve impulse transmission, by modifying their opening or closing.

56
Q

What is a therapeutic window in pharmacology?

A

Therapeutic window refers to a concentration range bounded at the lower end by the minimum concentration that produces the desired clinical effect and at the upper end, the concentration that produces unacceptable effects or where no further benefit is observed.

57
Q

Explain the significance of drug selectivity.

A

Drug selectivity refers to the ability of a drug to target specific receptors without affecting others, minimizing side effects.

58
Q

Describe the lock and key model of drug-receptor interaction.

A

This model suggests that a drug (key) fits precisely into a receptor (lock) to initiate its effect, mirroring the specificity of enzyme-substrate interactions.

59
Q

What does receptor saturation imply in pharmacodynamics?

A

Receptor saturation occurs when all available receptors are occupied by the drug, typically resulting in the maximal possible response to the drug.

60
Q

How do inverse agonists influence receptor activity?

A

Inverse agonists bind to receptors and stabilize them in an inactive state, reducing their baseline activity.

61
Q

What are allosteric sites on a receptor?

A

Allosteric sites are specific sites on a receptor that, when bound by allosteric modulators, alter the receptor’s activity but are distinct from the primary active site.

62
Q

Explain how receptor polymorphism can affect drug response.

A

Receptor polymorphisms are variations in receptor genes among individuals that can alter receptor function and, consequently, drug efficacy and safety.

63
Q

What is the difference between affinity and intrinsic efficacy in pharmacology?

A

Affinity is how well a drug binds to its receptor, while intrinsic efficacy is the ability of the drug to activate the receptor upon binding.

64
Q

Describe the impact of receptor desensitization on pharmacotherapy.

A

Desensitization reduces the responsiveness of a receptor to its agonist, which can diminish the therapeutic effects of drugs over time.

65
Q

How can drug-receptor interactions lead to side effects?

A

Unintended interactions with non-target receptors can lead to side effects, highlighting the importance of selectivity in drug design.

66
Q

What role do neurotransmitters play in drug-receptor interactions?

A

Neurotransmitters are endogenous chemicals that interact with receptors to regulate bodily functions; drugs can mimic or inhibit these interactions.

67
Q

What is meant by ‘agonist-induced receptor internalization’?

A

This process refers to the endocytosis of receptor-agonist complexes, which can regulate receptor availability and responsiveness.

68
Q

What is the clinical relevance of drug-receptor theory?

A

Understanding drug-receptor interactions is crucial for developing effective and safe pharmacological treatments.

69
Q

How do enzyme inhibitors function as drugs?

A

Enzyme inhibitors block the activity of specific enzymes, thereby altering the biochemical pathways that contribute to disease states.

Master YLL Pharmacology (36 decks)

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