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Pl1002 Integrated Physiology > Pharmakokinetics > Flashcards

Pharmakokinetics Flashcards

1
Q

Which of the following mechanisms of drug transport across cell membranes is energy-dependent?

A) Passive diffusion
B) Facilitated diffusion
C) Active transport
D) Osmosis

A

Answer: C
Explanation: Active transport requires energy to move substances against their concentration gradient, unlike passive and facilitated diffusion.

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2
Q

What factor primarily influences the efficiency of passive drug diffusion across cell membranes?

A) Water solubility
B) Lipid solubility
C) Molecular weight
D) Ionization

A

Answer: B
Explanation: Passive diffusion depends mainly on the lipid solubility of the drug, allowing it to pass through the lipid bilayer of cell membranes.

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2
Q

First-pass metabolism primarily occurs in which organ?

A) Kidney
B) Stomach
C) Liver
D) Lungs

A

Answer: C
Explanation: First-pass metabolism predominantly occurs in the liver, where the drug is metabolized before reaching systemic circulation.

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3
Q

Which of the following does NOT affect drug absorption?

A) Gastric pH
B) Gastric emptying time
C) Plasma protein binding
D) Intestinal motility

A

Answer: C
Explanation: Plasma protein binding affects drug distribution, not absorption.

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4
Q

Which characteristic of a drug leads to a high volume of distribution (Vd)?

A) High plasma protein binding
B) High molecular weight
C) High lipid solubility
D) Low tissue binding

A

Answer: C
Explanation: High lipid solubility leads to extensive tissue distribution, resulting in a high volume of distribution.

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5
Q

What is the approximate volume of distribution for warfarin in a 70 kg adult?

A) 7 liters
B) 16 liters
C) 35 liters
D) 140 liters

A

Answer: A
Explanation: Warfarin has a small volume of distribution, around 7 liters, indicating it primarily remains in the plasma.

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6
Q

Ion trapping of drugs occurs when:

A) A drug is weakly acidic and the environment is basic
B) A drug is weakly basic and the environment is acidic
C) A drug is strongly acidic and the environment is neutral
D) Both A and B

A

Answer: D
Explanation: Ion trapping occurs when a drug is in an environment where it becomes ionized and cannot easily cross cell membranes.

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7
Q

Which phase of drug metabolism involves conjugation reactions?

A) Phase I
B) Phase II
C) Both Phase I and II
D) Neither Phase I nor II

A

Answer: B
Explanation: Phase II metabolism involves conjugation reactions, where a polar molecule is added to the drug.

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8
Q

Cytochrome P450 enzymes are primarily involved in:

A) Phase I oxidative reactions
B) Phase II conjugative reactions
C) Both Phase I and II reactions
D) Excretion of drugs

A

Answer: A
Explanation: Cytochrome P450 enzymes catalyze Phase I oxidative reactions, introducing a functional group to the drug.

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9
Q

Which cytochrome P450 enzyme is predominantly found in the intestinal epithelium?

A) CYP1A2
B) CYP2D6
C) CYP3A4
D) CYP2C9

A

Answer: C
Explanation: CYP3A4 is abundant in the intestinal epithelium and plays a significant role in first-pass metabolism.

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10
Q

Which of the following processes is NOT involved in renal drug excretion?

A) Glomerular filtration
B) Tubular secretion
C) Tubular reabsorption
D) Biliary excretion

A

Answer: D
Explanation: Biliary excretion involves the liver, not the kidneys, which primarily handle glomerular filtration, tubular secretion, and reabsorption.

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11
Q

Which organ is primarily responsible for the excretion of volatile anesthetics?

A) Liver
B) Kidney
C) Lungs
D) Skin

A

Answer: C
Explanation: Volatile anesthetics are mainly excreted through the lungs.

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12
Q

Grapefruit juice is known to inhibit which cytochrome P450 enzyme, leading to increased blood levels of certain drugs?

A) CYP1A2
B) CYP2D6
C) CYP3A4
D) CYP2C9

A

Answer: C
Explanation: Grapefruit juice inhibits CYP3A4, affecting the metabolism of drugs that are substrates of this enzyme.

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13
Q

Which of the following is a consequence of enzyme induction?

A) Decreased drug metabolism
B) Increased drug plasma levels
C) Reduced therapeutic effect of the drug
D) Increased risk of drug toxicity

A

Answer: C
Explanation: Enzyme induction increases the metabolism of drugs, potentially lowering their plasma levels and reducing their therapeutic effect.

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14
Q

What is the primary determinant of the half-life (t1/2) of a drug?

A) Volume of distribution (Vd)
B) Clearance (Cl)
C) Both Vd and Cl
D) Plasma protein binding

A

Answer: C
Explanation: The half-life of a drug is determined by both its volume of distribution and clearance.

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15
Q

A drug with a high clearance rate will:

A) Have a long half-life
B) Accumulate in the body
C) Be rapidly removed from the bloodstream
D) Have high bioavailability

A

Answer: C
Explanation: A high clearance rate means the drug is quickly eliminated from the bloodstream.

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16
Q

Which phase of metabolism is most likely affected by genetic polymorphisms?

A) Phase I
B) Phase II
C) Both Phase I and II
D) Neither Phase I nor II

A

Answer: A
Explanation: Genetic polymorphisms often affect Phase I enzymes like cytochrome P450s, leading to variability in drug metabolism.

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17
Q

In a patient with renal impairment, what adjustment is typically necessary for renally excreted drugs?

A) Increase the dose
B) Decrease the dose
C) No adjustment needed
D) Switch to a different drug

A

Answer: B
Explanation: In renal impairment, the dose of renally excreted drugs often needs to be decreased to prevent toxicity.

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18
Q

Which of the following factors does NOT affect the bioavailability of a drug?

A) First-pass metabolism
B) Drug formulation
C) Plasma protein binding
D) Gastrointestinal pH

A

Answer: C
Explanation: Plasma protein binding affects distribution rather than bioavailability.

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19
Q

The therapeutic index of a drug is:

A) The ratio of its toxic dose to its effective dose
B) The ratio of its absorption rate to its elimination rate
C) The time required to reach peak plasma concentration
D) The proportion of the drug that reaches systemic circulation

A

Answer: A
Explanation: The therapeutic index is a measure of the drug’s safety margin, calculated as the ratio of the toxic dose to the effective dose.

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20
Q

Which of the following drugs is known to have a large volume of distribution?

A) Warfarin
B) Gentamicin
C) Theophylline
D) Digoxin

A

Answer: D
Explanation: Digoxin has a large volume of distribution, indicating extensive tissue binding.

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21
Q

Which process is primarily responsible for the renal excretion of highly protein-bound drugs?

A) Glomerular filtration
B) Tubular secretion
C) Tubular reabsorption
D) Biliary excretion

A

Answer: B
Explanation: Highly protein-bound drugs are not efficiently filtered by the glomerulus and rely more on tubular secretion for renal excretion.

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22
Q

Which of the following can decrease the oral bioavailability of a drug?

A) Increased gastric pH
B) Decreased gastric emptying time
C) Increased hepatic first-pass metabolism
D) Decreased intestinal motility

A

Answer: C
Explanation: Increased hepatic first-pass metabolism reduces the amount of drug reaching systemic circulation, thereby decreasing oral bioavailability.

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23
Q

In which situation would a drug’s half-life be prolonged?

A) Increased clearance
B) Decreased volume of distribution
C) Decreased clearance
D) Increased hepatic metabolism

A

Answer: C
Explanation: Decreased clearance results in a prolonged half-life, as the drug is removed from the body more slowly.

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24
Q

What does the term ‘bioequivalence’ refer to?

A) Similar therapeutic effects of two drugs
B) Similar bioavailability of two drug formulations
C) Identical chemical structure of two drugs
D) Same route of administration for two drugs

A

Answer: B
Explanation: Bioequivalence means that two drug formulations have similar bioavailability and produce the same effect at the site of physiological activity.

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25
Q

Which factor can lead to drug accumulation in the body?

A) High clearance
B) Long dosing interval
C) Slow absorption rate
D) Long half-life

A

Answer: D
Explanation: A long half-life can lead to drug accumulation, especially if the dosing interval is shorter than the half-life.

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26
Q

Which of the following statements about facilitated diffusion is TRUE?

A) It requires energy expenditure.
B) It is a form of active transport.
C) It requires a carrier protein.
D) It moves substances against their concentration gradient.

A

Answer: C
Explanation: Facilitated diffusion requires a carrier protein to move substances across cell membranes but does not require energy.

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27
Q

What is the primary site of action for cytochrome P450 enzymes?

A) Kidney
B) Intestine
C) Liver
D) Lungs

A

Answer: C
Explanation: Cytochrome P450 enzymes are primarily located in the liver, where they metabolize drugs.

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28
Q

What is the effect of competitive inhibition on enzyme activity?

A) Decreases the enzyme’s maximum velocity (Vmax)
B) Increases the enzyme’s affinity for the substrate
C) Increases the enzyme’s maximum velocity (Vmax)
D) Decreases the enzyme’s affinity for the substrate

A

Answer: A
Explanation: Competitive inhibitors decrease the enzyme’s maximum velocity (Vmax) by competing with the substrate for the active site.

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29
Q

Which of the following drugs is a known substrate for CYP2D6?

A) Warfarin
B) Theophylline
C) Risperidone
D) Omeprazole

A

Answer: C
Explanation: Risperidone is metabolized by CYP2D6.

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30
Q

A drug with high first-pass metabolism will have:

A) High oral bioavailability
B) Low oral bioavailability
C) High plasma protein binding
D) Low plasma protein binding

A

Answer: B
Explanation: Drugs with high first-pass metabolism have low oral bioavailability because a significant portion is metabolized before reaching systemic circulation.

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31
Q

The bioavailability of a drug administered intravenously is:

A) 50%
B) 75%
C) 90%
D) 100%

A

Answer: D
Explanation: Intravenous administration ensures 100% bioavailability, as the drug is directly introduced into systemic circulation.

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32
Q

Which factor does NOT significantly affect drug distribution?

A) Blood flow to tissues
B) Drug solubility
C) Drug metabolism
D) Plasma protein binding

A

Answer: C
Explanation: Drug metabolism primarily affects drug clearance, not distribution.

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33
Q

In patients with liver disease, doses of drugs primarily metabolized by the liver should be:

A) Increased
B) Decreased
C) Unchanged
D) Given intravenously

A

Answer: B
Explanation: In liver disease, the metabolism of drugs is impaired, so doses should be decreased to avoid toxicity.

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34
Q

Which of the following is a characteristic of zero-order kinetics?

A) Rate of elimination is constant
B) Rate of elimination is proportional to drug concentration
C) Half-life remains constant
D) Clearance is constant

A

Answer: A
Explanation: In zero-order kinetics, the rate of elimination is constant regardless of drug concentration.

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35
Q

A drug with a small volume of distribution is likely to be:

A) Lipid-soluble
B) Highly protein-bound
C) Extensively distributed in tissues
D) Rapidly metabolized

A

Answer: B
Explanation: A small volume of distribution indicates that the drug remains primarily in the plasma, often due to high protein binding.

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36
Q

Which process is most affected by a drug’s pKa value?

A) Absorption
B) Distribution
C) Metabolism
D) Excretion

A

Answer: A
Explanation: A drug’s pKa affects its ionization, which in turn influences its absorption across biological membranes.

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37
Q

The main purpose of Phase II metabolism is to:

A) Introduce a functional group
B) Increase lipid solubility
C) Make the drug more water-soluble
D) Increase bioavailability

A

Answer: C
Explanation: Phase II metabolism involves conjugation reactions that make the drug more water-soluble and amenable to renal excretion.

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38
Q

Which enzyme is most likely to be involved in the oxidative metabolism of drugs?

A) Amylase
B) Lipase
C) Cytochrome P450
D) Protease

A

Answer: C
Explanation: Cytochrome P450 enzymes are key players in the oxidative metabolism of drugs.

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39
Q

The first-pass effect is most significant for drugs administered:

A) Intravenously
B) Orally
C) Subcutaneously
D) Intramuscularly

A

Answer: B
Explanation: The first-pass effect primarily affects orally administered drugs, as they pass through the liver before reaching systemic circulation.

40
Q

Which of the following is true about enzyme induction?

A) It decreases drug metabolism
B) It increases the plasma concentration of drugs
C) It can be beneficial in some therapeutic contexts
D) It is usually harmful and should be avoided

A

Answer: C
Explanation: Enzyme induction can be beneficial, such as in the case of treating neonatal jaundice by inducing enzymes to conjugate bilirubin.

41
Q

Which factor is least likely to affect drug metabolism?

A) Age
B) Genetic polymorphisms
C) Route of administration
D) Diet

A

Answer: C
Explanation: Route of administration primarily affects drug absorption rather than metabolism.

42
Q

Which of the following describes a drug with low bioavailability?

A) It is extensively metabolized before reaching systemic circulation
B) It has high plasma protein binding
C) It is rapidly excreted by the kidneys
D) It has a long half-life

A

Answer: A
Explanation: Low bioavailability often results from extensive first-pass metabolism.

43
Q

Which organ is most important for the excretion of drugs and their metabolites?

A) Liver
B) Kidneys
C) Lungs
D) Skin

A

Answer: B
Explanation: The kidneys play a crucial role in the excretion of drugs and their metabolites.

44
Q

Which of the following statements about Phase I and Phase II reactions is correct?

A) Phase I reactions always occur before Phase II reactions
B) Phase II reactions involve oxidation and reduction
C) Phase I reactions introduce functional groups to the drug
D) Phase II reactions decrease the water solubility of drugs

A

Answer: C
Explanation: Phase I reactions introduce or expose functional groups on the drug molecule, often preparing it for subsequent Phase II conjugation.

45
Q

Which drug is known for its non-linear (zero-order) kinetics at therapeutic doses?

A) Aspirin
B) Phenytoin
C) Theophylline
D) Warfarin

A

Answer: B
Explanation: Phenytoin exhibits zero-order kinetics at therapeutic doses, where its metabolism becomes saturated.

46
Q

Which factor does NOT typically influence renal drug excretion?

A) Plasma protein binding
B) Glomerular filtration rate
C) Tubular secretion
D) Hepatic metabolism

A

Answer: D
Explanation: Hepatic metabolism affects drug clearance, but not directly renal excretion, which depends on filtration, secretion, and reabsorption.

46
Q

In pharmacokinetics, ‘clearance’ refers to:

A) The rate of drug absorption
B) The volume of plasma cleared of drug per unit time
C) The time it takes for half of the drug to be eliminated
D) The rate of drug distribution to tissues

A

Answer: B
Explanation: Clearance is a measure of the volume of plasma from which the drug is completely removed per unit time.

47
Q

Which of the following is a common consequence of enzyme inhibition?

A) Decreased drug plasma levels
B) Increased drug plasma levels
C) Decreased therapeutic effects
D) Increased drug excretion

A

Answer: B
Explanation: Enzyme inhibition reduces the metabolism of the drug, leading to increased plasma levels.

48
Q

Which of the following routes of administration bypasses the first-pass effect?

A) Oral
B) Rectal
C) Sublingual
D) Inhalation

A

Answer: C
Explanation: Sublingual administration allows drugs to be absorbed directly into the systemic circulation, bypassing the liver.

49
Q

The term ‘therapeutic window’ refers to:

A) The time it takes for a drug to reach peak concentration
B) The dosage range between the minimum effective concentration and the minimum toxic concentration
C) The duration of drug action
D) The rate of drug absorption

A

Answer: B
Explanation: The therapeutic window is the range of drug doses that produce a therapeutic effect without causing significant adverse effects.

50
Q

Which of the following is an example of a Phase II metabolic reaction?

A) Oxidation
B) Reduction
C) Hydrolysis
D) Glucuronidation

A

Answer: D
Explanation: Glucuronidation is a Phase II conjugation reaction that makes drugs more water-soluble for excretion.

51
Q

Which of the following best describes the role of plasma protein binding in drug distribution?

A) It increases the drug’s therapeutic effect
B) It decreases the drug’s half-life
C) It limits the free drug available for distribution
D) It enhances drug excretion

A

Answer: C
Explanation: Plasma protein binding limits the amount of free drug available to distribute to tissues and exert its effects.

52
Q

Which drug characteristic is most likely to result in a prolonged duration of action?

A) High clearance
B) Low volume of distribution
C) High lipid solubility
D) High plasma protein binding

A

Answer: C
Explanation: High lipid solubility allows drugs to be stored in body fat and released slowly, prolonging their duration of action.

53
Q

What is the main purpose of Phase I metabolic reactions?

A) To conjugate drugs with polar molecules
B) To increase drug solubility
C) To introduce or expose functional groups
D) To facilitate renal excretion

A

Answer: C
Explanation: Phase I reactions introduce or expose functional groups on the drug molecule, preparing it for further metabolism or excretion.

54
Q

Which factor primarily determines the volume of distribution (Vd) of a drug?

A) The rate of drug metabolism
B) The rate of drug absorption
C) The extent of drug binding to plasma proteins and tissues
D) The rate of drug excretion

A

Answer: C
Explanation: The volume of distribution is determined by how extensively a drug binds to plasma proteins and tissues.

55
Q

Which of the following is a likely consequence of drug interaction involving enzyme inhibition?

A) Decreased half-life of the inhibited drug
B) Increased therapeutic effect of the inhibited drug
C) Decreased plasma concentration of the inhibited drug
D) Increased clearance of the inhibited drug

A

Answer: B
Explanation: Enzyme inhibition can lead to increased plasma concentration and therapeutic effect of the inhibited drug.

56
Q

Which of the following pharmacokinetic parameters is most affected by renal function?

A) Absorption
B) Distribution
C) Metabolism
D) Excretion

A

Answer: D
Explanation: Renal function primarily affects drug excretion, influencing the clearance and half-life of renally excreted drugs.

57
Q

Which type of drug interaction involves one drug altering the rate of metabolism of another drug?

A) Pharmacokinetic interaction
B) Pharmacodynamic interaction
C) Synergistic interaction
D) Antagonistic interaction

A

Answer: A
Explanation: Pharmacokinetic interactions involve changes in drug absorption, distribution, metabolism, or excretion, such as one drug altering the metabolism rate of another.

58
Q

Which of the following factors can lead to decreased drug absorption?

A) Increased gastric emptying time
B) High lipid solubility
C) Increased intestinal motility
D) High drug concentration

A

Answer: C
Explanation: Increased intestinal motility can decrease the time available for drug absorption, reducing its bioavailability.

59
Q

Which enzyme is responsible for the majority of Phase I drug metabolism?

A) Acetylcholinesterase
B) Cytochrome P450
C) Pepsin
D) Trypsin

A

Answer: B
Explanation: Cytochrome P450 enzymes are responsible for the majority of Phase I oxidative metabolism reactions.

60
Q

Which of the following best describes the enterohepatic circulation of drugs?

A) Drugs are absorbed in the intestines and directly enter systemic circulation
B) Drugs are secreted into bile, reabsorbed in the intestines, and returned to the liver
C) Drugs bypass the liver and are excreted unchanged
D) Drugs are metabolized in the liver and excreted in the urine

A

Answer: B
Explanation: Enterohepatic circulation involves drugs being secreted into bile, reabsorbed in the intestines, and returned to the liver for further metabolism.

61
Q

Which of the following statements about drug excretion is TRUE?

A) Lipid-soluble drugs are readily excreted by the kidneys
B) Ionized drugs are more likely to be reabsorbed in the renal tubules
C) The liver is the primary organ for drug excretion
D) Active transport can contribute to renal drug excretion

A

Answer: D
Explanation: Active transport mechanisms in the renal tubules can facilitate the excretion of drugs.

62
Q

Which of the following factors does NOT significantly influence drug metabolism?

A) Genetic polymorphisms
B) Enzyme inhibition
C) Drug ionization
D) Enzyme induction

A

Answer: C
Explanation: Drug ionization primarily affects absorption and distribution rather than metabolism.

63
Q

A drug with a high volume of distribution is most likely to:

A) Be confined to the plasma compartment
B) Be extensively distributed in body tissues
C) Have a short half-life
D) Have a high rate of renal excretion

A

Answer: B
Explanation: A high volume of distribution indicates that the drug is extensively distributed in body tissues.

64
Q

Which of the following best describes a pharmacodynamic drug interaction?

A) One drug alters the absorption of another drug
B) One drug changes the effect of another drug without altering its concentration
C) One drug accelerates the metabolism of another drug
D) One drug increases the renal excretion of another drug

A

Answer: B
Explanation: Pharmacodynamic interactions occur when one drug alters the effect of another drug without changing its concentration in the blood.

65
Q

Which type of reaction is characteristic of Phase I metabolism?

A) Conjugation
B) Reduction
C) Hydrolysis
D) Sulfation

A

Answer: B
Explanation: Reduction is a common reaction in Phase I metabolism, along with oxidation and hydrolysis.

66
Q

Which of the following factors is least likely to affect drug distribution?

A) Blood flow to tissues
B) Drug solubility
C) Drug ionization
D) Drug metabolism

A

Answer: D
Explanation: Drug metabolism affects drug clearance, whereas distribution is influenced by factors such as blood flow, solubility, and ionization.

67
Q

The primary site of drug metabolism in the body is:

A) Kidneys
B) Liver
C) Intestines
D) Lungs

A

Answer: B
Explanation: The liver is the primary site of drug metabolism, housing various metabolic enzymes, including cytochrome P450.

68
Q

Which of the following is a characteristic of facilitated diffusion?

A) It requires energy
B) It moves substances against their concentration gradient
C) It uses carrier proteins
D) It involves the direct passage of substances through the lipid bilayer

A

Answer: C
Explanation: Facilitated diffusion uses carrier proteins to transport substances across cell membranes without requiring energy.

69
Q

Which of the following statements about drug clearance is TRUE?

A) It is directly proportional to the volume of distribution
B) It is the same for all drugs
C) It can be affected by renal and hepatic function
D) It is independent of blood flow

A

Answer: C
Explanation: Drug clearance can be significantly affected by both renal and hepatic function, which are crucial for drug elimination.

70
Q

Which of the following is NOT a mechanism of drug excretion?

A) Glomerular filtration
B) Tubular reabsorption
C) Biliary excretion
D) First-pass metabolism

A

Answer: D
Explanation: First-pass metabolism is a process that affects drug bioavailability and occurs before the drug reaches systemic circulation, not an excretion mechanism.

71
Q

Which of the following drugs is known to have a low volume of distribution?

A) Warfarin
B) Digoxin
C) Quinacrine
D) Mianserin

A

Answer: A
Explanation: Warfarin has a low volume of distribution, indicating it remains primarily in the plasma and has limited tissue distribution.

72
Q

Which of the following factors can increase the bioavailability of an orally administered drug?

A) High first-pass metabolism
B) Low gastric pH
C) Rapid gastric emptying
D) Slow intestinal motility

A

Answer: D
Explanation: Slow intestinal motility allows more time for the drug to be absorbed, increasing its bioavailability.

73
Q

Which of the following is a feature of zero-order kinetics?

A) The rate of drug elimination is constant
B) The rate of drug elimination is proportional to drug concentration
C) The half-life of the drug is constant
D) The clearance of the drug is constant

A

Answer: A
Explanation: In zero-order kinetics, the rate of drug elimination is constant regardless of the drug concentration.

74
Q

Which enzyme is most likely to be inhibited by grapefruit juice?

A) CYP1A2
B) CYP2D6
C) CYP2C9
D) CYP3A4

A

Answer: D
Explanation: Grapefruit juice is known to inhibit CYP3A4, affecting the metabolism of many drugs.

75
Q

Which of the following statements about renal drug excretion is TRUE?

A) Only lipid-soluble drugs are excreted by the kidneys
B) Protein-bound drugs are freely filtered at the glomerulus
C) Ionized drugs are more likely to be excreted than reabsorbed
D) Tubular secretion does not require energy

A

Answer: C
Explanation: Ionized drugs are less likely to be reabsorbed in the renal tubules and more likely to be excreted.

76
Q

Which factor is most important for drug distribution to the brain?

A) Molecular weight of the drug
B) Ionization of the drug
C) Lipid solubility of the drug
D) Plasma protein binding of the drug

A

Answer: C
Explanation: The blood-brain barrier is highly selective, and lipid solubility is a key factor for drug distribution to the brain.

77
Q

Which of the following best describes the therapeutic index of a drug?

A) The dosage range that produces therapeutic effects without toxicity
B) The ratio of the maximum safe dose to the minimum effective dose
C) The time it takes for the drug to reach its peak concentration
D) The difference between the toxic and therapeutic concentrations

A

Answer: D
Explanation: The therapeutic index is the ratio of the toxic dose to the effective dose, providing a measure of drug safety.

78
Q

Which of the following drugs is most likely to be affected by genetic polymorphisms in metabolic enzymes?

A) Acetaminophen
B) Warfarin
C) Aspirin
D) Metformin

A

Answer: B
Explanation: Warfarin metabolism is significantly affected by genetic polymorphisms in CYP2C9 and VKORC1.

79
Q

Which of the following is an example of a prodrug?

A) Codeine
B) Morphine
C) Ibuprofen
D) Acetaminophen

A

Answer: A
Explanation: Codeine is a prodrug that is metabolized to morphine, its active form.

80
Q

Which type of drug interaction involves the displacement of one drug from plasma protein binding sites by another drug?

A) Pharmacokinetic interaction
B) Pharmacodynamic interaction
C) Synergistic interaction
D) Antagonistic interaction

A

Answer: A
Explanation: Displacement interactions are pharmacokinetic, affecting the distribution of drugs.

81
Q

Which of the following best describes the relationship between enzyme induction and drug metabolism?

A) Enzyme induction increases drug metabolism
B) Enzyme induction decreases drug metabolism
C) Enzyme induction has no effect on drug metabolism
D) Enzyme induction reduces the number of enzymes available

A

Answer: A
Explanation: Enzyme induction increases the activity of metabolic enzymes, leading to increased drug metabolism.

82
Q

Which factor does NOT typically affect the absorption of a drug?

A) Drug solubility
B) Blood flow to the absorption site
C) Drug metabolism
D) pH of the absorption site

A

Answer: C
Explanation: Drug metabolism affects the clearance and bioavailability, not the absorption directly.

83
Q

Which of the following best describes the term ‘bioequivalence’?

A) Two drugs have identical therapeutic effects
B) Two drug formulations have similar bioavailability and produce the same effect
C) Two drugs have the same chemical structure
D) Two drugs are administered via the same route

A

Answer: B
Explanation: Bioequivalence means that two drug formulations have similar bioavailability and produce the same clinical effect.

84
Q

Which of the following is NOT a consequence of drug metabolism?

A) Activation of prodrugs
B) Detoxification of harmful substances
C) Increased water solubility of drugs
D) Increased lipid solubility of drugs

A

Answer: D
Explanation: Drug metabolism typically increases water solubility to facilitate excretion, not lipid solubility.

85
Q

Which of the following drugs is most likely to be excreted unchanged in the urine?

A) Warfarin
B) Penicillin
C) Diazepam
D) Aspirin

A

Answer: B
Explanation: Penicillin is primarily excreted unchanged in the urine.

86
Q

Which of the following factors can decrease the bioavailability of a drug?

A) High lipid solubility
B) Rapid gastric emptying
C) High first-pass metabolism
D) Low molecular weight

A

Answer: C
Explanation: High first-pass metabolism significantly reduces the amount of drug that reaches systemic circulation, decreasing bioavailability.

87
Q

Which of the following is a likely result of enzyme inhibition?

A) Increased drug clearance
B) Decreased drug half-life
C) Increased drug plasma levels
D) Decreased drug absorption

A

Answer: C
Explanation: Enzyme inhibition decreases the metabolism of drugs, leading to increased plasma levels.

88
Q

Which of the following statements about drug bioavailability is TRUE?

A) It is highest for orally administered drugs
B) It is unaffected by the drug’s formulation
C) It can be influenced by the route of administration
D) It is the same for all drugs

A

Answer: C
Explanation: Bioavailability can vary significantly with the route of administration, with intravenous administration typically having 100% bioavailability.

89
Q

Which of the following factors can increase the volume of distribution (Vd) of a drug?

A) High plasma protein binding
B) High lipid solubility
C) High molecular weight
D) High clearance

A

Answer: B
Explanation: High lipid solubility allows a drug to distribute more extensively into tissues, increasing its volume of distribution.

90
Q

Which of the following is an example of a pharmacokinetic drug interaction?

A) One drug enhances the effect of another drug
B) One drug alters the metabolism of another drug
C) One drug blocks the receptor of another drug
D) One drug competes for the same binding site as another drug

A

Answer: B
Explanation: Pharmacokinetic interactions involve changes in absorption, distribution, metabolism, or excretion, such as one drug altering the metabolism of another.

91
Q

Which of the following is a characteristic of first-order kinetics?

A) The rate of drug elimination is constant
B) The rate of drug elimination is proportional to drug concentration
C) The half-life of the drug changes with concentration
D) The clearance of the drug changes with concentration

A

Answer: B
Explanation: In first-order kinetics, the rate of drug elimination is proportional to the drug concentration.

92
Q

Which of the following factors can lead to drug accumulation in the body?

A) High clearance
B) Short half-life
C) Long dosing interval
D) Low therapeutic index

A

Answer: D
Explanation: A low therapeutic index means the drug’s effective dose is close to its toxic dose, which can lead to accumulation if not properly monitored.

93
Q

Which of the following is a common route of drug excretion?

A) Metabolism
B) Filtration
C) Secretion
D) Reabsorption

A

Answer: B
Explanation: Filtration in the kidneys is a primary route of drug excretion.

94
Q

Which of the following is true about drugs with a high therapeutic index?

A) They have a narrow margin of safety
B) They are more likely to cause toxicity at therapeutic doses
C) They require close monitoring of blood levels
D) They have a wide margin of safety

A

Answer: D
Explanation: Drugs with a high therapeutic index have a wide margin of safety, meaning the effective dose is far from the toxic dose.

95
Q

Which of the following can decrease the half-life of a drug?

A) Enzyme induction
B) Enzyme inhibition
C) Increased plasma protein binding
D) Decreased renal function

A

Answer: A
Explanation: Enzyme induction increases the metabolism of the drug, leading to a decreased half-life.

96
Q

Which of the following is a characteristic of drugs that undergo extensive first-pass metabolism?

A) High oral bioavailability
B) Low oral bioavailability
C) Long half-life
D) High therapeutic index

A

Answer: B
Explanation: Extensive first-pass metabolism reduces the amount of drug reaching systemic circulation, resulting in low oral bioavailability.

97
Q

Which of the following is a potential consequence of drug-drug interactions involving cytochrome P450 enzymes?
- A) Increased drug absorption
- B) Decreased drug metabolism
- C) Decreased drug distribution
- D) Increased drug excretion

A
  • Answer: B
  • Explanation: Drug-drug interactions involving cytochrome P450 enzymes can lead to decreased metabolism of one or both drugs, affecting their plasma levels and effects.

Pl1002 Integrated Physiology (7 decks)

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