Pharmacokinetics & Dynamics Review
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Questions and Answers

What is the most important mechanism for drug absorption across the placenta?

  • Facilitated diffusion
  • Endocytosis
  • Active transport
  • Passive diffusion (correct)

    • Which factor decreases free drug concentration in fetal circulation?

  • Increased body fat
  • Increased protein binding (correct)
  • Lower body water content
  • Higher cardiac output

    • The metabolism of some drugs in the fetus operates at what capacity compared to adult levels?

  • Completely inactive
  • Always higher than adults
  • Functionally at adult levels (correct)
  • Always lower than adults

    • What occurs during the elimination phase of pharmacokinetics in fetuses?

    <p>Renal excretion into amniotic fluid (B)</p> Signup and view all the answers

    Which of the following statements regarding first-pass metabolism is correct?

    <p>Intravenous drugs do not undergo first-pass metabolism (C)</p> Signup and view all the answers

    Which of the following could increase drug delivery to the fetal brain?

    <p>Increased maternal cardiac output (C)</p> Signup and view all the answers

    Ion trapping in amniotic fluid refers to which of the following?

    <p>Concentration of water-soluble drugs in amniotic fluid (B)</p> Signup and view all the answers

    Which of the following best describes the physiological change affecting drug metabolism in fetuses experiencing hypoxia?

    <p>Decreased clearance results in greater drug accumulation (D)</p> Signup and view all the answers

    Which channels open as a delayed response causing the membrane potential to become more negative?

    <p>Voltage-gated potassium channels (D)</p> Signup and view all the answers

    What process returns the neuron back to its resting membrane potential?

    <p>Active transport of ions by the sodium-potassium pump (B)</p> Signup and view all the answers

    What is the term for the delay between peak plasma concentration and peak central nervous system concentration?

    <p>Hysteresis (B)</p> Signup and view all the answers

    Which anesthetic achieves rapid equilibration between plasma and effect site?

    <p>Thiopental (A)</p> Signup and view all the answers

    What describes the term 'ke0' in effect-site elimination?

    <p>Rate constant of drug elimination from the effect site (B)</p> Signup and view all the answers

    What generally affects the time to peak effect site concentration?

    <p>Size of intravenous bolus dose (D)</p> Signup and view all the answers

    Which statement is true regarding the mechanisms of drug clearance?

    <p>Hepatic metabolism and renal excretion are crucial for drug clearance. (B)</p> Signup and view all the answers

    How is the time to reach 50% of plasma concentration defined mathematically?

    <p>T 1/2 ke0 (A)</p> Signup and view all the answers

    Which anesthetics are characterized by slow equilibration between plasma and effect site?

    <p>Morphine and ketorolac (A)</p> Signup and view all the answers

    What is the relationship between a drug's half-life and dosing interval?

    <p>Dosing interval is indirectly related to half-life. (A)</p> Signup and view all the answers

    Which of the following best describes Phase II reactions in drug metabolism?

    <p>They involve conjugation to increase water solubility. (C)</p> Signup and view all the answers

    Which factor does NOT directly affect the extraction capacity of a drug?

    <p>The volume of distribution of the drug. (B)</p> Signup and view all the answers

    Which of these processes is associated with the termination of drug action?

    <p>Distribution of the drug out of circulation. (C)</p> Signup and view all the answers

    When considering the neuronal action potential, what is the first action that occurs?

    <p>Voltage-gated sodium channels open. (A)</p> Signup and view all the answers

    What factor primarily affects the spontaneous chemical reactions involved in drug metabolism?

    <p>Temperature and environmental conditions. (B)</p> Signup and view all the answers

    Which of the following is NOT a typical outcome of drug metabolism?

    <p>Enhanced pharmacologic action of the parent drug. (A)</p> Signup and view all the answers

    Which of the following statements about ionized drugs is true?

    <p>Nonionized drugs are more lipophilic. (B)</p> Signup and view all the answers

    Which of the following is NOT a characteristic of unionized drugs?

    <p>Hydrophilic (C)</p> Signup and view all the answers

    At pH 2.5, is aspirin primarily in a lipid-soluble form?

    <p>TRUE (D)</p> Signup and view all the answers

    At pH 7.4, how does the ionization of the basic drug promethazine (pKa 9.1) compare to its ionization at pH 2?

    <p>More ionized at pH 7.4 (B)</p> Signup and view all the answers

    Is absorption of a weakly basic drug likely to occur faster from the stomach than from the intestine?

    <p>FALSE (A)</p> Signup and view all the answers

    Does acidification of the urine accelerate the secretion of a weak base with a pKa of 8?

    <p>TRUE (D)</p> Signup and view all the answers

    What term describes the process when a ligand binds to a receptor and enhances cellular response?

    <p>Amplification (D)</p> Signup and view all the answers

    Which statement regarding the distribution of drugs to specific tissues is false?

    <p>Drugs that are strongly bound to plasma proteins have increased distribution. (D)</p> Signup and view all the answers

    What is characterized as the amount of a drug divided by the desired plasma concentration?

    <p>Volume of distribution (D)</p> Signup and view all the answers

    What is the role of an intracellular chemical messenger following receptor activation?

    <p>Relay (D)</p> Signup and view all the answers

    What is the immediate consequence of activating a G-protein coupled receptor?

    <p>Conformational change (D)</p> Signup and view all the answers

    Which neurotransmitter-receptor complex is considered inhibitory?

    <p>GABA receptor (A)</p> Signup and view all the answers

    What term refers to the maximum response a drug can produce, regardless of the dose given?

    <p>Max efficacy (A)</p> Signup and view all the answers

    What can be inferred if drug X is significantly more effective than drug Y at lower dosages?

    <p>Drug X is about 100 times more potent than drug Y. (A), Drug Y is less efficacious than drug X. (C)</p> Signup and view all the answers

    What describes a drug that acts as a full receptor activator?

    <p>Full agonist (C)</p> Signup and view all the answers

    What is the therapeutic index primarily a measure of?

    <p>Safety margin of the drug (A)</p> Signup and view all the answers

    Study Notes

    Pharmacokinetics & Dynamics Review

    • Pharmacokinetics is the study of how the body processes drugs.
    • This includes absorption, distribution, metabolism, and elimination.

    Spotlight on Fetal Pharmacokinetics

    • Absorption:
      • The placenta is the primary absorption route.
      • Passive diffusion is the primary mechanism.
      • Anesthetics, opioids, benzodiazepines quickly cross the placenta.
      • Neuromuscular blockers cross slowly.
    • Distribution:
      • Increased delivery to the fetal brain, related to cardiac output.
      • Decreased protein binding increases free drug concentration.
      • Lower body fat and higher body water can affect distribution.
      • Ion trapping in amniotic fluid serves as a reservoir for water-soluble drugs.
    • Metabolism:
      • Fetal enzyme function may be at adult levels, or less active with delayed metabolism (e.g., opiates, NSAIDs, local anesthetics).
      • Drug clearance is decreased in hypoxia.
    • Elimination:
      • Fetal renal excretion into amniotic fluid.
      • Drug transfer to the mother via umbilical vessels and placenta.
      • Drug recirculation via amniotic fluid re-ingestion is possible.

    Questions & Answers

    • Question #1: Drugs taken orally most likely follow the sequence Gut > liver > vein > heart > lung > heart > artery. (C)

    • Question #2: Intravenous drugs do not undergo first pass hepatic metabolism. (B)

    • Question #3: Match drug routes (PO, IV, inhalation) to their corresponding absorption/distribution curves. Relevant information on slide.

    • Question #4: Nonionized drugs are more lipophilic. (C)

    • Question #5: Hydrophilic is NOT a characteristic of unionized drugs. (B)

    • Question #6: BH+ readily crosses the placenta. (A)

    • Question #7: Aspirin (acetylsalicylic acid, pKa 3.5) is primarily in a lipid-soluble form at pH 2.5. (A)

    • Question #8: Promethazine (pKa 9.1) is more ionized at pH 7.4 than at pH 2. (A)

    • Question #9: Absorption of a weakly basic drug is faster from the stomach than the intestine. (A)

    • Question #10: Acidification of the urine accelerates the secretion of a weak base (pKa 8). (A)

    • Question #11: Uncharged molecules readily cross cell membranes. (A)

    • Question #12: Distribution of drugs to tissues depends on the unbound drug concentration gradient between plasma and tissues. (C)

    • Question #13: Drugs must be excreted to terminate drug action. (A)

    • Question #14: Ligand binding to a receptor to increase cellular response is known as amplification. (A)

    • Question #15: Receptor activation causes another intracellular chemical messenger to cause a cellular or tissue response. This is known as Relay. (C)

    • Question #16: Conformational change happens when receptor is activated immediately. (D)

    • Question #17: Drug X is 100 times more potent than Drug Y. (B)

    • Question #18: Partial competitive agonist. (C)

    • Question #19: Max efficacy. (B)

    Additional Concepts

    • Volume of distribution: The theoretical volume of fluid required to contain the drug if it were uniformly distributed at the same concentration as in plasma.
    • Water vs. Lipid solubility: Lipid-soluble drugs distribute more extensively than water-soluble drugs.
    • Matching: Review the provided matching key for specific definitions.

    Other Topics Mentioned

    • Pharmacodynamics: Study of how drugs affect the body (i.e., dose, activity, mechanisms).
    • Neuron Action Potential: (depolarization by Na, repolarization by K) & Na-K pumps
    • Hotspot Matching of Nervous System Components: Review diagram.
    • Biophase & Anesthetics: Relevant information related to effects and action.

    Further Study Points

    • Review the provided diagrams and figures/tables related to these concepts.

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    Description

    This quiz focuses on the essential principles of pharmacokinetics and pharmacodynamics, particularly how drugs are absorbed, distributed, metabolized, and eliminated by the body. Special attention is given to fetal pharmacokinetics, examining unique factors that influence drug interactions during pregnancy. Test your knowledge on these critical concepts in drug therapy.

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