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Questions and Answers

What is the primary focus of pharmaco-dynamics?

  • The study of the biochemical and physiological effects of xenobiotics on living systems (correct)
  • The study of the routes of drug administration and their effects on the body
  • The study of the biological, physical, and chemical processes that determine how drugs are absorbed and distributed in the human body
  • The study of the biological, chemical, and physical processes that determine how drugs are metabolized and/or excreted from the body
  • What is the term for the study of the biological, physical, and chemical processes that are responsible for changes observed in xenobiotic concentration in the blood over time following administration?

  • Pharmaco-therapeutics
  • Pharmaco-genomics
  • Pharmaco-kinetics (correct)
  • Pharmaco-dynamics
  • What is the term for the study of the biochemical and physiological effects of xenobiotics on living systems?

  • Pharmaco-kinetics
  • Pharmaco-dynamics (correct)
  • Pharmaco-genomics
  • Pharmaco-therapeutics
  • What is bioavailability?

    <p>The extent to which a drug is absorbed into the bloodstream</p> Signup and view all the answers

    What is the volume of distribution?

    <p>The extent to which a drug is distributed throughout the body</p> Signup and view all the answers

    What is drug clearance?

    <p>The rate at which a drug is eliminated from the body</p> Signup and view all the answers

    What is the process by which a drug is eliminated from the body?

    <p>Excretion</p> Signup and view all the answers

    What do the initials 'ADME' stand for?

    <p>Absorption, Distribution, Metabolism, Elimination</p> Signup and view all the answers

    What is the primary factor that influences the absorption of xenobiotics into the body?

    <p>Lipid partition coefficient</p> Signup and view all the answers

    Drugs with higher lipid partition coefficients are more likely to accumulate in which phase?

    <p>Octanol phase</p> Signup and view all the answers

    What is the reason why drugs with higher lipid partition coefficients can cross biological membranes more efficiently?

    <p>They have enhanced solubility in the plasma membrane</p> Signup and view all the answers

    What is the process by which xenobiotics gain entry into the body?

    <p>Absorption</p> Signup and view all the answers

    Which of the following is NOT a phase of excretion?

    <p>Absorption</p> Signup and view all the answers

    What is the cell membrane chemically similar to?

    <p>Octanol phase</p> Signup and view all the answers

    What is the purpose of agitating and equilibrating the octanol and water phases?

    <p>To measure the lipid partition coefficient</p> Signup and view all the answers

    What is the characteristic of drugs that are able to cross biological membranes?

    <p>They are able to partition between aqueous and organic phases</p> Signup and view all the answers

    What is the primary characteristic of passive diffusion across membranes?

    <p>It is driven by concentration gradient and favors small, uncharged molecules</p> Signup and view all the answers

    Which of the following statements is true about facilitated diffusion?

    <p>It is an energy-independent process driven by concentration gradient</p> Signup and view all the answers

    What is the primary difference between carrier-mediated and non-carrier mediated transport?

    <p>The selectivity of individual carrier molecules for specific molecules</p> Signup and view all the answers

    What is the primary effect of pH on the absorption of weak acids and weak bases?

    <p>It decreases the ionization of the molecule, making it more absorbable</p> Signup and view all the answers

    Which of the following types of transport is most likely to be saturated?

    <p>Carrier-mediated transport</p> Signup and view all the answers

    What is the primary clinical significance of the broad tissue distribution of biological transport molecules?

    <p>It influences the absorption, distribution, and excretion of drugs</p> Signup and view all the answers

    Which of the following is a characteristic of active transport?

    <p>It is energy-dependent and can move molecules against concentration gradient</p> Signup and view all the answers

    What is the primary role of transporters in the absorption, distribution, and excretion of drugs?

    <p>To facilitate the transport of drugs across membranes</p> Signup and view all the answers

    What is the approximate percentage of the intravascular space in the distribution of a drug?

    <p>5%</p> Signup and view all the answers

    Why is distribution therapeutically important in the case of drugs?

    <p>Drugs can accumulate differentially in different compartments</p> Signup and view all the answers

    What is the primary effect of protein binding on the distribution of a drug?

    <p>It makes a significant fraction of the drug bound to proteins, not freely soluble</p> Signup and view all the answers

    What is the primary reason for the duration of action of THC?

    <p>Distribution of THC in various compartments</p> Signup and view all the answers

    What is the primary function of the Blood-Brain Barrier?

    <p>To restrict the entry of blood-borne xenobiotics into the brain</p> Signup and view all the answers

    What is the primary characteristic of the intracellular space in the distribution of a drug?

    <p>It is a large compartment that accounts for a significant percentage of the total distribution</p> Signup and view all the answers

    What is the primary effect of the distribution of a drug on its therapeutic effect?

    <p>It affects the site of action of the drug</p> Signup and view all the answers

    What is the primary reason why drugs are typically administered at sites distant from their site of action?

    <p>To facilitate the distribution of the drug to its site of action</p> Signup and view all the answers

    Which route of drug administration avoids the first-pass effect?

    <p>Sub-lingual</p> Signup and view all the answers

    What is the primary function of Cytochrome P450 enzymes?

    <p>To oxidize endogenous and xenobiotic organic molecules</p> Signup and view all the answers

    Which of the following statements about Phase I metabolism is TRUE?

    <p>It involves the conversion of a drug to its inactive form</p> Signup and view all the answers

    What is the clinical significance of inter-individual variation in activity levels of Cytochrome P450 enzymes?

    <p>It can lead to variable drug outcomes</p> Signup and view all the answers

    What is the primary concern when co-administering two drugs that are each metabolized by the same CYP enzyme?

    <p>Unanticipated adverse effects</p> Signup and view all the answers

    Which of the following routes of drug administration is associated with the highest bioavailability?

    <p>Intravenous</p> Signup and view all the answers

    What is the term for the process by which a drug is converted to its active form?

    <p>Prodrug activation</p> Signup and view all the answers

    Which of the following statements about CYP2D6 is TRUE?

    <p>It is a member of the CYP2 family</p> Signup and view all the answers

    Study Notes

    Pharmacodynamics and Pharmacokinetics

    • Pharmacodynamics: study of biochemical and physiological effects of xenobiotics on living systems
    • Pharmacokinetics: study of biological, physical, and chemical processes that affect xenobiotic concentration in the blood over time

    Absorption

    • Process of xenobiotic gaining entry into the body (not relevant for parenteral administration)
    • Factors influencing absorption:
      • Lipid partition coefficient (LPC): conc. drug (Octanol phase) / conc. drug (Aqueous phase)
      • pH of the environment
    • Passive diffusion vs. carrier-mediated transport:
      • Passive diffusion: can't be saturated, can't be competed; favors small, uncharged molecules with high LPC
      • Carrier-mediated transport: can be saturated, can be competed; exhibits selectivity for certain molecules

    Distribution

    • Compartments:
      • Intravascular space (~5%)
      • Intracellular space (~40%)
      • Interstitial space (~15%)
      • Other: adipose, bones/teeth, keratinized tissue
    • Importance of distribution:
      • Drugs administered at sites distant from site of action
      • Differential accumulation in different compartments
    • Protein binding:
      • Clinical significance: significant fraction of drug is bound to proteins, not freely soluble
      • Example: THC distribution in various compartments affects duration of action

    Routes of Administration

    • Enteral:
      • Oral (bioavailability, first-pass effect, variable absorption)
      • Sublingual (avoids first-pass effect, limited by LPC)
      • Rectal (avoids first-pass effect, other benefits/costs)
    • Parenteral:
      • Intravenous (intravascular)
      • Intramuscular
      • Subcutaneous
      • Other
    • Inhalation
    • Transdermal

    Drug Metabolism

    • Biotransformation: decrease biological half-life, prodrug activation, procarcinogen activation
    • Phase I metabolism:
      • Cytochrome P450 (CYP) family (57 genes in humans)
      • Multigene family with 12 families and subfamilies
      • Most drugs metabolized by families 1-3
      • NADPH-dependent monooxygenase enzymes
    • Phase II metabolism:
      • Conjugation reactions
    • Clinical significance:
      • Extensive modification of xenobiotics can have unanticipated effects on clinical outcomes
      • Genetic polymorphisms can affect metabolism
      • Co-administration of drugs metabolized by the same CYP can have adverse effects

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