Drug Metabolism I - MOOC Quiz
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Questions and Answers

What is the primary organ involved in the metabolism of drugs?

  • Liver (correct)
  • Lung
  • Kidney
  • Intestinal mucosa

    • First-pass metabolism refers to the initial metabolism of drugs in the liver before reaching the general circulation.

    False

    What is the main consequence of drug metabolism?

    Termination of drug action

    Drugs are converted from lipophilic compounds to _______ products for easier excretion.

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

    Match the following terms with their descriptions:

    <p>Absorption = Process of a drug entering the bloodstream Distribution = Dispersion of the drug throughout body tissues Metabolism = Biochemical modification of drugs Elimination = Removal of drugs from the body</p> Signup and view all the answers

    Which of the following may influence drug metabolism?

    <p>All of the above</p> Signup and view all the answers

    Metabolism of one drug does not affect the metabolism of another drug.

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

    Name one site where first-pass metabolism can occur.

    <p>Intestinal mucosa or lung</p> Signup and view all the answers

    Which phase of drug metabolism involves functionalization reactions?

    <p>Phase I</p> Signup and view all the answers

    Drug metabolism is always considered detoxification.

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

    What is a prodrug?

    <p>A prodrug is an inactive drug that requires metabolic conversion to become an active form.</p> Signup and view all the answers

    The process of linking an endogenous moiety to a drug or metabolite in drug metabolism is called __________.

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

    Which of the following compounds are least subject to metabolic transformations?

    <p>Both A and B</p> Signup and view all the answers

    What is lethal synthesis?

    <p>Lethal synthesis refers to the metabolic conversion of a nontoxic compound into a toxic form.</p> Signup and view all the answers

    The liver is the organ with the highest levels of drug metabolizing enzymes.

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

    Study Notes

    Drug Metabolism I - Lecture Topics

    • Phase 1: Basic Principles of Drug Metabolism (DM)
    • MOOC (Massive Open Online Course)

    Course Objectives

    • Comprehend, apply, and evaluate the key concepts and principles of drug metabolism.
    • Identify and characterize major metabolites of a given drug and the specific enzymes involved in its metabolism.

    The Fate of a Drug

    • Drugs begin with a dose.
    • Absorption to the body occurs.
    • Distribution is to most tissues and then to plasma where some is protein-bound and some is free.
    • Metabolism occurs, and the drug is eliminated through renal excretion.
    • Distribution also occurs to the biophase where receptor binding results in an effect.
    • These processes are grouped in Pharmacokinetics and Pharmacodynamics.

    Stages of Drug Metabolism

    • Absorption: Drug travels to the site of administration, moves into the bloodstream.
    • Distribution: Drug moves throughout the body. The drug/metabolites move into the tissues.
    • Metabolism: Drug/metabolites change in tissues.
    • Elimination: Drug/metabolites are removed from the body in urine, feces, or bile.

    Drug Metabolism

    • Metabolic breakdown of drugs by living organisms (xenobiotics), mostly in the liver.
    • Converts lipophilic compounds to hydrophilic compounds for easier excretion.
    • Can turn procarcinogens into toxic mutagens.
    • Individual variations in factors (genetics, physiology) significantly impact metabolic rates, and the metabolism of one xenobiotic may influence the metabolism of others.

    Metabolism in Non-Hepatic Tissues

    • Intestinal mucosa (GI tract)
    • Kidney
    • Lung
    • Bacteria in the GI tract are involved in drug metabolism.

    First-Pass Metabolism

    • A major process of metabolism that happens in the liver and intestinal tract before reaching the general circulation.
    • Metabolism happens in the gut which results in inactive metabolites.

    Drug Metabolism Pathways

    • Phase 1: Introduces or uncovers polar groups (such as CO₂, OH, or NH₂) via oxidation, reduction, or hydrolysis.

    • Phase 2: Links an endogenous moiety (like GSH, sulfate, glycine, glucuronic acid) to the original drug or phase 1 metabolite. This creates polar metabolites which cannot cross membranes and are excreted.

    • Phase 3: Conjugated xenobiotics are processed further, recognized by efflux transporters, and removed from the cells.

    Drug Metabolism Example-Morphine

    • A hydrophobic drug that is metabolized via Phase 1 (demethylation) & Phase 2 (glucuronidation) to become more hydrophilic and excreted.

    Implications of Drug Metabolism

    • Termination of drug action
    • Activation of prodrugs
    • Bioactivation and toxification
    • Carcinogenesis

    Two Xenobiotic Categories

    • Hydrophilic compounds (like saccharin, strong acids, or bases) are largely unaffected by metabolic transformations.

    • Highly lipophilic compounds (like DDT): Many metabolic reactions often do not lead to inactivation or detoxification, instead, some metabolites can be as potent as the original, bind covalently to proteins, DNA, and cause mutagenesis/carcinogenesis.

    Lethal Synthesis

    • The metabolic conversion of non-toxic Parathion to paraoxon, a potent acetylcholinesterase inhibitor.

    Major Sites of Metabolism

    • Drug metabolism occurs in various tissues, but the liver is the primary organ for metabolism, followed by the lungs, kidneys, and intestine, respectively. The CNS has very low metabolic activity.

    • The liver, due to high blood flow and numerous metabolic enzymes, is the primary site of drug clearance:

      - High: liver
- Medium: lungs, kidneys, intestine
- Low: skin, testes, placenta, adrenals
- Very low: CNS

    • Extrahepatic microsomal enzymes and non-microsomal enzymes (like hepatic enzymes) also contribute to the metabolism.

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    Related Documents

    PHC511 Drug Metabolism I Lecture Topics PDF

    Description

    Test your knowledge on the basic principles of drug metabolism in our Drug Metabolism I MOOC. This quiz covers key concepts such as absorption, distribution, metabolism, and elimination of drugs. Evaluate your understanding of the enzymes involved and the fate of drugs in the body.

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