MPP lecture 3
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What is the primary purpose of Phase II reactions in drug metabolism?

  • To conjugate metabolites with substances for better solubility (correct)
  • To modify drugs to enhance their pharmacological activity
  • To oxidize drugs for faster excretion
  • To increase the lipophilicity of compounds

    • Which Phase II reaction involves the addition of glucuronic acid?

  • Acetylation
  • Sulfation
  • Glucuronidation (correct)
  • Methylation

    • Which of the following is a consequence of increased CYP enzyme activity due to inducers?

  • Decreased drug metabolism rates
  • Enhanced therapeutic effects of drugs
  • Reduced plasma drug concentrations (correct)
  • Increased plasma drug concentrations

    • What does the 'CYP' in the P450 enzyme family stand for?

    <p>Cytochrome P450</p> Signup and view all the answers

    In the P450 enzyme family designation, what does the number following 'CYP' represent?

    <p>The specific isozyme within the subfamily</p> Signup and view all the answers

    Which phase of drug metabolism is primarily involved in modifying compounds to make them more reactive?

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

    What results from the sulfation of compounds during Phase II metabolism?

    <p>Attachment of sulfate groups</p> Signup and view all the answers

    What is a characteristic of the metabolites formed from Phase II reactions?

    <p>More polar and less biologically active</p> Signup and view all the answers

    Which of the following statements about P450 inducers is incorrect?

    <p>They can inhibit the metabolism of other drugs.</p> Signup and view all the answers

    What process primarily occurs during the modification reaction step of Phase I metabolism?

    <p>Reduction of the oxidized drug complex</p> Signup and view all the answers

    What is the primary purpose of drug biotransformation in the body?

    <p>To convert drugs into more polar, excretable products</p> Signup and view all the answers

    Which type of drug is activated through metabolic processes?

    <p>Inactive prodrug</p> Signup and view all the answers

    What is a common outcome of Phase I drug biotransformation?

    <p>Synthesis of polar metabolites for excretion</p> Signup and view all the answers

    Which of the following best describes the role of P450 enzymes in drug metabolism?

    <p>Participate in the metabolism of both endogenous and exogenous substances</p> Signup and view all the answers

    What characterizes a Phase II drug biotransformation reaction?

    <p>Conjugation with another substance to facilitate excretion</p> Signup and view all the answers

    Which of the following accurately describes an inactive prodrug?

    <p>A compound that requires metabolism to activate</p> Signup and view all the answers

    Which of the following is NOT a mechanism involved in Phase I reactions?

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

    What distinguishes metabolites from parent drugs?

    <p>Metabolites are derived through enzymatic reactions</p> Signup and view all the answers

    Where does the majority of drug biotransformation occur in the body?

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

    Which of the following is a result of an active drug being metabolized?

    <p>It may be converted to an inactive or toxic form</p> Signup and view all the answers

    What is the primary reason drug biotransformation is necessary?

    <p>To convert lipophilic drugs to more excretable products.</p> Signup and view all the answers

    Which organ is primarily responsible for drug metabolism?

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

    In the context of drug biotransformation, what can happen to an inactive prodrug?

    <p>It can be converted into an active drug.</p> Signup and view all the answers

    What type of reaction occurs during Phase I of drug biotransformation?

    <p>Oxidation and reduction reactions introduce functional groups.</p> Signup and view all the answers

    What is the role of cytochrome P450 enzymes in drug metabolism?

    <p>They catalyze oxidation and reduction reactions.</p> Signup and view all the answers

    Which of the following is NOT a way drug biotransformation can alter drugs?

    <p>An active drug is converted to a non-excretable metabolite.</p> Signup and view all the answers

    Which process is NOT associated with Phase I biotransformation?

    <p>Conjugation of metabolites.</p> Signup and view all the answers

    What is the general outcome of Phase II biotransformation?

    <p>Preparation of metabolites for conjugation and excretion.</p> Signup and view all the answers

    What is the likely effect of increased drug metabolism on target tissues?

    <p>Less active drug is present in the target tissues.</p> Signup and view all the answers

    Which mechanism of Phase II reaction involves the addition of sulfate groups?

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

    What is a typical outcome of Phase II reactions in terms of compound characteristics?

    <p>Greater water solubility</p> Signup and view all the answers

    Which component is involved in the activation of the P450 enzyme complex during Phase I metabolism?

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

    How are the different isozymes of the P450 family designated?

    <p>By a combination of letters and numbers</p> Signup and view all the answers

    What does CYP stand for in reference to P450 enzymes?

    <p>Cytochrome P450</p> Signup and view all the answers

    What effect do P450 inducers have on CYP enzymes?

    <p>They stimulate gene transcription</p> Signup and view all the answers

    Which of the following outcomes is most likely from Phase I reactions?

    <p>Conversion of lipophilic drugs to more polar compounds</p> Signup and view all the answers

    What is a key role of Phase I reactions in drug metabolism?

    <p>Making drugs more reactive or polar</p> Signup and view all the answers

    What does the second number in the P450 enzyme name indicate?

    <p>The isozyme within the family</p> Signup and view all the answers

    Which Phase II reaction involves the addition of methyl groups?

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

    Study Notes

    Drug Biotransformation Overview

    • Xenobiotics are foreign substances not naturally found in the body.
    • Drug biotransformation alters drugs for excretion due to their physicochemical properties.
    • Most drugs are lipophilic and tightly bound to plasma proteins.
    • Transformation produces more polar compounds for easier excretion.
    • The liver serves as the primary organ for drug metabolism.

    Types of Drug Biotransformation

    • Active drugs can convert into inactive substances.
    • Active drugs may lead to active or toxic metabolites.
    • Inactive prodrugs can be transformed into active drugs.
    • Unexcretable drugs can be metabolized into excretable forms.

    Phase I Reactions

    • Phase I focuses on oxidation and reduction, converting lipophilic drugs into more polar molecules.
    • Mechanisms include:
      • Oxidation: Addition of oxygen or removal of hydrogen (e.g., ethanol to acetaldehyde).
      • Reduction: Removal of oxygen or addition of hydrogen (e.g., nitro compounds to amino groups).
      • Hydrolysis: Break down of compounds with water (e.g., esters to alcohols and acids).
    • Enzymes involved are cytochrome P450 (CYP) and P450 Reductase.
    • Outcomes include further processing in Phase II or excretion.

    Phase II Reactions

    • Phase II aims to increase solubility of metabolites for excretion through conjugation with other substances.
    • Mechanisms consist of:
      • Glucuronidation: Addition of glucuronic acid (e.g., bilirubin conjugation).
      • Sulfation: Addition of sulfate groups (e.g., steroid sulfation).
      • Acetylation: Addition of acetyl groups (e.g., aromatic amine acetylation).
      • Methylation: Addition of methyl groups (e.g., catecholamine methylation).
    • These reactions typically result in compounds that are more polar and less biologically active for easier excretion.

    Summary of Stages

    • Phase I reactions modify compounds to be more reactive or polar but may not enhance excretion directly.
    • Phase II reactions leverage conjugation to improve solubility and excretion.

    P450 Enzyme Family Characteristics

    • Family represented by a number after "CYP", with a capital letter indicating the subfamily and a second number for a specific isozyme (e.g., CYP3A4).
    • P450 inducers enhance gene transcription for CYP enzymes, leading to increased drug metabolism.

    Effects of P450 Inducers

    • Increasing drug metabolism can lead to:
      • Lower plasma drug concentrations.
      • Reduced drug activity if metabolite is inactive.
      • Increased drug activity if metabolite is active.
      • Diminished therapeutic drug effects.

    P450 Inhibitors

    • Inhibition may arise from competition for the same isozyme.
    • Can result in adverse effects and altered drug efficacy.

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    MPP Lecture 3 Principles of Pharmacology PDF

    Description

    Explore the fascinating world of pharmacology through this quiz, focusing on drug biotransformation, metabolites, and the role of P450 enzymes. Understand how xenobiotics interact within the body and the significance of prodrugs in drug therapy. Test your knowledge on these critical concepts in drug metabolism.

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