Pharma - Berto - L5 part 2
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Questions and Answers

What is the cofactor used by acetyltransferase in the acetylation process?

  • Acetyl CoA (correct)
  • Glutathione
  • 3’-phosphoadenosine-5’-phosphosulfate
  • NADH
  • Which enzyme is responsible for transferring methyl groups to catecholamines?

  • Sulfotransferase
  • Acetyltransferase
  • DNMT
  • COMT (correct)
  • What genetic variation is characteristic of 'poor' metabolizers?

  • Duplication of gene alleles
  • Increased enzyme activity
  • Homozygosity for mutations (correct)
  • Reduced levels of substrate
  • Which phase II metabolic process can result in more lipophilic forms of a drug?

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

    What might result from individuals who are rapid acetylators when treated with isoniazid?

    <p>Scarce response and reduced side effects</p> Signup and view all the answers

    Which polymorphism is characterized by variants that slow down the activity of CYP2D6?

    <p>*4 and *5 variants</p> Signup and view all the answers

    What type of reaction is methylation considered in post-translational modifications?

    <p>Regulatory mechanism</p> Signup and view all the answers

    Which CYP enzyme's polymorphism is specifically linked to low metabolic activity in Chinese populations?

    <p>CYP2C19</p> Signup and view all the answers

    Which of the following factors can modulate the metabolism of caffeine?

    <p>Genetic factors</p> Signup and view all the answers

    What type of reactions are Phase II reactions primarily characterized as?

    <p>Biosynthetic reactions</p> Signup and view all the answers

    Which of the following functions as a cofactor in the glucuronidation reaction?

    <p>Uridine diphosphate glucuronic acid</p> Signup and view all the answers

    Which enzyme is primarily associated with glucuronidation?

    <p>UDP-glucuronyl transferase</p> Signup and view all the answers

    What is the main role of glutathione-S-transferase (GST) in Phase II reactions?

    <p>To facilitate conjugation with glutathione</p> Signup and view all the answers

    Which of the following Phase II reactions does NOT involve ATP consumption?

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

    What role does glutathione conjugation serve in the detoxification process?

    <p>Increases solubility for excretion</p> Signup and view all the answers

    Which of these functional groups is NOT typically involved in Phase II reactions?

    <p>-PO4</p> Signup and view all the answers

    Which organ is NOT mentioned as having UDP-glucuronyl transferase activity for glucuronidation?

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

    What is a common substrate for glucuronidation?

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

    In the context of Phase II reactions, which statement about energy consumption is true?

    <p>ATP is consumed to activate the cofactor in some reactions.</p> Signup and view all the answers

    What characterizes pharmacodynamic interactions?

    <p>They occur at the site of the receptor.</p> Signup and view all the answers

    Which scenario describes pharmacokinetic interactions?

    <p>One drug changes the concentration of another at the site of action.</p> Signup and view all the answers

    What is a potential positive outcome of drug interactions?

    <p>Development of beneficial effects.</p> Signup and view all the answers

    What is a common misconception about drug interactions?

    <p>They are always harmful.</p> Signup and view all the answers

    What defines a scenario of drug inactivation outside the organism?

    <p>Two drugs are mixed leading to their reduced effectiveness.</p> Signup and view all the answers

    Which statement regarding drug interactions is true?

    <p>Pharmacodynamic interactions do not change drug concentrations.</p> Signup and view all the answers

    In what way can drug A affect drug B pharmacodynamically?

    <p>By modifying the receptor's response to drug B.</p> Signup and view all the answers

    What is a primary goal when studying drug interactions in a clinical setting?

    <p>To identify interactions that lead to significant side effects.</p> Signup and view all the answers

    What does it mean if drug interactions are beneficial?

    <p>They improve patient outcomes or enhance therapeutic effects.</p> Signup and view all the answers

    Which of the following is NOT true regarding drug interactions?

    <p>They only occur inside the body.</p> Signup and view all the answers

    What is the primary risk associated with individuals who have a mutation in the succinylcholine esterase enzyme?

    <p>Prolonged neuromuscular block leading to respiratory paralysis</p> Signup and view all the answers

    Which factor primarily affects metabolic activity in newborns related to drug metabolism?

    <p>Reduced hepatic and metabolic capacity</p> Signup and view all the answers

    What is the consequence of enzymatic induction in drug metabolism?

    <p>Decreased effectiveness of substrate drugs due to increased enzyme synthesis</p> Signup and view all the answers

    What type of drug interaction occurs when one drug inhibits the metabolism of another drug?

    <p>Enzymatic inhibition</p> Signup and view all the answers

    Which enzyme family is mainly involved in drug metabolic interactions?

    <p>Cytochrome p450</p> Signup and view all the answers

    What nutritional factor is known to decrease enzymatic activity affecting drug metabolism?

    <p>Deficiency of certain vitamins</p> Signup and view all the answers

    How does chronic alcohol abuse influence cytochrome activity related to drug metabolism?

    <p>It induces specific cytochrome isoforms</p> Signup and view all the answers

    What is the primary effect of the gray baby syndrome in relation to drug metabolism in newborns?

    <p>Reduced conjugation with glucuronic acid</p> Signup and view all the answers

    Which drug interaction mechanism can lead to an increased level of terfenadine when co-administered with erythromycin?

    <p>Enzymatic inhibition</p> Signup and view all the answers

    Which of the following is NOT a characteristic of enzymatic induction in drug metabolism?

    <p>Immediate therapeutic effects</p> Signup and view all the answers

    Study Notes

    Phase II Reactions Overview

    • Phase II reactions are biosynthetic processes conjugating Phase I metabolites with endogenous compounds.
    • Key functional groups involved: –OH, COOH, -NH2, -SH.
    • These reactions require ATP for cofactor activation, utilizing enzymes typically found in the cytoplasm.

    Key Phase II Reactions

    • Glucuronidation: Predominant Phase II reaction involving UDP-glucuronyl transferase; substrate range includes alcohols, phenols, amines, and others.
    • Sulfation: Utilizes 3’-phosphoadenosine-5’-phosphosulfate (PAPs) with sulfotransferase enzyme; substrates include phenols, alcohols, and amines.
    • Methylation: A post-translational modification catalyzed by methyltransferases, affects both proteins and DNA; crucial for gene expression regulation.
    • Acetylation: Uses acetyl CoA and led by acetyltransferase; can create more lipophilic drug forms and is significant in neurotransmitter synthesis.
    • Conjugation with Amino Acids and Glutathione: Important for detoxifying various substances, including toxins like aflatoxin.

    Role of Glutathione

    • Glutathione-S-transferase (GST) plays a vital role in detoxification; facilitates the conjugation of modified xenobiotics to glutathione, promoting active transport out of the cells.

    Genetic Factors in Drug Metabolism

    • Genetic polymorphisms influence metabolic capacity, classified into "poor" or "rich" metabolizers based on enzyme activity.
    • Acetylation Phenotypes: Slow and rapid acetylators impact drug metabolism and side-effect profiles (e.g., isoniazid).
    • Cytochrome P450 Polymorphisms: Variants CYP2C19, CYP2D6, and CYP2C9 significantly affect drug metabolism, leading to varied therapeutic effects and toxicity.

    Physiological and Pathological Influences

    • Age: Newborns exhibit reduced hepatic function, while the elderly show decreased oxidative metabolism.
    • Hepatic Diseases: Serious liver conditions can profoundly impact drug metabolism.

    Metabolic Drug Interactions

    • Two primary types:
      • Enzymatic Induction: Increase in enzyme synthesis leading to reduced drug effectiveness (e.g., due to chronic administration of certain drugs).
      • Enzymatic Inhibition: Involves immediate enzyme activity blockade, can elevate drug levels and enhance toxicity risk.

    Nutritional Factors

    • Nutrition influences biotransformation; deficiencies in vitamins or minerals can hinder enzyme activity.
    • Certain food compounds, like those from grapefruit juice, can inhibit cytochrome enzymes, affecting drug metabolism.

    Drug Interactions Explained

    • Interactions can occur pharmacodynamically (altering drug action without concentration changes) or pharmacokinetically (changing drug concentration at the action site).
    • Outside the organism interactions can also lead to inactivation or reduced efficacy of mixed drugs before administration.

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