Drug Absorption and Routes of Administration Quiz
10 Questions
5 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Why is drug absorption through the gastrointestinal tract among the best understood processes?

  • Absorption of drugs through the gastrointestinal tract is always complete.
  • Gastric acid and digestive enzymes inactivate drugs in the gut lumen. (correct)
  • Biological phospholipid membranes are impermeable to lipid-soluble drugs.
  • First-pass metabolism does not occur in the gut wall or liver.
  • What explains why the bioavailability of an orally administered drug is typically less than 100%?

  • First-pass metabolism occurs only in the kidneys.
  • The drug is impermeable to biological phospholipid membranes.
  • Absorption through the gastrointestinal tract is always complete.
  • Inactivation within the gut lumen and pre-systemic metabolism affect drug availability. (correct)
  • Which process explains why most drugs are absorbed incompletely unless administered intravenously?

  • Absence of any inactivation mechanisms within the gut lumen
  • Complete absorption through lipid-soluble membranes
  • Pre-systemic ('first-pass') metabolism in the gut wall and liver (correct)
  • Systemic effect exerted by most drugs
  • How can the bioavailability of a drug formulation be measured experimentally?

    <p>By measuring concentration vs. time curves following oral and intravenous administration</p> Signup and view all the answers

    What defines bioavailability in terms of drug administration?

    <p>The total amount of a drug that reaches systemic circulation unchanged</p> Signup and view all the answers

    What is a key factor that influences the drug formulation's disintegration, dispersion, and dissolution in the gastrointestinal tract?

    <p>Inactivation in the gut wall</p> Signup and view all the answers

    In what year did an epidemic of phenytoin intoxication occur in Australia due to changes in the drug's excipient?

    <p>1968-69</p> Signup and view all the answers

    What happened when the manufacturing process of digoxin in the UK was changed?

    <p>Decreased bioavailability</p> Signup and view all the answers

    What factor led to confusion when restoring the original manufacturing conditions of digoxin in the UK?

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

    Why did differences in bioavailability lead to an epidemic of phenytoin intoxication in Australia?

    <p>Alteration of the excipient from calcium sulfate to lactose</p> Signup and view all the answers

    Study Notes

    Drug Absorption and Bioavailability

    • Drug absorption through the gastrointestinal tract is well understood due to extensive research on factors influencing this process, including pH, solubility, and gastrointestinal motility.
    • Bioavailability of orally administered drugs is typically less than 100% due to factors like first-pass metabolism, incomplete absorption, and degradation in the gastrointestinal tract.
    • Incomplete absorption of most drugs, unless given intravenously, is primarily explained by the first-pass effect, where a portion of the drug is metabolized before reaching systemic circulation.

    Measuring Bioavailability

    • Experimental measurement of bioavailability can be performed through pharmacokinetic studies, comparing the concentration of drug in systemic circulation after different routes of administration.
    • Bioavailability is defined as the proportion of a drug that enters systemic circulation when it is administered and is available for activity, usually expressed as a percentage.

    Factors Influencing Drug Formulation

    • A key factor influencing drug formulation's disintegration, dispersion, and dissolution in the gastrointestinal tract is the drug's physicochemical properties, including particle size and solubility.

    Case Studies

    • An epidemic of phenytoin intoxication occurred in Australia in 1996 due to changes in the excipients used in the drug formulation, leading to variations in absorption rates.
    • Changes in the manufacturing process of digoxin in the UK resulted in an increase in toxicity among patients due to altered drug bioavailability.
    • Confusion arose when restoring original manufacturing conditions of digoxin due to the variability in patient responses and differences in bioavailability linked to the new production methods.
    • Differences in bioavailability in phenytoin led to an epidemic of intoxication because the adjustments in excipients caused significant fluctuations in drug absorption, resulting in dangerous therapeutic levels.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Description

    Test your knowledge about drug absorption, bioavailability, bioequivalence, generic vs. proprietary prescribing, and different routes of drug administration. Understand how the rate and extent of penetration of biological phospholipid membranes affect drug absorption.

    More Like This

    Bioavailability and Drug Absorption
    20 questions
    Bioavailability and Drug Absorption Quiz
    10 questions
    Pharmacology Chapter on Drug Absorption
    37 questions
    Use Quizgecko on...
    Browser
    Browser