Introduction to Pharmacokinetics
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Questions and Answers

What does pharmacodynamics study?

  • The rate of drug excretion from the body
  • The mechanism of action of drugs (correct)
  • The distribution of drugs within the bloodstream
  • The absorption of drugs in the body

    • Which of the following components is NOT part of pharmacokinetics?

  • Distribution
  • Receptors (correct)
  • Metabolism
  • Excretion

    • Why is understanding pharmacokinetics important for drug administration?

  • It ensures the effective timing and frequency of dosages. (correct)
  • It evaluates patient’s psychological responses to drugs.
  • It reduces the chances of allergic reactions.
  • It helps in determining drug cost-effectiveness.

    • What does the acronym ADME stand for in pharmacokinetics?

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

    How is digoxin, used for treating heart failure, best administered for maximum effect?

    <p>Once daily</p> Signup and view all the answers

    What is the primary mechanism by which most drugs are absorbed across epithelial cells?

    <p>Simple diffusion</p> Signup and view all the answers

    Which type of drugs is absorbed more effectively in the stomach?

    <p>Acidic drugs</p> Signup and view all the answers

    What is a significant characteristic of carrier-mediated transport for drug absorption?

    <p>It requires energy</p> Signup and view all the answers

    Basic drugs are excreted faster in which type of urine?

    <p>Acidic urine</p> Signup and view all the answers

    What role do tight junctions in epithelial cells play in drug absorption?

    <p>They limit the passage of hydrophilic drugs</p> Signup and view all the answers

    Which of the following drugs would likely not be absorbed effectively when reaching the kidneys due to its ionization?

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

    What factor contributes to a drug's absorption in the small intestine rather than the stomach?

    <p>Increased surface area in the small intestine</p> Signup and view all the answers

    Which drug property is NOT mentioned as a factor affecting drug absorption?

    <p>Molecular weight</p> Signup and view all the answers

    Which patient condition may negatively impact the absorptive surface and therefore drug absorption?

    <p>Celiac disease</p> Signup and view all the answers

    What is a characteristic of highly polar drugs regarding their absorption route?

    <p>They cannot be effectively administered orally.</p> Signup and view all the answers

    How does a 50% decrease in the volume of distribution affect the half-life of a drug?

    <p>The half-life will decrease.</p> Signup and view all the answers

    What is a key difference between IV injection and oral administration of the same drug dose?

    <p>IV injection skips the absorption phase.</p> Signup and view all the answers

    How long does it typically take for a drug administered orally to reach steady state plasma concentration compared to continuous infusion?

    <p>Longer for oral than for continuous infusion.</p> Signup and view all the answers

    In a two-compartment model, what does the alpha-phase typically represent?

    <p>Distribution of drug into the tissues.</p> Signup and view all the answers

    What happens to steady state plasma concentration when a drug eliminated via zero-order kinetics is doubled?

    <p>It doubles.</p> Signup and view all the answers

    Which pharmacokinetic factor is affected by the drug's route of administration?

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

    Which factors determine the appropriate route of drug administration?

    <p>Patient-related and drug-related factors.</p> Signup and view all the answers

    What is a primary focus of studying pharmacokinetics?

    <p>Monitoring drug absorption and elimination.</p> Signup and view all the answers

    Which drug is commonly administered sublingually for rapid action in emergency cases?

    <p>Glyceryl trinitrate</p> Signup and view all the answers

    Which route of drug administration involves injecting a drug into the subcutaneous fat?

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

    What is the most common muscle used for intramuscular injections?

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

    Which of these statements about oral drug administration is true?

    <p>Most drugs taken orally can have delayed effects.</p> Signup and view all the answers

    What angle should be maintained when administering an intramuscular injection?

    <p>90 degrees</p> Signup and view all the answers

    Which medication is often injected intramuscularly for immediate effect?

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

    During a subcutaneous injection, what potential complication should be monitored for?

    <p>Abscess formation</p> Signup and view all the answers

    Which route allows for the fastest onset of action among the following options?

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

    What is the primary reason for administering Tab.Propranolol with food?

    <p>To reduce the risk of gastrointestinal irritation</p> Signup and view all the answers

    Why is there a difference in the dose of Propranolol when administered orally versus intravenously?

    <p>Intravenous administration delivers the drug directly into circulation, requiring a lower dose</p> Signup and view all the answers

    Which of the following factors significantly influences the bioavailability of a drug?

    <p>Chemical structure of the drug</p> Signup and view all the answers

    What is one primary mechanism of how lipophilic drug molecules cross cell membranes?

    <p>Passive diffusion through the lipid bilayer</p> Signup and view all the answers

    What distinguishes phase I reactions from phase II reactions in drug metabolism?

    <p>Phase I introduces functional groups, while phase II involves conjugation with larger molecules</p> Signup and view all the answers

    Which parameter is expressed in units of clearance related to drug elimination?

    <p>Volume per time, usually in mL/min</p> Signup and view all the answers

    Which route of administration generally has the highest bioavailability?

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

    How does pH influence drug permeability across cell membranes?

    <p>It alters the ionization state of the drug</p> Signup and view all the answers

    Study Notes

    Introduction to Pharmacokinatics

    • Pharmacokinectics is the study of drug movement in the body
    • It involves the processes of absorption, distribution, metabolism, and excretion (ADME)
    • Pharmacodynamics is the study of the drug's mechanism of action on the body

    Principles of Pharmacokinectics

    • Drugs are administered differently due to pharmacokinetics
    • Digoxin (heart failure) is better administered once daily
    • Paracetamol (fever) is typically given 3-4 times a day
    • Insulin (diabetes) is less effective when administered orally

    Learning Objectives

    • Define pharmacokinectics
    • Describe the principal mechanisms of drug movement in the body
    • Explain how drug molecules cross cell membranes
    • Identify the main routes of drug administration
    • Determine drug bioavailability
    • Explain drug metabolism and excretion
    • Discuss drug clearance and half-life
    • Describe how drug administration affects concentration versus time

    Routes of Drug Administration

    • Oral route: Drugs taken by mouth, absorbed in the small intestine
    • Inhalation route: Drugs inhaled into the lungs
    • Topical route: Drugs applied to the skin or mucous membranes
    • Rectal route: Drugs inserted into the rectum
    • Parenteral route: Drugs injected (intravenous, intramuscular, subcutaneous, intradermal)

    Drug Absorption

    • Movement of drug from administration to systemic circulation
    • Depends on chemical nature of drug
    • Ionization and pH influence drug absorption
    • Lipid solubility determines drug crossing cell membranes

    Drug Distribution

    • Reversible transfer of drug between the blood and extra-vascular fluids (tissues)
    • Factors affecting distribution: degree of ionization, lipid solubility
    • Drugs can be concentrated in specific tissues

    Plasma Protein Binding

    • Acidic drugs bind to albumin, basic drugs to glycoprotein
    • Prolongs drug availability (reservoir effect)
    • Drug displacement interactions can occur

    Bioavailability

    • Fraction of drug absorbed and entering systemic circulation unchanged
    • Affected by administration route and other factors

    First-Pass Metabolism

    • Metabolism of drug in the liver before reaching systemic circulation is affected by the route of administration
    • Some drugs experience significant first-pass metabolism

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    Description

    This quiz focuses on pharmacokinetics, the study of drug movement within the body, covering essential processes such as absorption, distribution, metabolism, and excretion (ADME). You'll learn about drug administration routes, bioavailability, and how various factors affect drug concentration over time. Test your understanding of key principles and mechanisms governing how drugs operate in the body.

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