Lecture 4
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Questions and Answers

Which of the following best defines drug absorption?

  • The breakdown of the drug in the gastrointestinal tract
  • The movement of the drug out of the bloodstream after administration
  • The metabolism of the drug within the bloodstream
  • The movement of the drug into the bloodstream after administration (correct)

    • What controls drug absorption?

  • Pores and large plasma proteins
  • Barriers like blood-brain barriers and placenta
  • Capillary walls and endothelial cells (correct)
  • Cell membrane and basement membrane

    • Where does the exchange of materials between blood and cells primarily occur?

  • Capillaries (correct)
  • Basement membrane
  • Endothelial cells
  • Cell membrane

    • Which of the following types of capillaries has more pores allowing materials to move in/out?

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

    What is the site of exchange of materials between blood and cells?

    <p>Capillary walls</p> Signup and view all the answers

    How thick are capillary walls?

    <p>One cell thick</p> Signup and view all the answers

    What allows ions, water, nutrients, and unbound drugs to move in/out of capillaries?

    <p>Pores in the capillary walls</p> Signup and view all the answers

    Which pathway of drug excretion is the most important?

    <p>Renal (urine)</p> Signup and view all the answers

    Under what condition will there be a greater intensity of drug effect?

    <p>Lower plasma protein, leading to increased unbound drug</p> Signup and view all the answers

    What does the Volume Distribution Formula Vd= Amount of drug in the body/Plasma drug concentration represent?

    <p>Volume distribution of the drug in the body</p> Signup and view all the answers

    Which drug excretion pathway involves enterohepatic cycling for some drugs?

    <p>GI (feces)</p> Signup and view all the answers

    In what type of urine are acid drugs mostly ionized?

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

    Which category of FDA Teratogenic Risk indicates absolute fetal abnormalities and not to be used at any time during pregnancy?

    <p>Category X</p> Signup and view all the answers

    What is the effect on drug excretion during the first year of life in neonates/infants?

    <p>Reduced capacity for drug excretion</p> Signup and view all the answers

    Which organ is primarily responsible for the excretion of general anesthetic gases?

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

    What happens to measures of renal function with age?

    <p>They are significantly reduced with age</p> Signup and view all the answers

    What occurs to drug excretion after the first year of life in neonates/infants?

    <p>It gradually becomes proportional to those of the adult</p> Signup and view all the answers

    Which factor does NOT influence the rate of drug absorption?

    <p>Gastrointestinal motility</p> Signup and view all the answers

    In aging individuals, what contributes to decreased drug absorption?

    <p>Decreased intestinal surface area</p> Signup and view all the answers

    Which organ is exposed to the largest amount of drug due to high blood flow?

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

    What happens to water-soluble drugs in the body due to their solubility in water and plasma?

    <p>They are easily distributed throughout the body</p> Signup and view all the answers

    How does aging affect drug binding to plasma proteins?

    <p>Reduces plasma protein levels</p> Signup and view all the answers

    What does a lower percentage of body fat in neonates and infants result in regarding drug distribution?

    <p>Longer durations of action</p> Signup and view all the answers

    What effect does a higher percentage of water in pediatrics have on drug concentrations?

    <p>Increases drug concentrations</p> Signup and view all the answers

    What is the impact of high drug binding on drug distribution into tissues and metabolism?

    <p>Decreases distribution into tissues, decreases metabolism</p> Signup and view all the answers

    What is the main function of the blood-brain barrier (BBB) in relation to drug absorption?

    <p>Allows passage of lipid-soluble drugs and smaller molecules into the brain</p> Signup and view all the answers

    What is most influential in the rapid distribution of drugs into body tissues?

    <p>Blood flow to tissues with high blood flow</p> Signup and view all the answers

    In drug excretion, which type of drugs are mostly ionized in alkaline urine?

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

    What is the primary pathway for the excretion of general anesthetic gases?

    <p>Respiratory excretion</p> Signup and view all the answers

    During the first year of life, what happens to drug excretion in neonates/infants?

    <p>It slows down</p> Signup and view all the answers

    What is the impact of high drug binding on drug distribution into tissues and metabolism?

    <p>Decreased distribution and metabolism</p> Signup and view all the answers

    What is the category of FDA Teratogenic Risk that indicates absolute fetal abnormalities and prohibits use at any time during pregnancy?

    <p>Category X</p> Signup and view all the answers

    How does aging affect measures of renal function such as GFR and creatinine clearance?

    <p>Decreases GFR and creatinine clearance</p> Signup and view all the answers

    What occurs to water-soluble drugs in the body due to their solubility in water and plasma?

    <p>They are excreted in the feces</p> Signup and view all the answers

    In what type of urine are acid drugs mostly ionized?

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

    What does the Volume Distribution Formula Vd= Amount of drug in the body/Plasma drug concentration represent?

    <p>The volume of distribution of the drug in body tissues</p> Signup and view all the answers

    Which organ is exposed to the largest amount of drug due to high blood flow?

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

    Which factor does NOT influence the rate of drug distribution?

    <p>Concentration gradient</p> Signup and view all the answers

    What happens to water-soluble drugs in the body due to their solubility in water and plasma?

    <p>They are more easily distributed throughout the body</p> Signup and view all the answers

    What is the effect of a higher percentage of water in pediatrics on drug concentrations?

    <p>Increased drug concentrations</p> Signup and view all the answers

    How does aging affect drug binding to plasma proteins?

    <p>Decreases free drug available for distribution into tissues</p> Signup and view all the answers

    What is most influential in the rapid distribution of drugs into body tissues?

    <p>Tissues with high blood flow</p> Signup and view all the answers

    Where does the exchange of materials between blood and cells primarily occur?

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

    What happens to drug excretion after the first year of life in neonates/infants?

    <p>Increases significantly</p> Signup and view all the answers

    Which drug excretion pathway involves enterohepatic cycling for some drugs?

    <p>Biliary excretion</p> Signup and view all the answers

    What does a lower percentage of body fat in neonates and infants result in regarding drug distribution?

    <p>Increased distribution to body tissues</p> Signup and view all the answers

    What category of FDA Teratogenic Risk indicates absolute fetal abnormalities and not to be used at any time during pregnancy?

    <p>Category X</p> Signup and view all the answers

    What is the primary site of exchange of materials between blood and cells?

    <p>Capillary walls</p> Signup and view all the answers

    Which of the following barriers allows a large part of the basement membrane to be exposed, allowing large plasma proteins to pass through?

    <p>Capillary walls</p> Signup and view all the answers

    What regulates drug absorption by controlling the movement of the drug into the bloodstream after administration?

    <p>Capillary walls</p> Signup and view all the answers

    Which part of the body has capillary walls that are one cell thick, with pores allowing materials to move in and out?

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

    What is the role of capillaries in relation to drug absorption?

    <p>Movement of drugs into the bloodstream after administration</p> Signup and view all the answers

    Which organ is exposed to the largest amount of drug due to high blood flow?

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

    What controls drug absorption by regulating the movement of drugs into the bloodstream after administration?

    <p>Cell membrane</p> Signup and view all the answers

    Which type of capillaries has more pores allowing materials to move in and out?

    <p>Sinusoidal capillaries</p> Signup and view all the answers

    What allows ions, water, nutrients, and unbound drugs to move in/out of capillaries?

    <p>Pores in capillary walls</p> Signup and view all the answers

    What is mainly responsible for controlling drug absorption by regulating the movement of drugs into the bloodstream after administration?

    <p>Cell membrane</p> Signup and view all the answers

    Study Notes

    • Drug Absorption: Blood-Brain-Barrier (BBB) acts as a selective barrier for large hydrophilic molecules, only allowing passage of smaller, lipid-soluble drugs or through active transport.

    • To enter the brain, drugs must pass through endothelial cells or undergo active transport. Levodopa, a specific drug, is transported into the brain via a transporter.

    • The rate of drug absorption is influenced by factors such as:

      • Surface area of absorption site
      • Blood flow at absorption site
      • Concentration gradient
      • Drug formulations (sizes)
      • Lipid solubility
      • Un-ionized state

    • In neonates and infants:

      • Smaller muscle mass results in slower absorption after IM injections
      • Thinner skin allows for faster absorption of topically applied drugs
      • Less acidic gastrointestinal tract

    • In aging individuals:

      • Decreased intestinal surface area
      • Decreased blood flow to the intestine
      • Decreased gastrointestinal motility
      • Decreased onset of action
      • Decreased absorption of medications

    • Drug Distribution: After a drug gains access to the bloodstream, it is distributed to various tissues and organs of the body.

    • Factors affecting Drug Distribution:

      • Blood flow: Tissues with high blood flow, such as the brain, liver, kidneys, and lungs, are exposed to the largest amount of drug.
      • Blood-Brain Barrier: Brain composition of a large amount of lipid allows for lipid-soluble drugs to pass readily into the brain.
      • Plasma Protein Binding: The distribution of drugs in the body is influenced by the percentage bound to plasma proteins. A higher percentage of binding reduces the free drug available for distribution into tissues.
      • Distribution occurs most rapidly into tissues with high blood flow, such as "rich-vessel organs" (lungs, kidneys, liver, brain).

    • Water-soluble drugs vs. fat-soluble drugs:

      • Water-soluble drugs are more easily distributed throughout the body due to their solubility in water and plasma.
      • Fat-soluble drugs are stored in fatty tissues, acting as a drug reservoir, and are released into the bloodstream over a longer period of time.

    • Drug Binding:

      • Drugs bound to plasma proteins are generally not pharmacologically active and have longer durations of action and low volumes of distribution.
      • Aging reduces plasma protein levels, leading to increased free drug, decreased drug metabolism, and increased drug effect.
      • Neonates and infants have a lower percentage of body fat, resulting in decreased distribution to body tissues and longer drug effects.
      • Pediatrics have a higher percentage of water and are more easily dehydrated, leading to increased drug concentrations.
      • High drug binding reduces the free drug available for distribution into tissues, decreases metabolism, and can be displaced by other drugs.

    • Drug Absorption: Blood-Brain-Barrier (BBB) acts as a selective barrier for large hydrophilic molecules, only allowing passage of smaller, lipid-soluble drugs or through active transport.

    • To enter the brain, drugs must pass through endothelial cells or undergo active transport. Levodopa, a specific drug, is transported into the brain via a transporter.

    • The rate of drug absorption is influenced by factors such as:

      • Surface area of absorption site
      • Blood flow at absorption site
      • Concentration gradient
      • Drug formulations (sizes)
      • Lipid solubility
      • Un-ionized state

    • In neonates and infants:

      • Smaller muscle mass results in slower absorption after IM injections
      • Thinner skin allows for faster absorption of topically applied drugs
      • Less acidic gastrointestinal tract

    • In aging individuals:

      • Decreased intestinal surface area
      • Decreased blood flow to the intestine
      • Decreased gastrointestinal motility
      • Decreased onset of action
      • Decreased absorption of medications

    • Drug Distribution: After a drug gains access to the bloodstream, it is distributed to various tissues and organs of the body.

    • Factors affecting Drug Distribution:

      • Blood flow: Tissues with high blood flow, such as the brain, liver, kidneys, and lungs, are exposed to the largest amount of drug.
      • Blood-Brain Barrier: Brain composition of a large amount of lipid allows for lipid-soluble drugs to pass readily into the brain.
      • Plasma Protein Binding: The distribution of drugs in the body is influenced by the percentage bound to plasma proteins. A higher percentage of binding reduces the free drug available for distribution into tissues.
      • Distribution occurs most rapidly into tissues with high blood flow, such as "rich-vessel organs" (lungs, kidneys, liver, brain).

    • Water-soluble drugs vs. fat-soluble drugs:

      • Water-soluble drugs are more easily distributed throughout the body due to their solubility in water and plasma.
      • Fat-soluble drugs are stored in fatty tissues, acting as a drug reservoir, and are released into the bloodstream over a longer period of time.

    • Drug Binding:

      • Drugs bound to plasma proteins are generally not pharmacologically active and have longer durations of action and low volumes of distribution.
      • Aging reduces plasma protein levels, leading to increased free drug, decreased drug metabolism, and increased drug effect.
      • Neonates and infants have a lower percentage of body fat, resulting in decreased distribution to body tissues and longer drug effects.
      • Pediatrics have a higher percentage of water and are more easily dehydrated, leading to increased drug concentrations.
      • High drug binding reduces the free drug available for distribution into tissues, decreases metabolism, and can be displaced by other drugs.

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    Fundamentals of Pharmacology Lecture 4 PDF

    Description

    Test your knowledge of drug absorption, distribution, and excretion with this quiz based on the fundamentals of pharmacology lecture by Hoang Nguyen, M.D., Ph.D., RPh., FACHE. Assess your understanding of mechanisms and learning objectives related to pharmacokinetics.

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