Drug Dissolution and Factors Affecting Absorption Quiz
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Questions and Answers

What does Fick's First Law of Diffusion state?

  • The rate of diffusion is proportionate to cross-sectional area and diffusion coefficient only
  • The rate of diffusion is proportionate to concentration gradient, cross-sectional area, and diffusion coefficient (correct)
  • The rate of diffusion is proportionate to concentration gradient and diffusion coefficient only
  • The rate of diffusion is proportionate to concentration gradient and cross-sectional area only

    • What does the diffusion coefficient (D) represent?

  • The concentration of solute in g/mL of solution
  • The decrease in chemical potential/free energy
  • The rate of diffusion in a specific solvent at a specific temperature
  • The amount of solute diffusing across 1 cm$^2$ in 1 second (correct)

    • What does the flux (J) measure in diffusion?

  • The amount of substance that will flow through a unit area during a unit time interval (correct)
  • The rate of diffusion of a specific solute
  • The decrease in chemical potential/free energy
  • The concentration gradient of the solute

    • When does diffusion stop according to the text?

    <p>When the concentration gradient (dc/dx)* = 0</p> Signup and view all the answers

    What is the main buffer system in the small intestine?

    <p>Bicarbonate system</p> Signup and view all the answers

    What is the approximate fasting pH range in the duodenum of the small intestine?

    <p>6.2-7.0</p> Signup and view all the answers

    What is the approximate fasting pH in the jejunum of the small intestine?

    <p>6.8</p> Signup and view all the answers

    What is the fasting concentration of bile salts in the small intestine?

    <p>3 mM</p> Signup and view all the answers

    What is the approximate concentration of bile salts in the small intestine in the fed state?

    <p>5-7 mM</p> Signup and view all the answers

    What is the approximate bile salt/phospholipids ratio in the small intestine?

    <p>4:1</p> Signup and view all the answers

    What is the approximate surface area of the intestine needed for sufficient oral absorption?

    <p>800 cm2</p> Signup and view all the answers

    What does the Biopharmaceutical Classification System (BCS) classify based on for oral drug absorption?

    <p>Permeability and solubility of the drug</p> Signup and view all the answers

    What is the effective permeability (Peff) of the intestine for drug absorption?

    <p>$10^{-4}$ cm/s</p> Signup and view all the answers

    Which BCS class of drugs may qualify for a waiver of in vivo bioavailability and bioequivalence studies?

    <p>Class I</p> Signup and view all the answers

    What is the approximate transit time of drug absorption in the stomach in the fasting state?

    <p>12 minutes</p> Signup and view all the answers

    What is the approximate transit time of drug absorption in the intestines in the fasting state?

    <p>3-4 hours</p> Signup and view all the answers

    What is the driving force for the transfer of one molecule across a distance?

    <p>Free energy exchange</p> Signup and view all the answers

    What is the counterforce to diffusion that allows systems to reach homogeneity?

    <p>Frictional force exerted by viscosity</p> Signup and view all the answers

    What is the function of the diffusion coefficient related to?

    <p>Temperature/viscosity and solute radius</p> Signup and view all the answers

    What phenomenon occurs when a solution is allowed to stand unagitated and the force of gravity acts?

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

    What is the greater affect than gravity in ultracentrifugation?

    <p>Rotates at high speed (10,000 to 80,000 g)</p> Signup and view all the answers

    What does Fick’s 2nd Law of Diffusion explain?

    <p>The diffusion process in a given direction</p> Signup and view all the answers

    When does diffusion slow down according to Fick’s 2nd Law of Diffusion?

    <p>When the concentration gradient decreases</p> Signup and view all the answers

    What is the goal of establishing sink conditions in diffusion?

    <p>To drive the concentration gradient to a constant</p> Signup and view all the answers

    What is the method used to determine the diffusion coefficient in a two-chamber vessel separated by a porous membrane?

    <p>Calibrating with a compound whose diffusion coefficient is known</p> Signup and view all the answers

    What is the mass transfer of molecules based on a concentration gradient known as?

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

    What is the equation for flux (J) in the determination of diffusion coefficient?

    <p>$J = -Ddc/dx$</p> Signup and view all the answers

    What does passive diffusion continue as long as is maintained?

    <p>The diffusion layer (h)</p> Signup and view all the answers

    What is the primary objective of dissolution rate studies?

    <p>Assessment of oral drug absorption under physiological conditions</p> Signup and view all the answers

    Which factor can potentially increase the dissolution rate of poorly water-soluble drugs?

    <p>Bile salts forming micelles</p> Signup and view all the answers

    What is the role of excipients in drug formulations?

    <p>They can increase or decrease the aqueous solubility of drugs</p> Signup and view all the answers

    What is the relationship between particle size and dissolution rate?

    <p>Micronization of particles increases the dissolution rate</p> Signup and view all the answers

    What is the most important quality control test for many pharmaceutical preparations?

    <p>Dissolution testing</p> Signup and view all the answers

    What does the process of drug dissolution involve?

    <p>Wetting, penetration of the solvent, swelling, disintegration, and dissolution of individual drug particles</p> Signup and view all the answers

    What are in vitro tests used for in the pharmaceutical industry?

    <p>Drug quality control</p> Signup and view all the answers

    What does the Biopharmaceutical Classification System (BCS) utilize for dissolution fluid?

    <p>250mL of dissolution fluid</p> Signup and view all the answers

    What happens to the thickness of the diffusion layer over time?

    <p>It decreases, leading to an increase in the intrinsic dissolution rate</p> Signup and view all the answers

    What conditions are reported for the gastrointestinal (GI) tract after ingesting 250mL of water?

    <p>Stomach and intestinal pH levels</p> Signup and view all the answers

    What is the primary influence on the dissolution rate of drugs?

    <p>pH of the dissolution medium</p> Signup and view all the answers

    What is the role of agitation in dissolution testing?

    <p>It influences the dissolution rate</p> Signup and view all the answers

    What does Fick's First Law of Diffusion state?

    <p>The rate of diffusion is proportionate to concentration gradient, cross-sectional area, and diffusion coefficient.</p> Signup and view all the answers

    What does the diffusion coefficient (D) represent?

    <p>The amount of solute diffusing across 1 cm$^2$ in 1 second.</p> Signup and view all the answers

    What is the equation for flux (J) in the determination of diffusion coefficient?

    <p>J = -D(dw/dt)</p> Signup and view all the answers

    What is the function of the diffusion coefficient related to?

    <p>The specific solvent and specific temperature.</p> Signup and view all the answers

    What is the approximate fasting pH range in the duodenum of the small intestine?

    <p>6.2-7.0</p> Signup and view all the answers

    What is the main buffer system in the small intestine?

    <p>Bicarbonate system</p> Signup and view all the answers

    What is the approximate bile salt/phospholipids ratio in the small intestine in the fasting state?

    <p>3:1</p> Signup and view all the answers

    What is the effective permeability (Peff) of the intestine for drug absorption?

    <p>10^-4 cm/s</p> Signup and view all the answers

    What is the approximate transit time of drug absorption in the stomach in the fasting state?

    <p>12 minutes</p> Signup and view all the answers

    Which BCS class of drugs may qualify for a waiver of in vivo bioavailability and bioequivalence studies?

    <p>Class I (high solubility-high permeability)</p> Signup and view all the answers

    What is the role of agitation in dissolution testing?

    <p>To enhance dissolution rate</p> Signup and view all the answers

    What is the approximate surface area of the intestine needed for sufficient oral absorption?

    <p>800 cm²</p> Signup and view all the answers

    What does the Biopharmaceutical Classification System (BCS) classify based on for oral drug absorption?

    <p>Combination of drug solubility and permeability</p> Signup and view all the answers

    What is the primary influence on the dissolution rate of drugs?

    <p>Drug solubility</p> Signup and view all the answers

    What is the main factor for oral drug absorption according to the text?

    <p>Combination of drug solubility and permeability</p> Signup and view all the answers

    What is the primary objective of dissolution rate studies?

    <p>To assess the rate of drug release from its dosage form</p> Signup and view all the answers

    What is the primary counterforce to diffusion that allows systems to reach homogeneity?

    <p>Frictional force exerted by viscosity of the solution</p> Signup and view all the answers

    What is the primary driving force for the transfer of one molecule across a distance?

    <p>Free energy exchange</p> Signup and view all the answers

    What does Fick’s 2nd Law of Diffusion explain?

    <p>How diffusion will cause a concentration change with respect to time</p> Signup and view all the answers

    What occurs when a solution is allowed to stand unagitated and the force of gravity acts?

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

    What is the method used to determine the diffusion coefficient in a two-chamber vessel separated by a porous membrane?

    <p>Flux (J) using the calibration value of A/h</p> Signup and view all the answers

    What does passive diffusion continue as long as is maintained?

    <p>The diffusion layer (h)</p> Signup and view all the answers

    What is the approximate transit time of drug absorption in the stomach in the fasting state?

    <p>1-2 hours</p> Signup and view all the answers

    What is the approximate fasting pH range in the duodenum of the small intestine?

    <p>1-2</p> Signup and view all the answers

    What is the primary goal of establishing sink conditions in diffusion?

    <p>To drive concentration gradient to a constant</p> Signup and view all the answers

    What is the primary distinction between ultracentrifugation and centrifugation?

    <p>Ultracentrifugation rotates at extremely high speed</p> Signup and view all the answers

    What is the primary factor that can alter the distribution of solute molecules in space during sedimentation and ultracentrifugation?

    <p>Added forces</p> Signup and view all the answers

    What is the equation used to determine the flux (J) in the determination of the diffusion coefficient?

    <p>$J = dw/dt = -Ddc/dx$</p> Signup and view all the answers

    What is the primary goal of dissolution rate studies?

    <p>Assessment of oral drug absorption under physiological conditions</p> Signup and view all the answers

    What factors can influence the dissolution rate of drugs?

    <p>Agitation, pH, solubility, and particle size</p> Signup and view all the answers

    What is the role of excipients in drug formulations?

    <p>They can increase or decrease the aqueous solubility of drugs</p> Signup and view all the answers

    What is the relationship between particle size and dissolution rate?

    <p>Micronization of particles increases the dissolution rate and oral absorption</p> Signup and view all the answers

    What is the approximate pH range in the small intestine?

    <p>6-7.4</p> Signup and view all the answers

    What are dissolution tests carried out under?

    <p>Simulated in vivo sink conditions</p> Signup and view all the answers

    What can bile salts do to enhance drug dissolution?

    <p>Form micelles, enhancing the solubility of lipophilic drugs</p> Signup and view all the answers

    What is the primary influence on the dissolution rate of drugs?

    <p>pH of the dissolution medium, solubility, and influence of excipients</p> Signup and view all the answers

    What is the approximate volume of dissolution fluid utilized by the Biopharmaceutical Classification System (BCS)?

    <p>250mL</p> Signup and view all the answers

    What is the approximate transit time of drug absorption in the stomach in the fasting state?

    <p>0.5-2 hours</p> Signup and view all the answers

    What is the approximate transit time of drug absorption in the intestines in the fasting state?

    <p>6-8 hours</p> Signup and view all the answers

    What is the approximate bile salt/phospholipids ratio in the small intestine?

    <p>2:1</p> Signup and view all the answers

    Study Notes

    Drug Dissolution and Factors Affecting Dissolution Rate

    • The process of drug dissolution is a kinetic process of solid particles going into solution, which is vital for determining the bioavailability of a drug in vivo.
    • In vitro tests are used for drug quality control, with dissolution testing being the most important quality control test for many pharmaceutical preparations.
    • Drug dissolution from a solid dosage form involves steps such as wetting, penetration of the solvent, swelling, disintegration, and dissolution of individual drug particles.
    • Dissolution tests are carried out under simulated in vivo sink conditions with constant replacement of the dissolution medium and specific apparatuses and protocols as described by the USP.
    • The primary objective of dissolution rate studies is the assessment of oral drug absorption under physiological conditions, and the Biopharmaceutical Classification System (BCS) utilizes 250mL of dissolution fluid.
    • Physiological conditions in the gastrointestinal (GI) tract after ingesting 250mL of water are reported, including stomach and intestinal pH levels.
    • Factors influencing drug dissolution rate include the diffusion layer thickness, agitation, pH, solubility, and the influence of excipients, surfactants, bile salts, particle size, and solid state properties.
    • The thickness of the diffusion layer decreases over time, leading to an increase in the intrinsic dissolution rate, and the dissolution rate depends on the way solid particles are scattered over the bottom of the vessels.
    • The pH of the dissolution medium, the solubility and dissolution of weak electrolytes and salts, and the influence of excipients can affect the dissolution rate of drugs.
    • Excipients in drug formulations can increase or decrease the aqueous solubility of drugs, with different effects from substances such as lactose, starch, lubricants, and surfactants.
    • Bile salts can form micelles, enhancing the solubility of lipophilic drugs and potentially increasing the dissolution rate of poorly water-soluble drugs.
    • Particle size and surface area have a direct relationship with the dissolution rate, with micronization of particles increasing the dissolution rate and oral absorption.

    Drug Dissolution and Factors Affecting Dissolution Rate

    • The process of drug dissolution is a kinetic process of solid particles going into solution, which is vital for determining the bioavailability of a drug in vivo.
    • In vitro tests are used for drug quality control, with dissolution testing being the most important quality control test for many pharmaceutical preparations.
    • Drug dissolution from a solid dosage form involves steps such as wetting, penetration of the solvent, swelling, disintegration, and dissolution of individual drug particles.
    • Dissolution tests are carried out under simulated in vivo sink conditions with constant replacement of the dissolution medium and specific apparatuses and protocols as described by the USP.
    • The primary objective of dissolution rate studies is the assessment of oral drug absorption under physiological conditions, and the Biopharmaceutical Classification System (BCS) utilizes 250mL of dissolution fluid.
    • Physiological conditions in the gastrointestinal (GI) tract after ingesting 250mL of water are reported, including stomach and intestinal pH levels.
    • Factors influencing drug dissolution rate include the diffusion layer thickness, agitation, pH, solubility, and the influence of excipients, surfactants, bile salts, particle size, and solid state properties.
    • The thickness of the diffusion layer decreases over time, leading to an increase in the intrinsic dissolution rate, and the dissolution rate depends on the way solid particles are scattered over the bottom of the vessels.
    • The pH of the dissolution medium, the solubility and dissolution of weak electrolytes and salts, and the influence of excipients can affect the dissolution rate of drugs.
    • Excipients in drug formulations can increase or decrease the aqueous solubility of drugs, with different effects from substances such as lactose, starch, lubricants, and surfactants.
    • Bile salts can form micelles, enhancing the solubility of lipophilic drugs and potentially increasing the dissolution rate of poorly water-soluble drugs.
    • Particle size and surface area have a direct relationship with the dissolution rate, with micronization of particles increasing the dissolution rate and oral absorption.

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    Description

    Test your knowledge of drug dissolution and factors affecting dissolution rate with this quiz. Explore the key steps involved in drug dissolution from solid dosage forms, the importance of in vitro dissolution testing, and the impact of factors such as pH, solubility, particle size, and excipients on drug dissolution rate. Gain insights into the role of bile salts, surfactants, and the Biopharmaceutical Classification System in assessing oral drug absorption.

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