Pharmaceutical Technology II: Dissolution
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Questions and Answers

What is dissolution?

  • The process of a solid dissolving into a gas
  • The process of solid particles becoming smaller
  • The process of a solid changing its shape
  • The process by which molecules of a solid substance form a one-phase, homogeneous, molecular mixture with a solvent (correct)

    • Who modified Wagner's scheme for the dissolution of solid dosage forms?

  • Whitney
  • Carstensen (correct)
  • Noyes
  • Saaka

    • What is the name of the equation that describes the factors affecting dissolution rate?

  • Carstensen's equation
  • Saaka's equation
  • Wagner's equation
  • Noyes-Whitney equation (correct)

    • What is the purpose of dissolution testing?

    <p>To measure the rate of drug release</p> Signup and view all the answers

    What is the name of the department where Yussif Saaka teaches?

    <p>Department of Pharmaceutics</p> Signup and view all the answers

    What is the result of the dissolution process?

    <p>Drug in solution</p> Signup and view all the answers

    What is the name of the university where Yussif Saaka teaches?

    <p>University of Health and Allied Sciences</p> Signup and view all the answers

    What is the name of the course where dissolution is taught?

    <p>SOPH 331 Pharmaceutical Technology II</p> Signup and view all the answers

    What is the first step in Carstensen's scheme of drug dissolution?

    <p>Initial mechanical lag</p> Signup and view all the answers

    According to Carstensen, what controls the liquid access to the solid surface?

    <p>Wetting of the solid dosage form surface</p> Signup and view all the answers

    What is the rate-limiting step for absorption through the GI membrane for freely water-soluble drugs?

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

    What is the primary rate-limiting step for the absorption of poorly water-soluble drugs?

    <p>Dissolution of the undissolved drug</p> Signup and view all the answers

    What is the definition of drug release?

    <p>The process by which a drug leaves a drug product and is subjected to absorption, distribution, metabolism and excretion</p> Signup and view all the answers

    What type of kinetics is characterized by a constant drug release from a drug delivery device?

    <p>Zero-order kinetics</p> Signup and view all the answers

    What is the result of wetting of the solid dosage form surface?

    <p>Decreased contact angles</p> Signup and view all the answers

    What is the primary reason for the importance of wetting in the dissolution process?

    <p>It controls the liquid access to the solid surface</p> Signup and view all the answers

    What is the primary rate-limiting step for drug absorption in Class 2 drugs?

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

    Which class of drugs is most likely to have significant problems with oral drug delivery?

    <p>Class 4</p> Signup and view all the answers

    What is the primary condition for granting biowaiver for BCS Class 1 drug products?

    <p>The drug product is rapidly dissolving</p> Signup and view all the answers

    In which of the following media is dissolution testing for biowaiver performed?

    <p>0.1 N HCl or Simulated Gastric Fluid USP without enzymes</p> Signup and view all the answers

    What is the definition of a rapidly dissolving drug product for biowaiver?

    <p>Not less than 85% of the labeled amount of the drug substance dissolves within 30 minutes</p> Signup and view all the answers

    For which class of drugs is the correlation of in-vivo results with dissolution tests most accurate?

    <p>Class 2</p> Signup and view all the answers

    Under what conditions is permeability the rate-controlling step for drug absorption?

    <p>For Class 3 drugs with high solubility and low permeability</p> Signup and view all the answers

    What is the primary advantage of IVIVC for Class 1 drugs formulated as extended-release products?

    <p>Absorption is controlled by the availability of the drug in the GIT</p> Signup and view all the answers

    What type of apparatus is suggested by the USP for chewable tablets, except for ampicillin chewable tablets?

    <p>Paddle method</p> Signup and view all the answers

    What type of dissolution testing method is commonly used for buccal tablets?

    <p>USP apparatus 2</p> Signup and view all the answers

    What type of apparatus is frequently used for suspensions?

    <p>USP apparatus 2</p> Signup and view all the answers

    What is the typical way of testing suppositories?

    <p>Placing the suppository in a dialyzing bag made of special membrane or cellophane material</p> Signup and view all the answers

    What type of dissolution testing method is used for extended-release dosage forms?

    <p>Multipoint dissolution profiles in three other media</p> Signup and view all the answers

    What is the suggested duration for the acid stage of dissolution testing for delayed-release dosage forms?

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

    What is the pH range of the buffer media used for the buffer stage of dissolution testing for delayed-release dosage forms?

    <p>pH 4.5 - 7.5</p> Signup and view all the answers

    What is the purpose of using a dialyzing bag made of special membrane or cellophane material for suppositories?

    <p>To contain the suppository during dissolution testing</p> Signup and view all the answers

    What is the main advantage of using a basket with slots in dissolution testing?

    <p>It prevents blockade of the mesh and allows for testing of suppositories with low specific gravity</p> Signup and view all the answers

    What is the purpose of the synthetic membrane in the Franz cell system?

    <p>To separate the dosage form from the sampling fluid</p> Signup and view all the answers

    What is placed in the open donor chamber of the diffusion cell?

    <p>Dosage form</p> Signup and view all the answers

    What is monitored in the diffusion cell system?

    <p>The diffusion of the drug from the topical product</p> Signup and view all the answers

    What is the purpose of the receptor fluid in the diffusion cell system?

    <p>To collect samples for assaying the drug concentration</p> Signup and view all the answers

    What type of dosage forms are typically tested using the Franz cell system?

    <p>Topical dosage forms</p> Signup and view all the answers

    Study Notes

    Objectives

    • Understand the principles of dissolution
    • Understand drug-release kinetics
    • Understand the Noyes-Whitney equation
    • Understand factors affecting dissolution rate
    • Understand dissolution testing
    • Understand USP apparatuses and dosage form-specific testing

    Introduction to Dissolution

    • Dissolution is the process by which molecules of a solid substance form a one-phase, homogeneous, molecular mixture with a solvent
    • Wagner's scheme proposes the following processes involved in the dissolution of solid dosage forms:
      • Disintegration
      • Deaggregation
      • Dissolution
    • Carstensen's modified scheme includes:
      • Initial mechanical lag
      • Wetting of the dosage form
      • Penetration of the dissolution medium into the dosage form
      • Disintegration
      • Deaggregation of the dosage form and dislodgement of the granules
      • Dissolution and occlusion of some particles of the drug

    Dissolution Rate-Limiting Steps

    • The rate of drug dissolution can become the only rate-limiting step before it appears in the blood
    • When the dosage form is placed into the GIT in solid form, there are two possible rate-limiting steps:
      • The solid must first dissolve, and the drug in solution must then pass through the gastrointestinal (GI) membrane
      • The rate of absorption of poorly water-soluble drugs will be limited by the rate of dissolution of the undissolved drug or disintegration of dosage form

    Drug Release Kinetics

    • Zero-order kinetics: constant drug release from a drug delivery device (i.e., amount of drug released per unit of time is constant)

    IVIVC (In Vivo/In Vitro Correlation)

    • Correlation of in-vivo results with dissolution tests is most accurate for Class 2 drugs
    • For Class 1 drugs, good IVIVCs are obtained when the drug is formulated as an extended-release product
    • IVIVC is not possible for Class 4 drugs due to significant problems for oral drug delivery

    Dissolution of Dosage Forms

    • Immediate release, solid oral: biowaiver may be granted for BCS Class 1 drug products for bioequivalence studies, if the drug product is rapidly dissolving
    • Powders: dissolution testing can be performed using paddle method or flow-through cell method
    • Dosage forms for the oral cavity: sublingual tablets, buccal tablets, and chewable tablets have specific dissolution testing methods
    • Suspensions: USP Apparatus 2 is frequently used
    • Modified-release: extended-release and delayed-release dosage forms have specific dissolution testing requirements
    • Suppositories: typically, the suppository is placed in a dialyzing bag made of special membrane or cellophane material
    • Topical dosage forms (creams, ointments, gels): an open chamber diffusion cell system, such as a Franz cell system, is used

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    Description

    This quiz covers the principles of dissolution, drug-release kinetics, and the Noyes-Whitney equation in pharmaceutical technology. Understand the key concepts and factors affecting dissolution in pharmaceutics.

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