Pharmaceutics: Dispersed Systems
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Questions and Answers

What is an example of a colloidal dispersion that is used for coating over tablets?

  • Froth
  • Milk
  • Gelatin (correct)
  • Sponge

    • Lyophilic colloids are thermodynamically unstable.

    False

    What type of colloids are liposomes categorized as?

    Lyophobic colloids

    Colloids such as __________ are better absorbed compared to coarse dispersion of sulfur.

    <p>Colloidal sulfur</p> Signup and view all the answers

    Which of the following describes a gas in a liquid dispersion?

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

    Match the following types of colloidal dispersions with their examples:

    <p>Emulsion = Milk Sol = Paint Gel = Cheese Foam = Froth</p> Signup and view all the answers

    The solubilization of phenobarbital can occur in micellar solutions.

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

    Colloidal dimensions allow targeting of drugs to specific _________ in the body.

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

    Which statement is true regarding lyophilic colloids?

    <p>They are thermodynamically stable.</p> Signup and view all the answers

    Name one type of colloidal dispersion that consists of a solid phase dispersed in a liquid medium.

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

    What is a hydrosol often known as when water is the dispersing medium?

    <p>Hydrophilic colloid</p> Signup and view all the answers

    Lyophobic colloids have a strong attraction with their dispersion medium.

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

    Name one example of a hydrophilic colloid.

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

    Lyophobic colloids are also known as __________ sols.

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

    Match the following types of colloids with their characteristics:

    <p>Hydrophilic colloids = Stabilized by attraction to water Lyophobic colloids = Thermodynamically unstable Amphiphilic colloids = Form micelles in polar and non-polar liquids Irreversible sols = Difficult to reconstitute after precipitation</p> Signup and view all the answers

    What type of surfactants are normally used for internal use?

    <p>Nonionic surfactants</p> Signup and view all the answers

    Increasing the concentration of surfactants always leads to better micelle formation.

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

    What's one benefit of micellar solubilization in drug formulation?

    <p>Prevention of drug decomposition</p> Signup and view all the answers

    Which process involves removing ions or molecules from a colloidal dispersion through a semipermeable membrane?

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

    Lyophobic colloids, like gold and silver, are __________ in water.

    <p>solvent-hating</p> Signup and view all the answers

    Which property describes amphiphilic colloids?

    <p>Form micelles in both polar and non-polar environments</p> Signup and view all the answers

    Ultrafiltration is a fast process that does not require any external force.

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

    What is the primary purpose of dialysis in colloidal systems?

    <p>To remove ions or molecules from a colloidal dispersion.</p> Signup and view all the answers

    In electrodialysis, the diffusion of ions is enhanced by applying a _____ across the membrane.

    <p>potential difference</p> Signup and view all the answers

    Match the colloidal separation processes with their descriptions:

    <p>Dialysis = Removal of small particles through a semipermeable membrane Electrodialysis = Ion diffusion enhanced by electric potential Ultrafiltration = Separation of colloidal particles using pressure Centrifugation = Use of centrifugal force to separate components</p> Signup and view all the answers

    What happens to the drug's release when the concentration of surfactant is higher?

    <p>It delays release and reduces absorption.</p> Signup and view all the answers

    Nonionic impurities can be separated using electrodialysis.

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

    What type of filter is used in ultrafiltration?

    <p>Modified filter papers.</p> Signup and view all the answers

    The process in which colloidal particles are retained on a filter paper and dispersed in a pure medium is called _____ .

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

    Which of the following statements is true about dialysis?

    <p>It relies on diffusion through a membrane.</p> Signup and view all the answers

    Which type of dispersion is characterized by particle sizes less than 1nm?

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

    Coarse dispersions can pass through filter paper.

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

    What is the Tyndall effect associated with?

    <p>Colloidal dispersions</p> Signup and view all the answers

    Particles in a coarse dispersion are typically larger than _____ µm.

    <p>0.5</p> Signup and view all the answers

    Match the type of dispersion with its characteristic:

    <p>Molecular dispersions = Particles do not settle even on ultracentrifugation Colloidal dispersions = Particles are visible by electron microscope Coarse dispersions = Particles settle down under gravity Colloidal silver sols = Used as germicidal agent</p> Signup and view all the answers

    What is a common example of a molecular dispersion?

    <p>Ordinary ions</p> Signup and view all the answers

    Colloidal dispersions can diffuse rapidly.

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

    Name one therapeutic application of colloidal systems.

    <p>Silver colloid used as germicidal</p> Signup and view all the answers

    Particles in colloidal dispersions are _____ by ordinary microscope.

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

    Which of the following describes coarse dispersions?

    <p>Do not pass through semipermeable membranes</p> Signup and view all the answers

    Study Notes

    Dispersed Systems

    • Dispersed systems are composed of particulate matter (dispersed phase) dispersed within a continuous phase (dispersion medium).
    • Classification is based on particle size:
      • Molecular dispersions
      • Coarse dispersions
      • Colloidal dispersions

    Molecular Dispersions

    • Defined by particle size less than 1 nm.
    • Characterized by invisibility under an electron microscope and no light scattering.
    • Can pass through filter paper and semipermeable membranes.
    • Particles do not settle and show rapid diffusion.
    • Examples include ordinary ions and glucose.

    Coarse Dispersions

    • Defined by particle size greater than 0.5 µm.
    • Visible under a regular microscope and do not pass through filter paper or semipermeable membranes.
    • Particles settle under gravity and do not diffuse.
    • Examples include emulsions, suspensions, and red blood cells.

    Colloidal Dispersions

    • Defined by particle size ranging from 1 nm to 0.5 µm.
    • Invisible under a standard microscope but visible under an electron microscope.
    • Scatter light and demonstrate the Tyndall effect.
    • Can pass through filter paper but not through semipermeable membranes.
    • Particles can settle by centrifugation and diffuse slowly.
    • Common example includes colloidal silver sols.

    Pharmaceutical Applications of Colloids

    • Used therapeutically, e.g., Silver colloid as a germicide and Copper colloid for anticancer treatment.
    • Enhance absorption, such as colloidal sulfur being absorbed more effectively than coarse sulfur dispersion.
    • Improve solubility for drugs like salicylic acid in micellar solutions.
    • Provide stability, e.g., colloidal gelatin used for tablet coatings.
    • Facilitate drug targeting, e.g., liposomes targeting the liver and spleen.

    Classification of Colloidal Dispersions

    • Based on physical state and interaction nature:
      • Physical state:
        • Liquid-liquid: Emulsions (e.g., milk)
        • Solid-liquid: Sols (e.g., paints)
        • Gas-liquid: Foams (e.g., froth)
        • Solid-solid: Solid sols (e.g., colored glasses)
        • Liquid-solid: Gels (e.g., cheese)
        • Gas-solid: Solid foams (e.g., sponges)
        • Liquid-gas: Aerosols (e.g., fog)
        • Solid-gas: Solid aerosols (e.g., dust)

    Nature of Interaction

    • Lyophilic Colloids (solvent-attracting)

      • High affinity for solvent, easily prepared, and thermodynamically stable.
      • Examples include acacia and gelatin in water.

    • Lyophobic Colloids (solvent-hating)

      • Minimal attraction to solvent, thermodynamically unstable and easily precipitated.
      • Examples include gold and silver in water.

    • Association/Amphiphilic Colloids

      • Hydrocarbon chains form micelles with polar heads facing solvent.
      • Micellar solubilization allows for solubilization of poorly water-soluble drugs.

    Formulation Factors for Solubilized Systems

    • Surfactant type: Nonionic surfactants for internal use; ionic for external.
    • Surfactant concentration: Must be optimal to form micelles and prevent drug precipitation.

    Purification of Colloidal Systems

    • Dialysis: Removes small ions/molecules from a colloidal dispersion via a semipermeable membrane.
    • Electrodialysis: Enhances ion diffusion by applying a potential difference across the membrane.
    • Ultrafiltration: Retains colloidal particles on ultrafilter paper; pressure or suction can be used to accelerate filtration.

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    Description

    This quiz focuses on the concept of dispersed systems within the context of physical pharmacy. Learn about the classifications and characteristics of molecular, coarse, and colloidal dispersions. Test your knowledge on how these systems operate and their relevance in pharmaceuticals.

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