Pharmaceutical Suspensions Quiz
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Questions and Answers

What is the primary role of wetting agents in a suspension?

  • To enhance the flavor of the liquid medium
  • To increase the particle size of the solid
  • To stabilize the suspension against gravitational sedimentation
  • To reduce interfacial tension between solid particles and liquid medium (correct)

    • Which of the following wetting agents is specifically noted for parenteral use?

  • Glycerol
  • Sodium lauryl sulfate
  • Pluronics (correct)
  • Acacia

    • What is a disadvantage of using surfactants as wetting agents?

  • They can increase the solubility of drugs.
  • They facilitate faster drug absorption.
  • They decrease interfacial tension.
  • They may cause excessive foaming. (correct)

    • What effect do trivalent ions have when added to a flocculated suspension?

    <p>They assist in forming a flocculated system.</p> Signup and view all the answers

    Which hydrophilic polymer is NOT listed among those used as wetting agents?

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

    How do solvents like glycerol contribute to wetting in a suspension?

    <p>By reducing liquid/air interfacial tension</p> Signup and view all the answers

    When might the use of excessive electrolyte in a suspension lead to problems?

    <p>It may cause charge reversal on the particles.</p> Signup and view all the answers

    What is the function of hydrophilic polymers when added to a solid in a liquid medium?

    <p>To impart a hydrophilic character to the solid</p> Signup and view all the answers

    What is the maximum concentration of Carbapol that can be used mainly for external applications?

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

    How do hydrated silicates like Bentonite need to be processed prior to use in external preparations?

    <p>They should be sterilized.</p> Signup and view all the answers

    Which of the following cellulose derivatives is used as a suspending agent?

    <p>Microcrystalline cellulose</p> Signup and view all the answers

    What is the potential issue arising from high concentrations of sweetening agents in a suspension?

    <p>Newtonian properties affecting rheological characteristics</p> Signup and view all the answers

    Which suspending agent can be used in both internal and external applications?

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

    What role do buffers play in suspension formulations?

    <p>Maintain chemical stability and tonicity</p> Signup and view all the answers

    Which of the following substances can be used as humectants in suspension formulations?

    <p>Propylene glycol</p> Signup and view all the answers

    What is the purpose of preservatives in suspension formulations?

    <p>Prevent the growth of microorganisms</p> Signup and view all the answers

    What is the effect of non-ionic surfactants on particle charge density?

    <p>They have little effect on the charge density.</p> Signup and view all the answers

    What happens to the positive zeta potential when monobasic potassium phosphate is added to bismuth subnitrate particles?

    <p>It decreases due to adsorption of negatively charged phosphate anions.</p> Signup and view all the answers

    Which statement correctly explains the correlation between zeta potential and sedimentation volume?

    <p>Sedimentation volume increases with a decrease in zeta potential.</p> Signup and view all the answers

    What type of agent is dibasic potassium phosphate when used with bismuth subnitrate suspension?

    <p>Flocculating agent.</p> Signup and view all the answers

    Which of the following polymeric flocculating agents creates a gel-like network in the dispersed phase?

    <p>Alginates, cellulose derivatives, and starch.</p> Signup and view all the answers

    What occurs to the sedimentation volume when the zeta potential becomes sufficiently negative?

    <p>It starts to decrease, indicating higher flocculation.</p> Signup and view all the answers

    Why does acacia gum become acidic upon storage?

    <p>Due to enzyme activity causing oxidation.</p> Signup and view all the answers

    What is a disadvantage of sodium alginate when used in dispersions?

    <p>It has an anionic character that causes incompatibility with cationic materials.</p> Signup and view all the answers

    What happens when the sedimentation volume 'F' is equal to 1?

    <p>The final sediment volume is equal to the original suspension volume.</p> Signup and view all the answers

    How is the degree of flocculation 'β' calculated?

    <p>β = F / Fα</p> Signup and view all the answers

    What is the likely result of using large particles in ophthalmic suspension?

    <p>A gritty texture that may irritate the eyes.</p> Signup and view all the answers

    What does a sedimentation volume 'F' greater than 1 indicate?

    <p>The sediment is flocculated with a loose structure.</p> Signup and view all the answers

    Which is NOT a method of preparing suspensions?

    <p>Increasing the drug's temperature continuously</p> Signup and view all the answers

    What parameter is considered more fundamental than sedimentation volume in suspension analysis?

    <p>Degree of Flocculation 'β'</p> Signup and view all the answers

    What term describes the final sediment volume of deflocculated suspension?

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

    What is the outcome of particle size growth during storage of a drug?

    <p>Crystallization and increased particle size</p> Signup and view all the answers

    Study Notes

    Pharmaceutical Suspension

    • Suspensions are pharmaceutical preparations where solid particles are dispersed in a liquid medium
    • Sedimentation parameters are used to assess suspension stability.
      • Sedimentation volume (F): The ratio of final sediment volume (Vf) to the original suspension volume (Vo). A value of F < 1 indicates the final sediment volume is less than the original suspension volume. F = 1 indicates the final sediment volume equals the original suspension volume. If F > 1, the final sediment volume exceeds the original suspension volume.
      • Degree of flocculation (β): A more fundamental parameter relating the volume of flocculated sediment to a deflocculated system. It is calculated as β = Ff/Fα = Vf/Vα, where Fα and Vα represent the sedimentation volume and final sediment volume of a deflocculated system, respectively.

    Preparation of Suspensions

    • Particle Size Control:

      • Large particles (greater than 5 µm) in ophthalmic suspensions cause irritation.
      • Large particles in parenteral suspensions can block needles.
      • Changes in temperature can cause drug crystallization, increasing particle size during storage. Drug solubility can be affected, and smaller particles may have higher solubility than larger ones.

    • Use of Wetting Agents:

      • Wetting agents reduce interfacial tension between solid particles and liquid medium.
      • This allows displacement of air from the solid surfaces.
      • Adequate wetting of the particles throughout the liquid is achieved.

    • Types of Wetting Agents:

      • Surfactants (HLB value 7-9) at concentrations of up to 0.1%
        • Tweens and Spans (oral use)
        • Sodium lauryl sulfate, Sodium dioctylsulphosuccinate (external use)
        • Tweens, Pluronics, Lecithin (parenteral use)
      • Disadvantages of surfactant use: excessive foaming, and the creation of a deflocculated system.

    • Hydrophilic Polymers and Hydrocolloids:

      • Materials that coat hydrophobic particles with a multimolecular layer, changing the solid from hydrophobic to hydrophilic
      • Examples: acacia, bentonite, tragacanth, alginates, cellulose derivatives.

    • Solvents:

      • Alcohol, glycerol, and glycols reduce liquid/air interfacial tension, aiding wetting in the dispersion medium

    Use of flocculating agents

    • Electrolytes:
      • Sodium salts of acetates, phosphates, and citrates are common electrolytes
      • Addition of electrolytes reduces zeta potential of dispersed particles, promoting flocculation
      • Flocculating ability of electrolytes depends on the valence of their counter-ions. Trivalent ions are more effective but less used due to toxicity. If hydrophilic polymers are present, these polymers may be precipitated if using trivalent ions
    • Surfactants:
      • Ionic surfactants help by neutralizing the charge on each particle
      • Non-ionic surfactants may affect the charge density of a particle but form a loose structure through linear configuration adsorption.

    Viscosity Modifiers (Suspending Agents)

    • Polysaccharides:
      • Acacia gum: acidification and potential oxidation-related problems
      • Tragacanth: better thickening agent than acacia
      • Alginates: Sodium alginate is the most used, but its anionic character makes it incompatible with heavy metals. Large increase in viscosity when calcium chloride is added
      • Starch: Sodium starch glycollate, a starch derivative, is used.
    • Water-soluble cellulose: Derivatives like Methyl cellulose, Hydroxyethyl cellulose, Carboxymethyl cellulose and Microcrystalline cellulose
    • Hydrated silicates: Bentonite, Magnesium aluminum silicate (Veegum), Hectorite, and Carbopol

    Other Formulation Additives in Suspensions

    • Buffers: Maintain chemical stability and control tonicity
    • Density Modifiers: Glycerol, propylene glycol, and sucrose keep suspension particles at a consistent density to prevent sedimentation.
    • Flavours, colours, and perfumes: Improve organoleptic properties of the suspension
    • Humectants: Prevent drying to skin after application
    • Preservatives: prevent microbial growth, e.g. heating dry powder, autoclaving
    • Sweeteners: Sorbitol, glycerol, or sucrose can negatively impact the suspension's properties and need to be accounted for

    Stability Testing of Suspension

    • Physical stability: Analyzed through sedimentation rate, initial/final volume, flocculation value, and redispersion ease.
    • Chemical stability: Assessed by concentration of active ingredients over time.

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    Pharmaceutical Suspension Lecture Notes PDF

    Description

    Test your knowledge on pharmaceutical suspensions, including their preparation and stability parameters. This quiz covers key concepts such as sedimentation volume and degree of flocculation. Challenge yourself to understand the intricacies of suspension formulations.

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