Advantages and disadvantages of suspensions MCQs With Answer

Introduction: Pharmaceutical suspensions are dispersed systems where insoluble drug particles are uniformly distributed in a liquid vehicle. For B. Pharm students, understanding the advantages and disadvantages of suspensions is vital for designing stable, palatable, and bioavailable dosage forms. Key concepts include sedimentation, caking, flocculation and deflocculation, rheology (thixotropy, yield value), Stokes’ law, particle size control, wetting, zeta potential, and excipient selection (suspending agents, surfactants, preservatives). Advantages include improved chemical stability of hydrolyzable drugs, dose flexibility, and suitability for pediatric and depot formulations; disadvantages include physical instability, dose non-uniformity if not shaken, and bulkiness. This set covers practical formulation strategies and clinical considerations. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which is a key advantage of suspending a poorly soluble, hydrolyzable drug rather than formulating it as a solution?

• Faster onset of action than a solution
• Reduced chemical degradation by keeping most drug undissolved
• Eliminates the need for preservatives
• Improves drug taste by complete dissolution

Correct Answer: Reduced chemical degradation by keeping most drug undissolved

Q2. Why are oral suspensions often preferred for pediatric patients?

• They never require shaking before dosing
• They completely eliminate bitter taste
• They allow dose flexibility and can mask bitterness by minimizing drug in solution
• They are always more stable than tablets

Correct Answer: They allow dose flexibility and can mask bitterness by minimizing drug in solution

Q3. A common disadvantage of deflocculated suspensions during storage is:

• Rapid redispersion after settling
• Formation of a hard cake that is difficult to redisperse
• No sedimentation occurs
• Very high sedimentation volume

Correct Answer: Formation of a hard cake that is difficult to redisperse

Q4. According to Stokes’ law, which change will most effectively decrease sedimentation rate?

• Increase particle size and decrease viscosity
• Decrease particle size and decrease viscosity
• Decrease particle size and increase vehicle viscosity
• Increase density difference between particle and medium

Correct Answer: Decrease particle size and increase vehicle viscosity

Q5. Which characteristic best describes a flocculated suspension?

• Rapid sedimentation but easy redispersion with a high sedimentation volume
• Slow sedimentation with hard caking
• No need for shaking before dosing
• Zero zeta potential at all times

Correct Answer: Rapid sedimentation but easy redispersion with a high sedimentation volume

Q6. A potential drawback of controlled flocculation is:

• Increased sedimentation rate leading to faster settling
• Irreversible caking
• Complete prevention of sedimentation
• Reduced physical stability due to Ostwald ripening

Correct Answer: Increased sedimentation rate leading to faster settling

Q7. The primary purpose of adding a wetting agent to a suspension is to:

• Increase the drug’s solubility
• Reduce contact angle to displace air and improve particle wetting
• Decrease viscosity of the vehicle
• Increase zeta potential magnitude

Correct Answer: Reduce contact angle to displace air and improve particle wetting

Q8. For pourable oral suspensions, the most desirable rheological behavior of the vehicle is:

• Newtonian with no yield value
• Dilatant (shear-thickening)
• Pseudoplastic with a slight yield value and thixotropy
• Purely elastic solid

Correct Answer: Pseudoplastic with a slight yield value and thixotropy

Q9. What is a clinical advantage of depot intramuscular suspensions?

• Immediate onset of action
• No need for aseptic processing
• Prolonged drug release for sustained therapy
• Suitable for intravenous administration

Correct Answer: Prolonged drug release for sustained therapy

Q10. Why are suspensions generally unsuitable for intravenous administration?

• Risk of embolism due to particulate matter
• They are always hypertonic
• They cannot be sterilized
• They have zero bioavailability

Correct Answer: Risk of embolism due to particulate matter

Q11. Ostwald ripening in suspensions leads to:

• Decrease in particle size uniformity without growth
• Growth of larger crystals at the expense of smaller ones, risking caking
• Improved redispersibility
• Immediate dissolution of particles

Correct Answer: Growth of larger crystals at the expense of smaller ones, risking caking

Q12. Reducing the magnitude of zeta potential by adding electrolytes typically:

• Increases repulsion and prevents flocculation
• Promotes controlled flocculation by decreasing electrical double-layer repulsion
• Eliminates the need for suspending agents
• Causes particles to dissolve

Correct Answer: Promotes controlled flocculation by decreasing electrical double-layer repulsion

Q13. A dosing-related disadvantage of oral suspensions is:

• Potential dose variability if the bottle is not adequately shaken
• Irreversible chemical degradation upon shaking
• No possibility of dose adjustment
• Inability to mask taste

Correct Answer: Potential dose variability if the bottle is not adequately shaken

Q14. Which strategy helps reduce sedimentation by minimizing density difference between dispersed phase and vehicle?

• Use of volatile solvents
• Adding density modifiers like glycerin or sorbitol to the vehicle
• Decreasing viscosity with alcohol
• Using only nonionic surfactants

Correct Answer: Adding density modifiers like glycerin or sorbitol to the vehicle

Q15. Considering the same drug, which order of onset of action is generally correct?

• Solution > Suspension > Tablet
• Suspension > Solution > Tablet
• Tablet > Suspension > Solution
• All have identical onset

Correct Answer: Solution > Suspension > Tablet

Q16. For ophthalmic suspensions, an appropriate particle size to minimize irritation and blockage is typically:

• 50–100 μm
• < 10 μm
• 100–200 μm
• 1–2 mm

Correct Answer: < 10 μm

Q17. Which interaction can reduce preservative efficacy in suspensions?

• Increased particle sedimentation
• Adsorption or partitioning of preservative onto particles or polymers
• Use of thixotropic vehicles
• Decrease in particle size

Correct Answer: Adsorption or partitioning of preservative onto particles or polymers

Q18. The best method to disperse hydrophobic drug powders during suspension preparation is to:

• Heat the powder to increase solubility
• Pre-wet with a suitable wetting agent to lower contact angle
• Add more preservative
• Use only high-speed milling without surfactant

Correct Answer: Pre-wet with a suitable wetting agent to lower contact angle

Q19. Which is a palatability-related limitation of oral suspensions?

• They always taste sweet regardless of drug
• Residual dissolved fraction can contribute to bitterness despite dispersion
• Flavoring agents cannot be used
• Viscosity prevents taste perception

Correct Answer: Residual dissolved fraction can contribute to bitterness despite dispersion

Q20. Sedimentation volume (F) is defined as:

• Ratio of ultimate sediment volume (Vu) to original suspension volume (Vo)
• Ratio of particle size to viscosity
• Product of density and gravity
• Viscosity divided by shear rate

Correct Answer: Ratio of ultimate sediment volume (Vu) to original suspension volume (Vo)

Q21. When formulating a cationic drug suspension, which suspending agent minimizes ionic incompatibility risk?

• Sodium carboxymethylcellulose (anionic)
• Alginates (anionic)
• Hydroxypropyl methylcellulose (nonionic)
• Sodium polystyrene sulfonate (strongly anionic)

Correct Answer: Hydroxypropyl methylcellulose (nonionic)

Q22. Why is thixotropy advantageous in suspensions?

• It permanently increases viscosity under shear
• It allows shear-thinning during shaking/pouring and rebuilds structure at rest to resist sedimentation
• It ensures zero yield value
• It eliminates the need for shaking

Correct Answer: It allows shear-thinning during shaking/pouring and rebuilds structure at rest to resist sedimentation

Q23. A practical disadvantage of suspensions compared to solid dosage forms is:

• Lower dose flexibility
• Bulkier packaging and reduced portability
• Inability to flavor the product
• Always higher cost

Correct Answer: Bulkier packaging and reduced portability

Q24. To inhibit crystal growth in a suspension (limit Ostwald ripening), a formulator might add:

• Sodium chloride only
• Polymeric crystal growth inhibitors like PVP or HPMC
• Strong acids
• Only more preservative

Correct Answer: Polymeric crystal growth inhibitors like PVP or HPMC

Q25. To reduce sedimentation rate without altering particle size, which excipient level would you most likely increase?

• Ethanol
• Xanthan gum (suspending agent)
• Sodium chloride
• Flavor

Correct Answer: Xanthan gum (suspending agent)

Q26. Zeta potential in suspensions is commonly measured by:

• Nuclear magnetic resonance
• Electrophoretic light scattering (microelectrophoresis)
• Differential scanning calorimetry
• X-ray diffraction

Correct Answer: Electrophoretic light scattering (microelectrophoresis)

Q27. Which patient counseling point is essential for safe and effective use of oral suspensions?

• Do not refrigerate after opening
• Measure dose with a household spoon
• Shake well before each use to ensure dose uniformity
• Swallow without shaking to avoid foam

Correct Answer: Shake well before each use to ensure dose uniformity

Q28. A benefit of supplying antibiotics as dry powders for suspension (to be reconstituted) is:

• Improved shelf-life by avoiding hydrolytic degradation during storage
• Immediate readiness for dosing without reconstitution
• No need for preservatives after reconstitution
• Elimination of sedimentation after reconstitution

Correct Answer: Improved shelf-life by avoiding hydrolytic degradation during storage

Q29. For topical dermatologic suspensions (lotions), a therapeutic advantage is:

• Guaranteed systemic delivery
• Prolonged residence at the application site with reduced systemic exposure
• Complete absence of sedimentation
• No need for viscosity modifiers

Correct Answer: Prolonged residence at the application site with reduced systemic exposure

Q30. For wetting hydrophobic drug particles in aqueous suspensions, a suitable nonionic surfactant HLB range is typically:

• 1–3
• 4–6
• 7–9
• 15–18

Correct Answer: 7–9

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