Formulation of suspensions MCQs With Answer is a focused study aid designed for B.Pharm students to master principles and practice of suspension dosage forms. This introduction covers key concepts such as suspension components, particle size reduction, wetting agents, suspending agents, flocculation vs deflocculation, rheology, Stoke’s law, zeta potential, preservatives, and stability testing. Emphasis is given to formulation strategies, manufacturing techniques (levigation, milling, homogenization), quality control parameters (sedimentation volume, redispersibility, viscosity, particle size distribution) and troubleshooting common stability issues. Keywords: suspension formulation, B.Pharm, wetting, flocculation, suspending agents, rheology, stability, preservatives, redispersibility, particle size. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. What is the primary purpose of a wetting agent in suspension formulation?
- To increase the pH of the dispersion medium
- To reduce interfacial tension and displace air from particle surfaces
- To act as a preservative for microbial control
- To increase sedimentation rate
Correct Answer: To reduce interfacial tension and displace air from particle surfaces
Q2. Which parameter best describes the resistance of a suspension to flow under applied stress?
- Surface tension
- Viscosity
- Redispersibility
- Sedimentation volume
Correct Answer: Viscosity
Q3. Stoke’s law relates sedimentation rate to which combination of factors?
- Particle size, temperature, and preservative concentration
- Particle size, density difference between particle and medium, and viscosity of medium
- Contact angle, zeta potential, and ionic strength
- pH, osmolarity, and total solids
Correct Answer: Particle size, density difference between particle and medium, and viscosity of medium
Q4. Which suspending agent is a natural gum commonly used in oral suspensions?
- Carboxymethyl cellulose (CMC)
- Xanthan gum
- Tragacanth
- Polysorbate 80
Correct Answer: Tragacanth
Q5. Flocculated suspensions are characterized by which property compared to deflocculated systems?
- Slower sedimentation and cake formation
- Faster sedimentation but easily redispersible loose sediments
- Formation of hard, compact cakes
- Complete prevention of sedimentation
Correct Answer: Faster sedimentation but easily redispersible loose sediments
Q6. Which measurement quantifies the ratio of sediment volume to original volume of suspension?
- Degree of flocculation
- Sedimentation volume (F)
- Viscosity index
- Zeta potential value
Correct Answer: Sedimentation volume (F)
Q7. Which stabilization mechanism involves adsorbed polymers creating a physical barrier to particle aggregation?
- Electrostatic stabilization
- Steric stabilization
- Flocculation
- Osmotic stabilization
Correct Answer: Steric stabilization
Q8. Zeta potential is an indicator of which aspect important for suspension stability?
- Viscosity of continuous phase
- Electrostatic repulsion between particles
- Rate of oxidation of drug
- Molecular weight of suspending agent
Correct Answer: Electrostatic repulsion between particles
Q9. Which of the following is a common method for particle size reduction in suspension manufacture?
- Centrifugation
- Levigation with a liquid vehicle
- Lyophilization
- Titration
Correct Answer: Levigation with a liquid vehicle
Q10. Which preservative is often used in aqueous pharmaceutical suspensions for antimicrobial protection?
- Tragacanth
- Parabens (methylparaben)
- Sodium chloride
- Magnesium stearate
Correct Answer: Parabens (methylparaben)
Q11. Which rheological behavior is desirable for oral suspensions to allow pouring yet maintain suspended particles at rest?
- Newtonian
- Pseudoplastic with thixotropy
- Dilatant
- Plastic with no yield value
Correct Answer: Pseudoplastic with thixotropy
Q12. The degree of flocculation (β) is defined as:
- The ratio of sediment volume of flocculated to deflocculated suspension
- The ratio of particle size after milling to before milling
- The viscosity of suspension at infinite shear
- The zeta potential multiplied by surface area
Correct Answer: The ratio of sediment volume of flocculated to deflocculated suspension
Q13. Which excipient functions primarily to wet hydrophobic particles in a suspension?
- Suspending agent
- Wetting agent (surfactant)
- Buffering agent
- Sweetening agent
Correct Answer: Wetting agent (surfactant)
Q14. Which factor does NOT significantly affect sedimentation rate according to Stoke’s law?
- Particle diameter
- Density difference
- Gravity
- Particle color
Correct Answer: Particle color
Q15. Which test assesses the ease with which a sediment can be redispersed after standing?
- Redispersibility test
- pH stability test
- Microbial limit test
- Assay by HPLC
Correct Answer: Redispersibility test
Q16. Which ionic additive is commonly used as a chelating agent to improve preservative effectiveness?
- EDTA (disodium EDTA)
- Sodium lauryl sulfate
- Calcium chloride
- Potassium sorbate
Correct Answer: EDTA (disodium EDTA)
Q17. What is the main disadvantage of very high viscosity in a suspension?
- Improved chemical stability
- Poor pourability and patient acceptability
- Enhanced microbial protection
- Reduced sedimentation rate without drawback
Correct Answer: Poor pourability and patient acceptability
Q18. Which of the following indicates a deflocculated suspension?
- Rapid settling with compact cake formation
- Rapid settling with loose easily redispersible sediment
- No settling at all
- Complete dissolution of particles
Correct Answer: Rapid settling with compact cake formation
Q19. Which analytical parameter helps determine particle size distribution in suspensions?
- Zeta potential measurement
- Laser diffraction or microscopy
- pH meter
- Viscosity at zero shear
Correct Answer: Laser diffraction or microscopy
Q20. Addition of electrolytes to a suspension primarily affects which stabilizing mechanism?
- Steric stabilization by polymers
- Electrostatic stabilization by changing double layer thickness
- Viscosity increase due to polymers
- Direct reduction of particle size
Correct Answer: Electrostatic stabilization by changing double layer thickness
Q21. Which surfactant classification is most suitable as a wetting agent for oral suspensions?
- Anionic surfactants only
- Nonionic surfactants (e.g., polysorbates)
- Cationic surfactants only
- No surfactants are suitable
Correct Answer: Nonionic surfactants (e.g., polysorbates)
Q22. Which phenomenon describes time-dependent shear thinning behavior useful in suspensions?
- Dilatancy
- Thixotropy
- Rheopexy
- Newtonian flow
Correct Answer: Thixotropy
Q23. In suspension formulation, what is the role of a flocculating agent?
- To increase drug solubility by chemical reaction
- To promote controlled aggregation forming loose flocs
- To sterilize the formulation
- To act as a sweetening agent
Correct Answer: To promote controlled aggregation forming loose flocs
Q24. Which container attribute is most important for light-sensitive suspensions?
- Opaque or amber glass/plastic to reduce light exposure
- Wide mouth for easier pouring
- Colored cap for branding
- Transparent glass to monitor sediment
Correct Answer: Opaque or amber glass/plastic to reduce light exposure
Q25. Which method is suitable for sterilizing heat-sensitive suspensions that require sterile product?
- Autoclaving the final suspension
- Sterile filtration of suspension containing particles larger than filter pore
- Preparing under aseptic conditions with sterile ingredients and containers
- Adding high concentration of alcohol for sterilization
Correct Answer: Preparing under aseptic conditions with sterile ingredients and containers
Q26. Which test would directly assess the electrostatic stabilization of particles?
- Determination of sedimentation volume
- Zeta potential measurement
- pH titration
- Viscosity profiling
Correct Answer: Zeta potential measurement
Q27. Which preservative may be less effective in presence of high levels of nonionic surfactants due to micelle interaction?
- Benzoic acid
- Benzalkonium chloride
- Phenoxyethanol
- Methylparaben
Correct Answer: Methylparaben
Q28. For topical suspensions, which property is especially important compared to oral suspensions?
- Taste masking
- Spreadability and skin feel
- Sweetness
- Oral bioavailability
Correct Answer: Spreadability and skin feel
Q29. Which manufacturing technique reduces particle size by high shear and cavitation forces?
- Hand trituration only
- High-pressure homogenization
- Simple stirring
- Freeze drying
Correct Answer: High-pressure homogenization
Q30. What is the primary reason to include buffers in suspension formulations?
- To control pH and maintain drug stability and preservative effectiveness
- To increase particle size
- To act as suspending agents
- To directly enhance viscosity
Correct Answer: To control pH and maintain drug stability and preservative effectiveness
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