Particle Coating Techniques MCQs With Answer

Particle Coating Techniques MCQs With Answer — Introduction

This quiz set focuses on particle coating techniques relevant to M.Pharm students studying Pharmaceutical Production Technology. It covers principles, equipment, formulation components, process parameters, common defects and quality-control tests involved in coating particles such as pellets, granules and beads. Questions probe deeper aspects like fluidized-bed and pan coating mechanisms, spray atomization, solvent choices, polymer selection for enteric or sustained-release coatings, and troubleshooting of coating failures. Use these MCQs to test and reinforce your understanding of the theoretical basis and practical considerations needed for developing robust coating processes and ensuring consistent product performance.

Q1. Which of the following best describes the Wurster (bottom-spray) fluidized bed coating process?

• A top-spray technique where coating is applied from above onto a static bed
• A bottom-spray technique where particles circulate through a draft tube and are coated in an ascending spray zone
• A pan coating variant using centrifugal force to coat tablets
• An immersion coating method in which particles are dipped into polymer solution

Correct Answer: A bottom-spray technique where particles circulate through a draft tube and are coated in an ascending spray zone

Q2. Which polymer is most commonly used as an enteric coating for delayed-release formulations?

• Hydroxypropyl methylcellulose (HPMC)
• Ethylcellulose
• Cellulose acetate phthalate (CAP)
• Polyvinylpyrrolidone (PVP)

Correct Answer: Cellulose acetate phthalate (CAP)

Q3. What is the primary role of a plasticizer in a film coating formulation?

• To increase the viscosity of the coating dispersion
• To improve film flexibility and reduce brittleness
• To act as the primary film-forming polymer
• To accelerate solvent evaporation during coating

Correct Answer: To improve film flexibility and reduce brittleness

Q4. Which coating defect is most likely caused by insufficient drying leading to tacky particles and agglomeration?

• Orange peel
• Peeling
• Sticking and agglomeration
• Cracking

Correct Answer: Sticking and agglomeration

Q5. In spray coating, reducing atomization pressure while keeping nozzle orifice constant typically results in what effect on droplet size?

• Smaller droplet size
• No change in droplet size
• Larger droplet size
• Immediate solvent evaporation preventing film formation

Correct Answer: Larger droplet size

Q6. Which of the following materials is commonly used for sustained-release coatings because it is water-insoluble but permeable?

• Hydroxypropyl methylcellulose (HPMC)
• Ethylcellulose
• Polyethylene glycol (PEG)
• Gellan gum

Correct Answer: Ethylcellulose

Q7. Which process parameter is most critical to avoid thermal degradation of a heat-sensitive active during aqueous spray coating?

• Agent of atomization (air vs. pressure)
• Inlet air temperature and drying capacity
• Nozzle diameter only
• pH of coating dispersion

Correct Answer: Inlet air temperature and drying capacity

Q8. What is “weight gain” in the context of particle coating?

• The percentage increase in mass of individual particles due to the applied coat
• The total mass of coating suspension sprayed per hour
• The increase in particle diameter in micrometers only
• The weight of solvent evaporated during coating

Correct Answer: The percentage increase in mass of individual particles due to the applied coat

Q9. Which analytical technique is most appropriate to visually confirm coating thickness and surface morphology of coated pellets?

• High-performance liquid chromatography (HPLC)
• Scanning electron microscopy (SEM)
• Fourier-transform infrared spectroscopy (FTIR)
• UV-Vis spectrophotometry

Correct Answer: Scanning electron microscopy (SEM)

Q10. A common cause of “orange peel” appearance in film-coated particles is:

• Excessive plasticizer concentration
• Poor atomization giving large droplets and insufficient coalescence
• Use of water-soluble polymers only
• Too low spray rate and over-drying

Correct Answer: Poor atomization giving large droplets and insufficient coalescence

Q11. During scale-up of a coating process from lab to production, which parameter must be matched to maintain similar droplet formation and coating behavior?

• Nozzle manufacturer only
• Spray droplet size distribution and air-to-solids ratio
• Just the inlet air temperature
• Colorant concentration in the coating

Correct Answer: Spray droplet size distribution and air-to-solids ratio

Q12. Which solvent system is preferred for most modern commercial film coatings due to safety and regulatory concerns?

• Chloroform-based organic systems
• Acetone-only systems
• Water-based aqueous polymer dispersions
• Pure methanol solutions

Correct Answer: Water-based aqueous polymer dispersions

Q13. Which coating polymer is ionic and commonly used for pH-dependent (enteric) release in the stomach and intestine?

• Ethylcellulose (non-ionic)
• Eudragit L (anionic methacrylic acid copolymer)
• Povidone (non-ionic)
• Polydimethylsiloxane

Correct Answer: Eudragit L (anionic methacrylic acid copolymer)

Q14. Which of the following strategies increases coating throughput without increasing spray rate per nozzle?

• Reducing bed agitation to minimize particle movement
• Using multiple spray guns/nozzles and optimizing air flow
• Lowering inlet air temperature drastically
• Increasing solvent content of the coating dispersion

Correct Answer: Using multiple spray guns/nozzles and optimizing air flow

Q15. If a film-coated pellet shows cracking after curing, the most likely cause is:

• Excessive plasticizer concentration
• Insufficient plasticizer or too rapid solvent evaporation during coating
• Use of a flexible polymer like HPMC
• Excessive weight gain (too thick a film)

Correct Answer: Insufficient plasticizer or too rapid solvent evaporation during coating

Q16. Which measurement is typically used for routine in-process control to estimate coating uniformity across a batch of pellets?

• Assay of API by HPLC on a single pellet only
• Average weight gain and coefficient of variation (CV) of individual particle weights
• Particle colorimetric test only
• Infrared spectroscopy on bulk powder without separation

Correct Answer: Average weight gain and coefficient of variation (CV) of individual particle weights

Q17. For immediate film coating aimed only at taste-masking and aesthetic appearance, which polymer choice is most appropriate?

• Cellulose acetate phthalate (enteric)
• Ethylcellulose (water-insoluble sustained-release)
• Hydroxypropyl methylcellulose (HPMC) aqueous solution
• Eudragit RS (sustained-release)

Correct Answer: Hydroxypropyl methylcellulose (HPMC) aqueous solution

Q18. Which coating defect indicates poor adhesion between the coat and the substrate and may lead to coating coming off during handling?

• Twinning
• Peeling (delamination)
• Orange peel
• Polishing

Correct Answer: Peeling (delamination)

Q19. What is the effect of increasing solids content of the coating dispersion while keeping spray rate constant?

• Longer drying time required and lower final film thickness for same weight gain
• Higher mass of polymer deposited per unit volume sprayed, potentially reducing spray time but increasing risk of poor atomization
• No change in deposition efficiency
• Decrease in viscosity always leading to better coating quality

Correct Answer: Higher mass of polymer deposited per unit volume sprayed, potentially reducing spray time but increasing risk of poor atomization

Q20. Which test best correlates with the functional performance of an enteric-coated pellet batch?

• Friability testing in water
• Disintegration/dissolution testing in sequential pH media
• Bulk density measurement at room temperature
• Particle size analysis by sieve only

Correct Answer: Disintegration/dissolution testing in sequential pH media

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