Microencapsulation is a key technology in modern pharmaceuticals for improving drug stability, controlled release, targeted delivery, taste masking, and enhanced bioavailability. B. Pharm students should understand common encapsulation techniques such as spray drying, coacervation, solvent evaporation, liposomal and polymeric microsphere methods, and materials like PLGA, alginate and chitosan. Knowledge of characterization (particle size, encapsulation efficiency, release kinetics), release mechanisms (diffusion, erosion, swelling) and formulation challenges (sterilization, scale-up, stability) is essential for designing effective dosage forms. This introduction prepares you for application-focused questions linking theory to practice. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. What is the primary pharmaceutical advantage of microencapsulation?
- Reducing manufacturing costs
- Enhancing drug stability and enabling controlled release
- Improving tablet hardness only
- Replacing active pharmaceutical ingredients
Correct Answer: Enhancing drug stability and enabling controlled release
Q2. Which encapsulation technique commonly uses an oil-in-water emulsion followed by solvent evaporation to form polymeric microspheres?
- Spray drying
- Coacervation
- Solvent evaporation (emulsion solvent evaporation)
- Freeze-drying
Correct Answer: Solvent evaporation (emulsion solvent evaporation)
Q3. Which polymer is widely used for biodegradable, controlled-release microspheres in parenteral formulations?
- Polyvinylpyrrolidone (PVP)
- Poly(lactic-co-glycolic acid) (PLGA)
- Sodium chloride
- Polyethylene glycol 400 (PEG 400)
Correct Answer: Poly(lactic-co-glycolic acid) (PLGA)
Q4. Encapsulation efficiency is best defined as which expression?
- (Amount of polymer used / Total formulation weight) × 100
- (Amount of drug released / Amount of drug encapsulated) × 100
- (Amount of drug encapsulated / Initial amount of drug used) × 100
- (Particle size / Encapsulation time) × 100
Correct Answer: (Amount of drug encapsulated / Initial amount of drug used) × 100
Q5. Which microencapsulation method is most suitable for heat-sensitive proteins and vaccines?
- Conventional spray drying at high inlet temperature
- Solvent extraction with high shear
- Freeze-drying (lyophilization) or low-temperature processes
- Direct compression
Correct Answer: Freeze-drying (lyophilization) or low-temperature processes
Q6. Which mechanism commonly explains drug release from a non-erodible polymer matrix?
- Osmotic bursting only
- Diffusion through the polymer matrix
- Immediate dissolution without barrier
- Covalent bond cleavage
Correct Answer: Diffusion through the polymer matrix
Q7. The Higuchi model describes release kinetics where cumulative drug release is proportional to which mathematical function of time?
- Time (t)
- Square root of time (t^1/2)
- Logarithm of time (log t)
- Exponential of time (e^t)
Correct Answer: Square root of time (t^1/2)
Q8. Which microencapsulation application is especially useful for masking bitter taste in oral formulations?
- Increasing hygroscopicity
- Taste masking by coating drug particles with polymers
- Accelerating dissolution in the oral cavity
- Promoting immediate gastric degradation
Correct Answer: Taste masking by coating drug particles with polymers
Q9. Which natural polymer is frequently used for ionic gelation-based microencapsulation and is mucoadhesive?
- Polystyrene
- Chitosan
- Polypropylene
- Sodium lauryl sulfate
Correct Answer: Chitosan
Q10. Interfacial polymerization primarily produces which type of microcapsule structure?
- Matrix-type particles where drug is uniformly dispersed
- Core-shell capsules with a distinct shell surrounding the core
- Bulk gels without defined interface
- Single-molecule complexes
Correct Answer: Core-shell capsules with a distinct shell surrounding the core
Q11. Which factor typically increases the initial burst release from microspheres?
- Decreasing surface drug load
- Strong crosslinking of the polymer
- Drug adsorbed on the particle surface or shallowly embedded
- Using high molecular weight polymer with low porosity
Correct Answer: Drug adsorbed on the particle surface or shallowly embedded
Q12. Which characterization technique is essential for determining particle size distribution of microparticles?
- X‑ray diffraction (XRD)
- Laser diffraction or dynamic light scattering
- Fourier-transform infrared spectroscopy (FTIR)
- pH titration
Correct Answer: Laser diffraction or dynamic light scattering
Q13. Microencapsulation of antibiotics can provide which therapeutic benefit?
- Increased antibiotic toxicity only
- Targeted delivery to infection sites and sustained therapeutic levels
- Elimination of the need for dosing
- Immediate systemic elimination
Correct Answer: Targeted delivery to infection sites and sustained therapeutic levels
Q14. Which encapsulation method forms particles by spraying a polymer solution into a hot gas stream?
- Spray drying
- Coacervation-phase separation
- Emulsion polymerization
- Supercritical fluid drying
Correct Answer: Spray drying
Q15. For encapsulating highly water-soluble drugs with high encapsulation efficiency, which strategy is most appropriate?
- Use oil-in-water emulsion without adjustments
- Use double emulsion (w/o/w) or ion-pairing to retain drug in polymer phase
- Always use spray drying at high temperature
- Exclude polymer completely
Correct Answer: Use double emulsion (w/o/w) or ion-pairing to retain drug in polymer phase
Q16. Which release mechanism involves polymer chain cleavage and mass loss of the carrier?
- Diffusion-controlled release
- Erosion or biodegradation-controlled release
- Osmotic equilibrium only
- Surface adsorption
Correct Answer: Erosion or biodegradation-controlled release
Q17. Which property of microspheres most directly affects injectability and syringeability for parenteral suspensions?
- Color
- Particle size and size distribution
- Smell
- Encapsulation temperature
Correct Answer: Particle size and size distribution
Q18. In developing oral multiparticulate systems, microencapsulated pellets are preferred because they:
- Always cause gastric irritation
- Allow flexible dosing, uniform GI transit and reduced variability
- Cannot be filled into capsules
- Require single-unit tablet compression only
Correct Answer: Allow flexible dosing, uniform GI transit and reduced variability
Q19. Which analytical test is most appropriate to assess chemical stability of an encapsulated drug during storage?
- Mechanical hardness test
- Assay by validated chromatographic method (e.g., HPLC)
- Viscosity of the polymer solution only
- Colorimeter reading only
Correct Answer: Assay by validated chromatographic method (e.g., HPLC)
Q20. What is a common advantage of nanoencapsulation versus microencapsulation for poorly soluble drugs?
- Reduced surface area and lower dissolution rate
- Increased surface area leading to improved dissolution and bioavailability
- Elimination of need for API characterization
- Guaranteed oral absorption regardless of chemistry
Correct Answer: Increased surface area leading to improved dissolution and bioavailability
Q21. Which microencapsulation application is particularly important for probiotic formulations?
- Accelerating probiotic metabolism before administration
- Protecting live organisms from gastric acidity and bile salts
- Converting probiotics to synthetic antibiotics
- Increasing probiotic sensitivity to heat
Correct Answer: Protecting live organisms from gastric acidity and bile salts
Q22. Which factor tends to slow drug release from a biodegradable polymer microsphere?
- Lower polymer molecular weight
- Higher crosslink density or higher polymer molecular weight
- Higher porosity and surface area
- Smaller particle size
Correct Answer: Higher crosslink density or higher polymer molecular weight
Q23. Which in vitro test is used to predict in vivo drug release behavior from microcapsules?
- Intrinsic dissolution under sink conditions and similarity to physiological media
- Heat shrinkage test only
- Color matching to reference standard
- Tablet friability test
Correct Answer: Intrinsic dissolution under sink conditions and similarity to physiological media
Q24. What is a major scale-up challenge when moving from lab-scale microencapsulation to commercial production?
- Reducing API potency
- Maintaining consistent particle size distribution and solvent removal reproducibility
- Increasing variability between batches intentionally
- Removing need for quality control tests
Correct Answer: Maintaining consistent particle size distribution and solvent removal reproducibility
Q25. Which statement about liposomes as an encapsulation system is correct?
- Liposomes are rigid non-biocompatible polymers
- Liposomes are vesicles composed of phospholipid bilayers capable of encapsulating hydrophilic and lipophilic drugs
- Liposomes cannot be used for targeted delivery
- Liposomes are formed only by spray drying
Correct Answer: Liposomes are vesicles composed of phospholipid bilayers capable of encapsulating hydrophilic and lipophilic drugs
Q26. Which release kinetic model is typically associated with erosion-controlled release from biodegradable microspheres?
- Zero-order or near zero-order release during polymer erosion-controlled phase
- Higuchi square-root-only model always
- Instantaneous release at t=0 only
- Logarithmic decay without relation to erosion
Correct Answer: Zero-order or near zero-order release during polymer erosion-controlled phase
Q27. To improve encapsulation of a hydrophilic peptide in PLGA microspheres, formulators often:
- Skip using any stabilizer
- Use stabilizers (e.g., sugars), optimize double emulsion and control solvent removal
- Use only water as solvent without polymer
- Heat the peptide to increase solubility
Correct Answer: Use stabilizers (e.g., sugars), optimize double emulsion and control solvent removal
Q28. Which sterilization method is commonly problematic for protein-loaded polymeric microspheres due to radiation-induced degradation?
- Aseptic manufacturing processes
- Gamma irradiation
- Sterile filtration of the finished microparticles
- Ethylene oxide at low temperature with validated removal
Correct Answer: Gamma irradiation
Q29. Which statement best describes multiparticulate microencapsulated dosage forms compared to single-unit systems?
- They have higher risk of dose dumping under all conditions
- They provide more predictable GI distribution, reduced local irritation and flexible dosing
- They cannot achieve controlled release profiles
- They are always more difficult to manufacture with no patient benefits
Correct Answer: They provide more predictable GI distribution, reduced local irritation and flexible dosing
Q30. Which formulation approach can produce pH-sensitive release using microencapsulation for targeted intestinal delivery?
- Using enteric polymers or pH-responsive coatings that dissolve at intestinal pH
- Using polymers that dissolve only in acidic gastric pH
- Using plain sugar coating without polymer
- Eliminating all coatings to ensure immediate gastric release
Correct Answer: Using enteric polymers or pH-responsive coatings that dissolve at intestinal pH
I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.
Mail- Sachin@pharmacyfreak.com