Q.1 What is the primary purpose of microencapsulation in drug delivery systems?
To increase the drug's solubility
To protect the drug from degradation
To enhance the drug's color
To reduce the manufacturing cost
Explanation - Microencapsulation surrounds the active drug with a protective coating, shielding it from environmental factors such as pH, enzymes, and light.
Correct answer is: To protect the drug from degradation
Q.2 Which technique is most commonly used for preparing polymeric microparticles?
Spray drying
Electrospinning
Melt extrusion
Supercritical fluid extraction
Explanation - Spray drying rapidly converts a liquid feed containing polymer and drug into dry microparticles by atomizing the liquid into a hot drying chamber.
Correct answer is: Spray drying
Q.3 In the context of microencapsulation, what does the term 'burst release' refer to?
A rapid initial release of drug
A delayed release after 24 h
Complete lack of drug release
Steady, constant release over weeks
Explanation - Burst release is the phenomenon where a large fraction of the encapsulated drug is released immediately upon administration, often due to surface‑adsorbed drug.
Correct answer is: A rapid initial release of drug
Q.4 Which polymer is widely used for biodegradable microparticles in drug delivery?
Polyvinyl chloride (PVC)
Polylactic‑co‑glycolic acid (PLGA)
Polyethylene terephthalate (PET)
Polystyrene (PS)
Explanation - PLGA degrades into lactic and glycolic acids, which are naturally metabolized, making it suitable for controlled drug release.
Correct answer is: Polylactic‑co‑glycolic acid (PLGA)
Q.5 Which parameter most directly influences the size of microparticles produced by the emulsion‑solvent evaporation method?
Stirring speed
Polymer molecular weight
Drug solubility in water
Ambient temperature
Explanation - Higher stirring speeds create smaller droplets during emulsification, leading to smaller final microparticles after solvent evaporation.
Correct answer is: Stirring speed
Q.6 What is the main advantage of using a double‑emulsion (W/O/W) method for protein encapsulation?
It eliminates the need for organic solvents
It provides higher encapsulation efficiency for hydrophilic molecules
It produces the smallest possible particles
It allows direct solid‑state drug loading
Explanation - The double‑emulsion technique traps aqueous protein solutions inside an internal aqueous phase, improving encapsulation of hydrophilic drugs.
Correct answer is: It provides higher encapsulation efficiency for hydrophilic molecules
Q.7 Which analytical technique is most suitable for determining the surface morphology of microparticles?
Differential scanning calorimetry (DSC)
Scanning electron microscopy (SEM)
High‑performance liquid chromatography (HPLC)
Fourier transform infrared spectroscopy (FTIR)
Explanation - SEM provides high‑resolution images of the particle surface, revealing shape, porosity, and texture.
Correct answer is: Scanning electron microscopy (SEM)
Q.8 In microencapsulation, the term 'lag time' refers to:
The time needed to form a stable emulsion
The period before any drug is released from the carrier
The delay between drug administration and therapeutic effect
The duration of the manufacturing process
Explanation - Lag time is the initial interval where the encapsulated drug remains unreleased, often due to the diffusion barrier of the coating.
Correct answer is: The period before any drug is released from the carrier
Q.9 Which factor most strongly affects the degradation rate of PLGA microparticles?
The ratio of lactic to glycolic acid
The color of the polymer
The type of solvent used in preparation
The presence of surfactants during emulsification
Explanation - Higher glycolic content accelerates hydrolysis, while higher lactic content slows degradation due to increased hydrophobicity.
Correct answer is: The ratio of lactic to glycolic acid
Q.10 Which of the following is a common surfactant used in the preparation of oil‑in‑water emulsions for microparticle formation?
Sodium dodecyl sulfate (SDS)
Polyvinyl alcohol (PVA)
Polytetrafluoroethylene (PTFE)
Silicone oil
Explanation - PVA stabilizes droplets during emulsification and is easily removed after particle formation.
Correct answer is: Polyvinyl alcohol (PVA)
Q.11 What is the primary reason for coating microparticles with a mucoadhesive polymer like chitosan?
To increase particle size
To enhance drug solubility
To promote adhesion to mucosal surfaces
To make particles magnetic
Explanation - Chitosan carries a positive charge that interacts with the negatively charged mucosal layer, prolonging residence time.
Correct answer is: To promote adhesion to mucosal surfaces
Q.12 Which release kinetic model describes drug release from a matrix where diffusion is the rate‑controlling step?
Zero‑order kinetics
First‑order kinetics
Higuchi model
Korsmeyer‑Peppas model
Explanation - The Higuchi equation predicts release proportional to the square root of time, typical for diffusion‑controlled systems.
Correct answer is: Higuchi model
Q.13 In microparticle drug delivery, what is meant by 'encapsulation efficiency'?
The percentage of drug that remains stable after storage
The ratio of the drug mass inside particles to the total drug initially used
The speed at which the drug is released
The degree of particle size uniformity
Explanation - Encapsulation efficiency quantifies how much of the initial drug load ends up encapsulated within the particles.
Correct answer is: The ratio of the drug mass inside particles to the total drug initially used
Q.14 Which method can be used to produce porous microparticles for rapid drug release?
Coacervation
Lyophilization (freeze‑drying)
Solvent evaporation without porogen
Hot melt extrusion
Explanation - Freeze‑drying removes solvent from frozen droplets, creating a highly porous structure that facilitates quick dissolution.
Correct answer is: Lyophilization (freeze‑drying)
Q.15 What is the main disadvantage of using organic solvents like dichloromethane in microencapsulation?
They increase particle size
They may leave toxic residues in the final product
They prevent drug loading
They reduce encapsulation efficiency
Explanation - Residual organic solvents can be harmful and require thorough removal to meet safety standards.
Correct answer is: They may leave toxic residues in the final product
Q.16 Which of the following drugs would most benefit from encapsulation in a pH‑sensitive microparticle designed for colon targeting?
A drug that is stable in acidic stomach pH
A drug that is degraded by gastric acid
A drug that requires rapid absorption in the duodenum
A drug that is hydrophobic and poorly soluble
Explanation - pH‑sensitive systems protect the drug in the stomach and release it when reaching the higher pH of the colon.
Correct answer is: A drug that is degraded by gastric acid
Q.17 What is the purpose of adding a plasticizer such as glycerol to a polymeric microparticle formulation?
To increase the polymer's Tg
To improve flexibility and reduce brittleness of the particles
To increase the particle's density
To act as a surfactant
Explanation - Plasticizers intercalate between polymer chains, lowering Tg and making the matrix more flexible.
Correct answer is: To improve flexibility and reduce brittleness of the particles
Q.18 Which device is commonly used to generate uniform droplets for microencapsulation via the spray‑drying method?
High‑shear homogenizer
Ultrasonic nozzle
Büchi Mini Spray Dryer (atomizer)
Rotary evaporator
Explanation - The atomizer creates fine droplets that dry rapidly, forming uniform microparticles.
Correct answer is: Büchi Mini Spray Dryer (atomizer)
Q.19 In a drug‑loaded microparticle, the term 'core‑shell' refers to:
A particle with a drug‑rich core surrounded by a polymeric shell
A particle composed entirely of drug
A particle where the drug is adsorbed on the surface only
A particle with multiple layers of different polymers
Explanation - Core‑shell structures allow separate control of core drug concentration and shell barrier properties.
Correct answer is: A particle with a drug‑rich core surrounded by a polymeric shell
Q.20 Which of the following is a key advantage of using microfluidic devices for microparticle production?
Very high production rates
Precise control over particle size distribution
No need for polymers
Ability to produce macroscopic tablets
Explanation - Microfluidics enable monodisperse droplet formation, resulting in uniform particle sizes.
Correct answer is: Precise control over particle size distribution
Q.21 The term 'hydrophobic drug loading' in polymeric microparticles is most closely associated with:
Using water‑soluble polymers
Encapsulating drugs that are soluble in organic solvents
Increasing the surfactant concentration
Reducing the particle size to nanometer scale
Explanation - Hydrophobic drugs dissolve in the organic phase used during emulsification, leading to higher loading efficiencies.
Correct answer is: Encapsulating drugs that are soluble in organic solvents
Q.22 Which characterization technique can quantify the amount of drug released from microparticles over time?
X‑ray diffraction (XRD)
Dynamic light scattering (DLS)
UV‑Visible spectrophotometry
Thermogravimetric analysis (TGA)
Explanation - UV‑Vis measures drug concentration in the release medium at different time points, providing a release profile.
Correct answer is: UV‑Visible spectrophotometry
Q.23 What is the role of cross‑linking agents such as glutaraldehyde in the preparation of gelatin microparticles?
To increase particle size
To stabilize the particle matrix and reduce dissolution rate
To act as a surfactant
To change the drug's chemical structure
Explanation - Cross‑linking forms covalent bonds between polymer chains, making the matrix more resistant to premature degradation.
Correct answer is: To stabilize the particle matrix and reduce dissolution rate
Q.24 Which of the following is a disadvantage of using the coacervation phase‑separation method?
Requires high temperatures
Limited to hydrophilic drugs
Often yields low encapsulation efficiency for hydrophobic drugs
Produces particles with a broad size distribution
Explanation - Coacervation can result in variable droplet formation, leading to heterogenous particle sizes.
Correct answer is: Produces particles with a broad size distribution
Q.25 In microparticle formulations, the term 'zeta potential' is used to describe:
Particle surface charge influencing stability
The thermal stability of the polymer
The drug loading capacity
The rate of drug release
Explanation - Zeta potential indicates electrostatic repulsion between particles; higher magnitude values suggest better suspension stability.
Correct answer is: Particle surface charge influencing stability
Q.26 Which of the following polymers is naturally derived and often used for mucoadhesive microparticles?
Polyethylene glycol (PEG)
Chitosan
Polymethyl methacrylate (PMMA)
Polyvinyl chloride (PVC)
Explanation - Chitosan, derived from chitin, exhibits mucoadhesive properties due to its cationic nature.
Correct answer is: Chitosan
Q.27 Which factor is most critical for achieving sustained drug release over weeks from PLGA microparticles?
Particle color
Polymer molecular weight and lactide:glycolide ratio
Presence of surfactant
Ambient humidity during storage
Explanation - Higher molecular weight and higher lactide content slow degradation, extending release duration.
Correct answer is: Polymer molecular weight and lactide:glycolide ratio
Q.28 What is the main purpose of lyophilizing a drug‑loaded microsphere suspension?
To increase the particle size
To convert the suspension into a dry powder for improved stability
To dissolve the polymer matrix
To embed magnetic nanoparticles
Explanation - Lyophilization removes water without heating, preserving drug activity and particle integrity.
Correct answer is: To convert the suspension into a dry powder for improved stability
Q.29 Which release mechanism is predominant for drug molecules that are covalently bound to the polymer matrix?
Diffusion
Polymer erosion
Chemical degradation of the drug‑polymer bond
Swelling
Explanation - Release occurs when the covalent linkage is cleaved, often via hydrolysis or enzymatic action.
Correct answer is: Chemical degradation of the drug‑polymer bond
Q.30 When designing a microparticle for intranasal delivery, which characteristic is most important?
Particle size below 10 µm
High density
Hydrophobic surface
Metallic core
Explanation - Particles smaller than ~10 µm can penetrate the nasal mucosa and reach the olfactory region effectively.
Correct answer is: Particle size below 10 µm
Q.31 What does the term 'bioavailability' refer to in the context of drug delivery systems?
The amount of drug that reaches systemic circulation unchanged
The particle size distribution of the formulation
The color intensity of the drug solution
The rate at which a drug degrades in vitro
Explanation - Bioavailability measures the fraction of an administered dose that becomes available at the site of action.
Correct answer is: The amount of drug that reaches systemic circulation unchanged
Q.32 Which of the following is a common method to assess the mechanical strength of a microparticle pellet?
Hardness test using a tablet press
Compression test with a texture analyzer
Particle size analysis by laser diffraction
UV‑Vis spectroscopy
Explanation - A texture analyzer can apply controlled force to a single particle and record deformation or fracture.
Correct answer is: Compression test with a texture analyzer
Q.33 In microparticulate drug delivery, the term 'nanoprecipitation' typically refers to:
Formation of nanoparticles from a supersaturated polymer solution
Precipitation of large crystals from a solution
Drying of microparticles in a vacuum oven
Sintering of polymer particles at high temperature
Explanation - Nanoprecipitation involves rapid solvent displacement, leading to nucleation of nano‑sized particles.
Correct answer is: Formation of nanoparticles from a supersaturated polymer solution
Q.34 Which of the following is the most suitable method to achieve targeted delivery of anticancer drugs to tumor tissue using microparticles?
Encapsulation in pH‑responsive particles that release at acidic tumor pH
Coating particles with a sweet flavor
Using particles larger than 500 µm
Adding iron oxide to make particles magnetic
Explanation - Tumor microenvironments are often acidic; pH‑responsive carriers release the drug preferentially at the tumor site.
Correct answer is: Encapsulation in pH‑responsive particles that release at acidic tumor pH
Q.35 Which polymer property determines whether a microparticle will swell significantly in aqueous media?
Hydrophobicity
Molecular weight
Hydrophilicity
Crystallinity
Explanation - Hydrophilic polymers absorb water, leading to swelling; hydrophobic polymers resist water uptake.
Correct answer is: Hydrophilicity
Q.36 The term 'burst effect' in drug release can be minimized by:
Increasing surface‑adsorbed drug amount
Adding a coating layer that reduces surface drug
Using a highly porous matrix
Decreasing polymer molecular weight
Explanation - A secondary coating can seal surface‑adsorbed drug, lowering the initial rapid release.
Correct answer is: Adding a coating layer that reduces surface drug
Q.37 Which of the following is a disadvantage of using inorganic carriers such as silica for drug encapsulation?
They are biodegradable
They have limited surface functionalization
They can cause irritation if not properly sized
They are too soft for handling
Explanation - Inorganic particles may be cytotoxic or cause inflammation if they are too large or sharp.
Correct answer is: They can cause irritation if not properly sized
Q.38 Which analytical method can be used to confirm the chemical integrity of a drug after encapsulation?
Fourier transform infrared spectroscopy (FTIR)
Scanning electron microscopy (SEM)
Dynamic light scattering (DLS)
Thermal gravimetric analysis (TGA)
Explanation - FTIR detects functional groups and can reveal chemical changes or degradation of the drug.
Correct answer is: Fourier transform infrared spectroscopy (FTIR)
Q.39 When formulating microparticles for pulmonary delivery, which aerodynamic parameter is most critical?
Particle density
Aerodynamic diameter (MMAD)
Surface charge
Color
Explanation - The Mass Median Aerodynamic Diameter determines deposition location in the respiratory tract.
Correct answer is: Aerodynamic diameter (MMAD)
Q.40 Which of the following statements about 'controlled release' is correct?
It always requires a polymer matrix
It aims to maintain drug concentrations within the therapeutic window over a defined period
It eliminates the need for any drug metabolism
It is only achievable with nanometer‑sized particles
Explanation - Controlled release systems are designed to provide a predictable drug release rate to achieve sustained therapeutic levels.
Correct answer is: It aims to maintain drug concentrations within the therapeutic window over a defined period
Q.41 In a W/O/W double‑emulsion system, what is the purpose of the inner aqueous phase?
To dissolve the polymer
To encapsulate hydrophilic drugs
To act as a surfactant
To increase viscosity of the external phase
Explanation - The inner water phase traps hydrophilic molecules, allowing them to be enclosed within the polymeric shell formed by the oil phase.
Correct answer is: To encapsulate hydrophilic drugs
Q.42 Which parameter is directly measured by Dynamic Light Scattering (DLS) for microparticle suspensions?
Particle shape
Particle size distribution (hydrodynamic diameter)
Surface charge
Chemical composition
Explanation - DLS analyzes fluctuations in scattered light to calculate the hydrodynamic diameter of particles in suspension.
Correct answer is: Particle size distribution (hydrodynamic diameter)
Q.43 A microparticle formulation exhibits a 'zero‑order' release profile. Which statement best describes this profile?
The release rate decreases exponentially over time
The drug is released at a constant rate regardless of concentration
The release rate is proportional to the remaining drug amount
The drug is released only after a lag time
Explanation - Zero‑order kinetics means a constant amount of drug is released per unit time, leading to a linear cumulative release curve.
Correct answer is: The drug is released at a constant rate regardless of concentration
Q.44 Which of the following is a key advantage of using biodegradable polymers for microparticle drug carriers?
They can be stored indefinitely without degradation
They eliminate the need for surgical removal after drug release
They provide unlimited drug loading capacity
They are always cheaper than non‑degradable polymers
Explanation - Biodegradable carriers break down into biocompatible by‑products that are safely eliminated from the body.
Correct answer is: They eliminate the need for surgical removal after drug release
Q.45 In microencapsulation, which factor primarily controls the rate of drug diffusion through the polymer matrix?
Polymer crystallinity
Particle color
Surfactant type
Ambient humidity
Explanation - Highly crystalline polymers have tighter packing, reducing free volume and slowing drug diffusion.
Correct answer is: Polymer crystallinity
Q.46 Which method can be employed to produce hollow (core‑free) polymeric microspheres?
Single emulsion (O/W) technique
Coaxial electrospraying
Solvent evaporation with a porogen
Freeze‑drying
Explanation - Coaxial electrospraying creates a core‑shell jet where the core solvent can be removed, leaving a hollow capsule.
Correct answer is: Coaxial electrospraying
Q.47 A drug-loaded microparticle exhibits a rapid initial release followed by a slower phase. This release pattern is best described as:
Biphasic release
Zero‑order release
First‑order release
Sustained release
Explanation - The biphasic pattern consists of an initial burst (fast) phase and a subsequent slower, controlled release phase.
Correct answer is: Biphasic release
Q.48 Which of the following solvents is most frequently used in the oil phase for the O/W emulsion method with PLGA?
Water
Acetone
Dichloromethane (DCM)
Ethanol
Explanation - DCM readily dissolves PLGA and evaporates quickly, facilitating particle solidification.
Correct answer is: Dichloromethane (DCM)
Q.49 In the context of microparticle drug delivery, the term 'hydrogel' refers to:
A dry polymer powder
A cross‑linked polymer network that swells in water
A metallic nanoparticle
A crystalline drug form
Explanation - Hydrogels absorb large amounts of water while maintaining structural integrity, useful for controlled drug release.
Correct answer is: A cross‑linked polymer network that swells in water
Q.50 Which factor most influences the mucoadhesive strength of chitosan‑based microparticles?
Degree of deacetylation of chitosan
Particle size above 100 µm
Use of a non‑ionic surfactant
Incorporation of metallic salts
Explanation - Higher deacetylation increases the number of free amino groups, enhancing electrostatic interactions with mucin.
Correct answer is: Degree of deacetylation of chitosan
Q.51 What is the main advantage of using a 'spray‑freeze drying' technique over conventional spray drying for heat‑sensitive drugs?
It produces larger particles
It eliminates the need for solvents
It involves rapid freezing, minimizing thermal exposure
It requires no equipment
Explanation - Spray‑freeze drying instantly freezes droplets, protecting thermolabile drugs from high temperatures.
Correct answer is: It involves rapid freezing, minimizing thermal exposure
Q.52 In a drug‑loaded microsphere, what is the effect of increasing the polymer to drug ratio?
Decreases encapsulation efficiency
Increases burst release
Reduces overall drug loading but may prolong release duration
Eliminates the need for surfactants
Explanation - More polymer relative to drug lowers the weight fraction of drug, yet the thicker matrix can extend the release period.
Correct answer is: Reduces overall drug loading but may prolong release duration
Q.53 Which of the following is a commonly used technique for sterility assurance of microparticle drug formulations?
Autoclaving at 121 °C
Gamma irradiation
Filtration through 0.45 µm membrane
Dry heating at 50 °C
Explanation - Gamma irradiation can sterilize powders without raising temperature, preserving drug and polymer integrity.
Correct answer is: Gamma irradiation
Q.54 When measuring the drug release from microparticles in vitro, why is sink conditions important?
To ensure the drug does not precipitate in the medium
To keep the temperature constant
To maintain pH stability
To prevent microbial growth
Explanation - Sink conditions maintain drug concentration well below its saturation solubility, allowing the release rate to be governed solely by the formulation.
Correct answer is: To ensure the drug does not precipitate in the medium
Q.55 Which polymer would be most suitable for formulating a microparticle intended for oral delivery with a rapid release in the stomach?
Eudragit® L100 (pH‑dependent, dissolves at pH > 6)
Polycaprolactone (PCL)
Chitosan (soluble in acidic pH)
Polyethylene glycol (PEG) of high molecular weight
Explanation - Chitosan dissolves in acidic environments like the stomach, facilitating rapid drug release.
Correct answer is: Chitosan (soluble in acidic pH)
Q.56 The term 'microparticulate' most accurately describes:
Particles with diameter between 1 mm and 10 mm
Particles with diameter ranging from 1 µm to 1000 µm
Nanoparticles smaller than 100 nm
Bulk crystals larger than 10 mm
Explanation - Microparticulates are defined as particles in the micrometer size range, typically 1–1000 µm.
Correct answer is: Particles with diameter ranging from 1 µm to 1000 µm
Q.57 Which of the following statements about the 'emulsion–solvent diffusion' method is true?
It requires high temperatures to evaporate the solvent
It uses a water‑in‑oil (W/O) primary emulsion followed by solvent diffusion into an external aqueous phase
It produces only nanometer‑sized particles
It does not require any surfactants
Explanation - The method forms a primary W/O emulsion; solvent diffuses out into the outer water phase, precipitating polymer particles.
Correct answer is: It uses a water‑in‑oil (W/O) primary emulsion followed by solvent diffusion into an external aqueous phase
Q.58 Which type of microparticle would be most appropriate for delivering a vaccine antigen that requires uptake by antigen‑presenting cells?
Large (>500 µm) inert beads
Microparticles made of biodegradable polymers with a size of 1–5 µm
Hydrophobic polymeric particles >50 µm
Metallic particles with a smooth surface
Explanation - Particles in this size range are efficiently phagocytosed by dendritic cells and macrophages, enhancing antigen presentation.
Correct answer is: Microparticles made of biodegradable polymers with a size of 1–5 µm
Q.59 Which analytical method can determine the crystallinity of a drug inside microparticles?
X‑ray diffraction (XRD)
Differential scanning calorimetry (DSC)
UV‑Vis spectroscopy
Zeta potential measurement
Explanation - XRD provides diffraction patterns that reveal crystalline versus amorphous phases.
Correct answer is: X‑ray diffraction (XRD)
Q.60 In the context of drug‑loaded microparticles, what does the term 'hydrophobic interaction' refer to?
Electrostatic attraction between charged groups
Van der Waals forces between non‑polar segments of drug and polymer
Hydrogen bonding with water molecules
Covalent bonding between drug and polymer
Explanation - Hydrophobic interactions arise from the tendency of non‑polar molecules to associate, influencing drug loading and release.
Correct answer is: Van der Waals forces between non‑polar segments of drug and polymer
Q.61 Which factor most directly influences the zeta potential of polymeric microparticles?
Particle size
Surface functional groups (e.g., carboxyl, amine)
Polymer molecular weight
Drug solubility
Explanation - Ionizable functional groups on the particle surface determine the net surface charge, reflected in the zeta potential.
Correct answer is: Surface functional groups (e.g., carboxyl, amine)
Q.62 A microparticle formulation shows a lag time of 4 h before any drug is released. Which design strategy could be used to reduce this lag time?
Increase polymer cross‑linking density
Decrease polymer molecular weight
Add a thicker coating layer
Increase particle size
Explanation - Lower molecular weight polymers degrade faster, reducing the diffusion barrier and shortening lag time.
Correct answer is: Decrease polymer molecular weight
Q.63 Which of the following is a typical use of microparticulate systems in the field of electrical engineering?
Fabricating printed circuit boards
Providing dielectric materials with tunable permittivity
Creating high‑strength structural composites
Designing optical lenses
Explanation - Embedding microparticles with specific dielectric properties can adjust the overall permittivity of composite materials used in EE applications.
Correct answer is: Providing dielectric materials with tunable permittivity
Q.64 Which polymer is commonly used to create pH‑responsive microparticles that swell at intestinal pH (≈7.4)?
Eudragit® S100 (pH > 7)
Polyvinyl alcohol (PVA)
Polystyrene (PS)
Cellulose acetate
Explanation - Eudragit S100 dissolves at pH > 7, making it suitable for colon‑targeted drug delivery.
Correct answer is: Eudragit® S100 (pH > 7)
Q.65 In the formulation of microparticles for ocular drug delivery, which property is most critical?
Particle density
Particle size less than 10 µm to avoid irritation
High surface roughness
Magnetic susceptibility
Explanation - Small particles minimize discomfort and can penetrate the corneal epithelium more effectively.
Correct answer is: Particle size less than 10 µm to avoid irritation
Q.66 Which of the following is a major limitation when using PLGA microparticles for the delivery of proteins?
Rapid polymer degradation
Potential for protein denaturation during organic solvent exposure
Inability to achieve high drug loading
Excessive particle swelling
Explanation - Proteins can unfold or lose activity when exposed to organic solvents used in PLGA particle preparation.
Correct answer is: Potential for protein denaturation during organic solvent exposure
Q.67 Which technique can be employed to achieve surface modification of microparticles with targeting ligands?
Physical adsorption
Covalent coupling via carbodiimide chemistry
Heat treatment at 200 °C
Grinding with a mortar and pestle
Explanation - Carbodiimide agents activate carboxyl groups for stable amide bond formation with amine‑containing ligands.
Correct answer is: Covalent coupling via carbodiimide chemistry
Q.68 What is the most common reason for particle aggregation during storage of microparticle suspensions?
High zeta potential magnitude
Low temperature
Insufficient surfactant or stabilizer
Excessive light exposure
Explanation - Without enough stabilizer, van der Waals attractions dominate, leading to aggregation.
Correct answer is: Insufficient surfactant or stabilizer
Q.69 Which of the following describes a 'bioadhesive' microparticle?
A particle that adheres to biological tissues, prolonging residence time
A particle that is magnetic
A particle that dissolves instantly upon contact with water
A particle that changes color in the presence of enzymes
Explanation - Bioadhesive systems interact with mucosal or tissue surfaces to enhance drug retention at the site of action.
Correct answer is: A particle that adheres to biological tissues, prolonging residence time
Q.70 When using a high‑shear homogenizer for emulsion preparation, increasing the shear rate generally results in:
Larger droplet size
Smaller droplet size
Higher polymer crystallinity
Increased polymer degradation
Explanation - Higher shear forces break larger droplets into finer ones, leading to smaller final particles.
Correct answer is: Smaller droplet size
Q.71 Which parameter is most directly affected by the porosity of a microparticle?
Drug loading capacity
Particle color
Electrical conductivity
Zeta potential
Explanation - Higher porosity provides more internal void space for drug accommodation.
Correct answer is: Drug loading capacity
Q.72 In drug delivery, what does the term 'targeted release' imply?
Release of drug only at a specific site or under a specific condition
Release of drug in any part of the body
Immediate release of the entire drug dose
Release only after the drug has been metabolized
Explanation - Targeted release aims to localize drug action, minimizing systemic exposure and side effects.
Correct answer is: Release of drug only at a specific site or under a specific condition
Q.73 Which of the following is a key advantage of using microencapsulation for volatile drugs?
Improves drug taste
Prevents evaporation during storage
Increases drug density
Reduces manufacturing cost
Explanation - Encapsulation isolates volatile compounds from the environment, reducing loss due to evaporation.
Correct answer is: Prevents evaporation during storage
Q.74 Which type of microparticle would be most suitable for delivering a drug that should be released only after enzymatic cleavage in the colon?
Microparticles made of alginate cross‑linked with calcium ions
Microparticles composed of PLGA
Microparticles coated with a pH‑sensitive polymer that dissolves at pH > 7
Microparticles containing enzyme‑sensitive peptide linkers
Explanation - Peptide linkers are cleaved by colonic enzymes, triggering drug release specifically in the colon.
Correct answer is: Microparticles containing enzyme‑sensitive peptide linkers
Q.75 What is the main purpose of adding a cryoprotectant such as trehalose before freeze‑drying microparticles?
To increase particle size
To prevent aggregation and preserve particle morphology
To enhance drug solubility
To change the drug's chemical structure
Explanation - Cryoprotectants protect particles from stress during freezing and sublimation, maintaining their size and shape.
Correct answer is: To prevent aggregation and preserve particle morphology
Q.76 Which of the following best describes a 'nanocomposite microparticle'?
A microparticle that contains dispersed nanoparticles within its matrix
A particle that is purely nanometer in size
A microparticle made entirely of inorganic material
A particle that changes color when exposed to light
Explanation - Nanocomposite microparticles embed nanoscale fillers to modify mechanical, thermal, or release properties.
Correct answer is: A microparticle that contains dispersed nanoparticles within its matrix
Q.77 Which analytical technique can be used to assess the moisture content of dried microparticles?
Karl Fischer titration
Differential scanning calorimetry (DSC)
X‑ray diffraction (XRD)
Nuclear magnetic resonance (NMR)
Explanation - Karl Fischer titration specifically quantifies water content in a sample.
Correct answer is: Karl Fischer titration
Q.78 In the context of drug delivery, what does the term 'pharmacokinetics' refer to?
The study of drug mechanisms of action
The study of drug absorption, distribution, metabolism, and excretion
The study of drug taste and odor
The study of drug manufacturing processes
Explanation - Pharmacokinetics describes how the body handles a drug over time.
Correct answer is: The study of drug absorption, distribution, metabolism, and excretion
Q.79 Which method can be used to produce microparticles with a narrow size distribution without using surfactants?
Microfluidic flow‑focusing device
Simple stirring in water
Melt extrusion
Spray drying with high inlet temperature
Explanation - Microfluidic devices generate monodisperse droplets by precise fluid control, eliminating the need for surfactants.
Correct answer is: Microfluidic flow‑focusing device
Q.80 Which polymer would be most appropriate for a microparticle intended to release a drug over several months?
Poly(lactic‑co‑glycolic acid) with 50:50 ratio and low molecular weight
Poly(lactic‑co‑glycolic acid) with 85:15 ratio and high molecular weight
Poly(vinyl alcohol) (PVA)
Cellulose acetate
Explanation - Higher lactide content and higher molecular weight slow degradation, extending release duration.
Correct answer is: Poly(lactic‑co‑glycolic acid) with 85:15 ratio and high molecular weight
Q.81 Which of the following is a typical reason for using a multilayer (core‑shell) microparticle design?
To increase the particle's magnetic properties
To provide separate control of drug loading (core) and release barrier (shell)
To make the particle larger than 1 mm
To simplify the manufacturing process
Explanation - Core‑shell structures enable independent optimization of drug loading and release kinetics.
Correct answer is: To provide separate control of drug loading (core) and release barrier (shell)
Q.82 When a microparticle formulation is described as 'hydrolytically degradable', what does this mean?
It degrades only in the presence of light
It degrades via cleavage of chemical bonds by water
It does not degrade at all
It degrades only under high temperature
Explanation - Hydrolytic degradation involves water molecules breaking polymer bonds, leading to polymer breakdown.
Correct answer is: It degrades via cleavage of chemical bonds by water
Q.83 Which of the following factors would most likely increase the initial burst release from a PLGA microparticle?
Increasing polymer crystallinity
Reducing the amount of drug adsorbed on the particle surface
Increasing the porosity of the particle
Using a higher molecular weight polymer
Explanation - More porous structures provide faster pathways for the drug to diffuse out, leading to a higher burst release.
Correct answer is: Increasing the porosity of the particle
Q.84 Which of the following best explains why microencapsulation can improve patient compliance?
It allows for fewer dosing frequencies due to sustained release
It makes the drug taste better
It reduces the cost of the drug
It changes the drug's color to a more appealing hue
Explanation - Sustained release formulations reduce the number of doses required, making therapy easier for patients.
Correct answer is: It allows for fewer dosing frequencies due to sustained release
Q.85 In an emulsion‑solvent evaporation method, what role does the continuous aqueous phase play?
It dissolves the polymer
It acts as a non‑solvent for the polymer, allowing precipitation of particles
It provides a source of surfactant
It reacts chemically with the drug
Explanation - The aqueous phase does not dissolve the polymer; when the organic solvent evaporates, the polymer precipitates as solid particles.
Correct answer is: It acts as a non‑solvent for the polymer, allowing precipitation of particles
Q.86 Which of the following is NOT a typical characteristic of a biodegradable polymer used in microparticle drug delivery?
It degrades into non‑toxic metabolites
It remains permanently in the body after drug release
Its degradation rate can be tailored by composition
It can be processed into various particle sizes
Explanation - Biodegradable polymers are designed to break down and be eliminated; permanence is contrary to their purpose.
Correct answer is: It remains permanently in the body after drug release
Q.87 Which factor most strongly affects the electrical conductivity of a polymeric microparticle composite used in EE applications?
Inclusion of conductive fillers such as carbon nanotubes
Particle color
Particle shape
Drug loading percentage
Explanation - Conductive fillers create percolation pathways that dramatically increase composite conductivity.
Correct answer is: Inclusion of conductive fillers such as carbon nanotubes
Q.88 What is the main advantage of using a 'pulsatile' drug release system in microencapsulation?
Continuous drug release at a constant rate
Release of drug in distinct bursts timed to physiological needs
Immediate release of the entire dose
Reduced need for any polymer
Explanation - Pulsatile systems aim to match the timing of drug release with circadian rhythms or disease flare‑ups.
Correct answer is: Release of drug in distinct bursts timed to physiological needs
Q.89 Which of the following is a typical method for sterilizing polymeric microparticle formulations intended for parenteral use?
Autoclaving at 121 °C
Gamma irradiation
Filtration through 0.2 µm membrane
Dry heating at 30 °C
Explanation - Gamma irradiation can sterilize heat‑sensitive powders without compromising polymer integrity.
Correct answer is: Gamma irradiation
Q.90 In a release study, a microparticle shows a linear increase in cumulative drug released versus time. Which kinetic model does this best represent?
Zero‑order kinetics
First‑order kinetics
Higuchi model
Korsmeyer‑Peppas model
Explanation - Zero‑order release gives a straight line when cumulative amount released is plotted against time.
Correct answer is: Zero‑order kinetics
Q.91 Which of the following polymers is known for its strong mucoadhesive properties due to its cationic nature?
Chitosan
Polyethylene glycol (PEG)
Polylactic acid (PLA)
Polycaprolactone (PCL)
Explanation - Chitosan carries positive charges that interact with negatively charged mucins, enhancing mucoadhesion.
Correct answer is: Chitosan
Q.92 When designing a microparticle for transdermal delivery, which characteristic is most critical?
Particle size below 10 µm to penetrate the stratum corneum
High density to sink in the formulation
Strong magnetic properties
Bright coloration for visual tracking
Explanation - Microparticles small enough can traverse the outer skin barrier, enabling drug delivery through the skin.
Correct answer is: Particle size below 10 µm to penetrate the stratum corneum
Q.93 Which method is commonly employed to achieve a high degree of uniformity in particle size for microparticles?
Batch stirring
Microfluidic droplet generation
Simple mixing with a spatula
Melt extrusion without cooling
Explanation - Microfluidic platforms produce highly monodisperse droplets leading to uniform particles.
Correct answer is: Microfluidic droplet generation
Q.94 A microparticle formulation contains a polymer that degrades by hydrolysis into lactic acid. Which of the following statements is true?
The polymer will become more hydrophobic as it degrades
The degradation products are acidic and may affect local pH
The polymer will not degrade in aqueous environments
The polymer will increase the drug's molecular weight
Explanation - Lactic acid is acidic; its accumulation can lower pH in the surrounding tissue, influencing drug stability and tissue response.
Correct answer is: The degradation products are acidic and may affect local pH
Q.95 Which of the following is the most appropriate technique to measure the amount of drug encapsulated inside microparticles after washing away surface drug?
Dissolve particles in a suitable solvent and analyze by HPLC
Measure particle size by laser diffraction
Observe particles under a light microscope
Determine zeta potential
Explanation - Solubilizing the particles releases the encapsulated drug, which can be quantified accurately using HPLC.
Correct answer is: Dissolve particles in a suitable solvent and analyze by HPLC
Q.96 Which factor most directly influences the mechanical strength of a compressed microparticle tablet?
Particle shape and size distribution
Particle color
Polymer glass transition temperature
Drug taste
Explanation - Uniform, spherical particles pack more efficiently and generate stronger tablets upon compression.
Correct answer is: Particle shape and size distribution
Q.97 For a microparticle intended to release a drug in response to an external electric field, which property must the particle possess?
Magnetic susceptibility
Electrical conductivity or dielectric responsiveness
High thermal conductivity
Photoluminescence
Explanation - Electrically responsive particles can change shape or permeability under an applied field, modulating drug release.
Correct answer is: Electrical conductivity or dielectric responsiveness
Q.98 Which of the following statements best describes the term 'bioerodible' in relation to microparticle systems?
The particles are resistant to enzymatic degradation
The particles degrade due to biological processes such as enzymatic action
The particles increase in size over time
The particles change color in biological fluids
Explanation - Bioerodible materials are designed to be broken down by enzymes or other biological mechanisms.
Correct answer is: The particles degrade due to biological processes such as enzymatic action
Q.99 Which analytical method would you use to verify that a protein maintains its secondary structure after encapsulation?
Circular dichroism (CD) spectroscopy
Thermogravimetric analysis (TGA)
Scanning electron microscopy (SEM)
Particle size analysis (laser diffraction)
Explanation - CD detects changes in protein secondary structure (α‑helix, β‑sheet) by measuring differential absorption of circularly polarized light.
Correct answer is: Circular dichroism (CD) spectroscopy
Q.100 Which of the following polymers is typically used to create pH‑responsive microparticles that swell at intestinal pH but remain collapsed in the stomach?
Eudragit® L100
Polyvinyl alcohol (PVA)
Polylactic acid (PLA)
Polystyrene (PS)
Explanation - Eudragit L100 dissolves at pH > 6, enabling swelling and drug release in the intestine while staying intact in the acidic stomach.
Correct answer is: Eudragit® L100
Q.101 Which of the following best explains why microparticles can improve the stability of a light‑sensitive drug?
Microparticles increase the drug's melting point
Encapsulation physically shields the drug from light exposure
Microparticles change the drug's chemical structure
Microparticles make the drug more soluble
Explanation - The polymeric matrix absorbs or scatters light, protecting the encapsulated drug from photodegradation.
Correct answer is: Encapsulation physically shields the drug from light exposure
Q.102 What is the primary function of a surfactant in the emulsion‑based preparation of microparticles?
To increase the polymer's molecular weight
To stabilize the dispersed phase and prevent coalescence
To act as a drug molecule
To change the color of the particles
Explanation - Surfactants reduce interfacial tension and keep droplets from merging, leading to uniform particle formation.
Correct answer is: To stabilize the dispersed phase and prevent coalescence
Q.103 Which property of a microparticle influences its ability to cross the blood‑brain barrier (BBB)?
Particle size below 200 nm
High surface charge (> +30 mV)
Bright coloration
Magnetic susceptibility
Explanation - Nanoparticles (often <200 nm) are more likely to traverse the BBB via transcytosis; larger microparticles are generally excluded.
Correct answer is: Particle size below 200 nm
Q.104 In the context of microparticle drug delivery, what does the term 'release exponent (n)' in the Korsmeyer‑Peppas model indicate?
The rate of polymer degradation
The mechanism of drug release (Fickian diffusion, anomalous transport, etc.)
The solubility of the drug
The particle's surface charge
Explanation - The exponent n helps classify release behavior: n≈0.5 (Fickian), 0.5<n<1 (anomalous), n=1 (zero‑order).
Correct answer is: The mechanism of drug release (Fickian diffusion, anomalous transport, etc.)
Q.105 Which of the following is a reason for adding a plasticizer to a polymeric microparticle formulation?
To increase the polymer's crystallinity
To reduce the polymer's glass transition temperature (Tg) and improve flexibility
To make the polymer magnetic
To raise the melting point of the polymer
Explanation - Plasticizers interpose between polymer chains, decreasing Tg and making the matrix more pliable.
Correct answer is: To reduce the polymer's glass transition temperature (Tg) and improve flexibility
Q.106 Which of the following best describes a 'controlled‑release' microparticle system?
A system that releases the entire drug load instantly
A system that releases drug at a predetermined rate over a specific period
A system that does not release any drug
A system that changes color when the drug is released
Explanation - Controlled‑release aims to maintain therapeutic levels by delivering drug at a designed rate.
Correct answer is: A system that releases drug at a predetermined rate over a specific period
Q.107 What is the main advantage of using a double‑emulsion (W/O/W) technique for encapsulating hydrophilic drugs compared to a single‑emulsion (O/W) method?
It eliminates the need for any polymer
It provides a higher encapsulation efficiency for water‑soluble drugs
It produces larger particles
It reduces the overall production cost
Explanation - The inner aqueous phase traps hydrophilic drugs, preventing them from diffusing out during processing.
Correct answer is: It provides a higher encapsulation efficiency for water‑soluble drugs
Q.108 Which polymer would be most suitable for preparing a microparticle that must remain stable in acidic gastric fluid but dissolve in the intestine?
Eudragit® S100
Polyvinyl alcohol (PVA)
Polyethylene glycol (PEG)
Polylactic acid (PLA)
Explanation - Eudragit S100 is designed to dissolve at pH > 7, making it stable in the stomach and soluble in the intestine.
Correct answer is: Eudragit® S100
Q.109 When performing in‑vitro release testing of microparticles, why is it important to maintain sink conditions?
To ensure the drug does not precipitate and the concentration gradient remains constant
To keep the temperature low
To prevent microbial growth
To maintain the pH at exactly 7.0
Explanation - Sink conditions keep drug concentration far below saturation, allowing release to be driven solely by the formulation.
Correct answer is: To ensure the drug does not precipitate and the concentration gradient remains constant
Q.110 Which analytical technique can directly measure the surface area of porous microparticles?
Brunauer–Emmett–Teller (BET) nitrogen adsorption
Fourier transform infrared spectroscopy (FTIR)
Nuclear magnetic resonance (NMR)
High‑performance liquid chromatography (HPLC)
Explanation - BET analysis quantifies surface area based on nitrogen gas adsorption onto the sample.
Correct answer is: Brunauer–Emmett–Teller (BET) nitrogen adsorption
Q.111 Which of the following best explains why microparticles are used in transdermal patches?
They increase the mechanical strength of the patch
They can provide controlled and sustained drug release through the skin
They make the patch more aesthetically pleasing
They allow the patch to be reused multiple times
Explanation - Microparticles embedded in a patch act as reservoirs that release drug at a regulated rate across the skin barrier.
Correct answer is: They can provide controlled and sustained drug release through the skin
Q.112 Which of the following statements is true regarding the effect of particle size on drug release from microparticles?
Larger particles always release drug faster than smaller particles
Smaller particles generally have a larger surface‑to‑volume ratio, leading to faster release
Particle size has no effect on release rate
Only the polymer type determines release, not particle size
Explanation - Higher surface area relative to volume enhances diffusion pathways, accelerating release.
Correct answer is: Smaller particles generally have a larger surface‑to‑volume ratio, leading to faster release
Q.113 Which property of a polymeric microparticle is most directly related to its ability to swell in aqueous media?
Hydrophilicity of the polymer
Particle color
Electrical conductivity
Magnetic susceptibility
Explanation - Hydrophilic polymers absorb water, causing swelling, while hydrophobic polymers resist it.
Correct answer is: Hydrophilicity of the polymer