Q.1 Which of the following mechanisms is primarily responsible for the initial burst release in polymeric drug‑delivery systems?
Diffusion through water‑filled pores
Polymer degradation
Swelling of the polymer matrix
Surface desorption of loosely bound drug
Explanation - The burst effect occurs when drug molecules located near or on the surface rapidly dissolve or detach, leading to a sudden increase in release rate.
Correct answer is: Surface desorption of loosely bound drug
Q.2 In a zero‑order controlled‑release system, the drug release rate is:
Proportional to the concentration gradient
Constant over time
Decreasing exponentially
Dependent on polymer degradation
Explanation - Zero‑order kinetics imply a constant release rate irrespective of the drug concentration remaining in the device.
Correct answer is: Constant over time
Q.3 Which polymer is commonly used for biodegradable, sustained‑release implants due to its hydrolytic degradation?
Polyethylene glycol (PEG)
Polylactic‑co‑glycolic acid (PLGA)
Polystyrene (PS)
Polyvinyl chloride (PVC)
Explanation - PLGA hydrolyzes into lactic and glycolic acid, making it suitable for biodegradable implantable drug‑delivery systems.
Correct answer is: Polylactic‑co‑glycolic acid (PLGA)
Q.4 The Higuchi model for drug release from a matrix assumes which of the following conditions?
Constant diffusion coefficient and a pseudo‑steady state
First‑order degradation of the polymer
Zero‑order release kinetics
Swelling of the matrix
Explanation - The Higuchi equation is derived under the assumptions of a constant diffusion coefficient, uniform initial drug distribution, and a pseudo‑steady‑state diffusion front.
Correct answer is: Constant diffusion coefficient and a pseudo‑steady state
Q.5 Which of the following is a major advantage of using osmotic pump systems for controlled drug delivery?
They require no power source
They provide pulsatile release profiles
They are independent of external pH
They can achieve zero‑order release over long periods
Explanation - Osmotic pumps use osmotic pressure to drive a constant flow of drug solution, enabling near zero‑order release for extended durations.
Correct answer is: They can achieve zero‑order release over long periods
Q.6 In a drug‑eluting stent, the primary factor controlling the drug release rate is:
Stent diameter
Polymer coating thickness
Blood flow velocity
Patient’s metabolism
Explanation - The thickness and composition of the polymer coating dictate diffusion path length and hence the drug release kinetics.
Correct answer is: Polymer coating thickness
Q.7 Which mathematical model best describes drug release from a spherical biodegradable polymer particle where degradation dominates the release mechanism?
Korsmeyer‑Peppas model
Higuchi model
First‑order kinetic model
Zero‑order kinetic model
Explanation - The Korsmeyer‑Peppas equation accounts for both diffusion and polymer erosion, fitting well to spherical particles with degradation‑controlled release.
Correct answer is: Korsmeyer‑Peppas model
Q.8 What is the main purpose of adding a permeation enhancer to a transdermal patch?
To increase the patch’s mechanical strength
To reduce drug degradation
To improve drug solubility in the patch matrix
To increase drug flux across the skin
Explanation - Permeation enhancers temporarily disrupt the stratum corneum, facilitating greater drug permeation through the skin.
Correct answer is: To increase drug flux across the skin
Q.9 Which of the following is NOT a typical method for fabricating microspheres used in sustained drug release?
Emulsion‑solvent evaporation
Spray drying
Melt extrusion
Layer‑by‑layer deposition
Explanation - Layer‑by‑layer deposition is generally employed for thin films, not for forming microspheres; the other methods are standard microsphere techniques.
Correct answer is: Layer‑by‑layer deposition
Q.10 A drug‑delivery system that releases drug in response to a specific physiological trigger (e.g., pH change) is called:
Passive release system
Stimuli‑responsive system
Reservoir system
Matrix system
Explanation - Stimuli‑responsive (or smart) systems alter release rates in response to internal or external triggers such as pH, temperature, or enzymes.
Correct answer is: Stimuli‑responsive system
Q.11 In the context of controlled release, the term ‘lag time’ refers to:
The period before drug reaches therapeutic concentration
The time required for polymer degradation
The duration of the burst release phase
The interval between two dosing events
Explanation - Lag time is the initial delay before a measurable amount of drug is released, often due to diffusion barriers or swelling.
Correct answer is: The period before drug reaches therapeutic concentration
Q.12 Which of the following factors most significantly affects the diffusion coefficient of a drug in a polymer matrix?
Molecular weight of the polymer
Drug’s solubility in the polymer
Polymer’s glass transition temperature (Tg)
Device shape
Explanation - Higher drug solubility in the polymer matrix generally leads to a larger diffusion coefficient, enhancing release rates.
Correct answer is: Drug’s solubility in the polymer
Q.13 Which of the following is a key advantage of using ion‑exchange resins in oral sustained‑release formulations?
They provide immediate drug release
They protect drug from gastric acidity
They allow controlled release via ion exchange with gastrointestinal fluids
They enhance drug permeability across the intestinal wall
Explanation - Ion‑exchange resins release the drug as counter‑ions in the GI tract replace the drug‑bound ions, providing a sustained‑release effect.
Correct answer is: They allow controlled release via ion exchange with gastrointestinal fluids
Q.14 A biodegradable polymer that exhibits bulk erosion releases drug primarily by:
Surface erosion of polymer layers
Diffusion through water‑filled pores
Swelling and subsequent diffusion
Uniform degradation throughout the matrix
Explanation - Bulk erosion means the polymer degrades uniformly throughout its volume, releasing drug as the matrix dissolves.
Correct answer is: Uniform degradation throughout the matrix
Q.15 Which of the following is a limitation of matrix‑type sustained‑release tablets compared to reservoir‑type tablets?
Higher manufacturing cost
Less flexibility in modifying release rate after production
Inability to incorporate high drug loads
Requirement of a sealing coat
Explanation - Matrix tablets have the drug dispersed throughout; once fabricated, adjusting the release profile is difficult compared to reservoir systems with a distinct coating.
Correct answer is: Less flexibility in modifying release rate after production
Q.16 In an electrospun nanofiber drug‑delivery system, the primary parameter that controls fiber diameter (and thus drug release) is:
Solution viscosity
Collector distance
Ambient temperature
Polymer molecular weight
Explanation - Higher viscosity leads to thicker fibers, increasing diffusion path length and slowing drug release.
Correct answer is: Solution viscosity
Q.17 For a drug with a short half‑life, which sustained‑release strategy is most appropriate to maintain therapeutic levels?
Immediate‑release tablets taken multiple times daily
Implantable biodegradable matrix
Enteric‑coated tablets
Orally disintegrating tablets
Explanation - An implant can provide continuous, controlled release over days to weeks, ideal for drugs with short systemic half‑lives.
Correct answer is: Implantable biodegradable matrix
Q.18 Which of the following best describes the ‘reservoir’ design in a transdermal patch?
Drug is uniformly dispersed throughout the adhesive matrix
Drug is stored in a separate layer beneath a rate‑controlling membrane
Drug is chemically bound to the backing layer
Drug is present as discrete micro‑reservoirs within the patch
Explanation - Reservoir patches contain a drug‑filled chamber separated from the skin by a membrane that controls diffusion.
Correct answer is: Drug is stored in a separate layer beneath a rate‑controlling membrane
Q.19 Which of the following release profiles is characteristic of a first‑order kinetic system?
A straight line when cumulative amount released is plotted versus time
A straight line when log cumulative remaining drug is plotted versus time
A constant amount of drug released per unit time
An initial burst followed by a plateau
Explanation - First‑order release results in exponential decay of the drug amount, giving a linear relationship on a semi‑log plot.
Correct answer is: A straight line when log cumulative remaining drug is plotted versus time
Q.20 The primary function of a rate‑controlling membrane in a drug‑eluting stent is to:
Provide mechanical support to the artery
Prevent blood clot formation
Regulate drug diffusion to achieve sustained release
Enhance the stent’s radiopacity
Explanation - The membrane's permeability determines the drug flux, allowing controlled, prolonged therapeutic delivery.
Correct answer is: Regulate drug diffusion to achieve sustained release
Q.21 Which of the following statements about polymer swelling in hydrogel drug carriers is true?
Swelling always accelerates drug release
Swelling can create a diffusion pathway for drug molecules
Swelling reduces the water content in the matrix
Swelling is independent of environmental pH
Explanation - Hydrogel swelling absorbs water, enlarging pores and facilitating drug diffusion.
Correct answer is: Swelling can create a diffusion pathway for drug molecules
Q.22 A drug‑delivery system that releases drug at a rate proportional to the surface area of the device is governed by which kinetic model?
Higuchi model
Korsmeyer‑Peppas model (n = 0.5)
Zero‑order model
First‑order model
Explanation - For a thin film or slab where diffusion dominates, the exponent n = 0.5 corresponds to Fickian diffusion, giving surface‑area‑dependent release.
Correct answer is: Korsmeyer‑Peppas model (n = 0.5)
Q.23 In a double‑layer tablet designed for biphasic release, the inner layer typically contains:
Immediate‑release drug
Enteric coating material
Sustained‑release polymer matrix
Flavoring agents
Explanation - The outer layer provides rapid release, while the inner layer is formulated for prolonged drug delivery.
Correct answer is: Sustained‑release polymer matrix
Q.24 Which analytical technique is most suitable for measuring the in‑vitro release profile of a biodegradable implant?
Scanning electron microscopy (SEM)
High‑performance liquid chromatography (HPLC)
Fourier‑transform infrared spectroscopy (FTIR)
Differential scanning calorimetry (DSC)
Explanation - HPLC quantifies drug concentration in release media over time, providing accurate release kinetics.
Correct answer is: High‑performance liquid chromatography (HPLC)
Q.25 The term ‘bioavailability’ in the context of sustained‑release formulations primarily refers to:
The total amount of drug released from the device
The fraction of administered drug that reaches systemic circulation
The rate at which drug is released from the matrix
The stability of the drug within the delivery system
Explanation - Bioavailability is the proportion of the administered dose that reaches the systemic circulation in an active form.
Correct answer is: The fraction of administered drug that reaches systemic circulation
Q.26 In a polymeric microsphere, which factor most directly influences the initial lag time before drug release begins?
Polymer glass transition temperature
Particle size
Drug loading concentration
Presence of a coating layer
Explanation - A coating creates an additional diffusion barrier, extending the lag time before drug can diffuse out.
Correct answer is: Presence of a coating layer
Q.27 Which of the following is a common cause of ‘dose dumping’ in sustained‑release tablets?
Improper storage at high humidity
Excessive compression force during tablet manufacture
Use of a non‑enteric coating in acidic environments
All of the above
Explanation - Each listed factor can compromise the integrity of the release-controlling matrix, leading to rapid, uncontrolled release (dose dumping).
Correct answer is: All of the above
Q.28 For a drug with poor aqueous solubility, which sustained‑release approach can improve its bioavailability?
Encapsulation in lipid‑based nanoparticles
Use of a high‑density polymer matrix
Incorporation into a hard gelatin capsule
Addition of a sweetener
Explanation - Lipid carriers enhance solubility and can provide controlled release, improving overall bioavailability.
Correct answer is: Encapsulation in lipid‑based nanoparticles
Q.29 The term ‘erosion‑controlled release’ best describes which type of system?
Matrix systems where drug diffuses through pores
Systems where polymer degradation governs drug release
Osmotic pump systems
Reservoir systems with impermeable walls
Explanation - Erosion‑controlled release relies on polymer breakdown (surface or bulk) to liberate the drug.
Correct answer is: Systems where polymer degradation governs drug release
Q.30 Which of the following is NOT a typical trigger for a stimuli‑responsive drug delivery system?
pH changes
Temperature fluctuations
Magnetic field exposure
Gravitational force
Explanation - Gravitational force does not induce a molecular change in the carrier; pH, temperature, and magnetic fields are common stimuli.
Correct answer is: Gravitational force
Q.31 In a bilayer patch where the top layer is drug‑free and the bottom layer contains drug, which phenomenon primarily determines the drug’s release rate?
Diffusion through the drug‑free layer
Swelling of the drug‑containing layer
Erosion of the backing material
Electrostatic attraction between layers
Explanation - The drug must first diffuse across the drug‑free layer, making its permeability the rate‑limiting step.
Correct answer is: Diffusion through the drug‑free layer
Q.32 Which of the following parameters can be tuned to achieve a longer duration of action in a biodegradable implant?
Increasing the drug’s molecular weight
Reducing polymer molecular weight
Using a polymer with a faster degradation rate
Increasing the surface area of the implant
Explanation - Higher molecular weight drugs generally have lower diffusion coefficients, extending release duration; polymer characteristics also matter, but the question focuses on drug properties.
Correct answer is: Increasing the drug’s molecular weight
Q.33 A drug‑delivery system that uses a semi‑permeable membrane to allow water influx and drug efflux is known as:
Reservoir system
Matrix system
Osmotic pump
Ion‑exchange system
Explanation - Osmotic pumps employ a semi‑permeable membrane that permits water entry, generating osmotic pressure that pushes drug solution out at a controlled rate.
Correct answer is: Osmotic pump
Q.34 Which drug‑delivery technology is commonly employed for intravitreal injection to provide sustained release in the eye?
Poly(lactic‑co‑glycolic acid) microspheres
Transdermal patches
Enteric coated tablets
Implantable metallic stents
Explanation - PLGA microspheres are biodegradable, injectable, and provide long‑term drug release within the vitreous humor.
Correct answer is: Poly(lactic‑co‑glycolic acid) microspheres
Q.35 In the context of controlled drug delivery, the term “bioerodible” refers to:
Materials that dissolve upon exposure to light
Polymers that degrade in response to biological conditions
Coatings that swell in the presence of moisture
Devices that release drug only after enzymatic activation
Explanation - Biodegradable (bioerodible) polymers break down via hydrolysis or enzymatic action within the body.
Correct answer is: Polymers that degrade in response to biological conditions
Q.36 The primary reason for incorporating a plasticizer into a polymeric film for drug delivery is to:
Increase the mechanical strength of the film
Accelerate polymer degradation
Enhance drug solubility in the film
Reduce the glass transition temperature (Tg) and increase flexibility
Explanation - Plasticizers lower Tg, making the polymer more flexible and often improving drug diffusion.
Correct answer is: Reduce the glass transition temperature (Tg) and increase flexibility
Q.37 A drug‑eluting contact lens aims to deliver medication to the eye over several days. Which factor most critically controls the release rate?
Lens thickness
Water content of the hydrogel
Color of the lens
Shape of the lens
Explanation - Higher water content increases drug diffusion through the hydrogel matrix, directly influencing release kinetics.
Correct answer is: Water content of the hydrogel
Q.38 Which of the following is a typical advantage of using micro‑needles for transdermal sustained release?
Pain‑free administration
Ability to deliver large volumes of drug
No need for a drug‑carrier matrix
Elimination of drug degradation
Explanation - Micro‑needles penetrate the stratum corneum with minimal pain, providing a route for sustained delivery of drugs.
Correct answer is: Pain‑free administration
Q.39 In a multi‑layered tablet designed for sequential release, the middle layer typically functions as:
A barrier to prevent drug–drug interaction
An immediate‑release excipient
A swelling agent to create lag time
A protective coating against gastric acid
Explanation - The middle layer isolates distinct drug layers, allowing sequential release without interference.
Correct answer is: A barrier to prevent drug–drug interaction
Q.40 Which kinetic model is most appropriate for describing drug release from a spherical reservoir with a non‑degrading membrane?
Higuchi model
Korsmeyer‑Peppas model
First‑order model
Zero‑order model
Explanation - A non‑degrading membrane with constant surface area can sustain a constant release rate, fitting zero‑order kinetics.
Correct answer is: Zero‑order model
Q.41 The term ‘hydrophilic matrix’ in oral controlled‑release tablets refers to:
A polymer that dissolves quickly upon contact with water
A polymer that swells and forms a gel barrier
A polymer that is completely insoluble in water
A polymer that releases drug via erosion only
Explanation - Hydrophilic polymers (e.g., HPMC) absorb water, swell, and create a gel layer that controls drug diffusion.
Correct answer is: A polymer that swells and forms a gel barrier
Q.42 Which of the following is a key factor influencing the rate of drug diffusion through a polymeric membrane?
Polymer crystallinity
Drug's pKa
Device color
Manufacturing location
Explanation - Higher crystallinity reduces free volume and hampers diffusion, lowering release rates.
Correct answer is: Polymer crystallinity
Q.43 For a drug delivered via an intramuscular depot injection, the main mechanism governing prolonged release is:
Rapid diffusion into bloodstream
Polymer erosion and drug diffusion
Osmotic pressure
Ion‑exchange with muscle tissue
Explanation - Depot formulations typically use biodegradable polymers; as the polymer erodes, drug diffuses out over weeks or months.
Correct answer is: Polymer erosion and drug diffusion
Q.44 A major drawback of using high‑dose polymeric implants for sustained release is:
Limited drug stability
Potential for foreign‑body reaction
Rapid drug release
Inability to sterilize
Explanation - Large implants can provoke chronic inflammation or fibrosis, compromising safety and efficacy.
Correct answer is: Potential for foreign‑body reaction
Q.45 Which of the following best describes a ‘pulsatile’ drug‑release system?
A system that releases drug at a constant rate
A system that releases drug in bursts separated by lag periods
A system that releases drug only when a magnetic field is applied
A system that releases drug only at night
Explanation - Pulsatile systems mimic circadian rhythms or dosing schedules by delivering discrete doses at predetermined times.
Correct answer is: A system that releases drug in bursts separated by lag periods
Q.46 In a polymeric matrix tablet, increasing the proportion of a highly water‑soluble filler (e.g., lactose) will most likely:
Decrease the overall drug release rate
Increase the burst effect
Make the tablet harder
Prevent drug degradation
Explanation - A soluble filler creates pores as it dissolves, facilitating faster drug diffusion and a larger initial burst.
Correct answer is: Increase the burst effect
Q.47 Which property of a drug most directly affects its suitability for transdermal sustained‑release delivery?
High molecular weight (>500 Da)
Low lipophilicity
Optimal log P between 1 and 3
Rapid renal clearance
Explanation - Transdermal drugs require moderate lipophilicity (log P 1‑3) to partition into the stratum corneum and diffuse through the skin.
Correct answer is: Optimal log P between 1 and 3
Q.48 The primary purpose of a ‘sealant’ layer in a reservoir-type sustained‑release tablet is to:
Increase tablet hardness
Prevent premature drug leakage
Improve taste masking
Enhance drug solubility
Explanation - The sealant forms an impermeable barrier, ensuring that drug release occurs only via the designed rate‑controlling membrane.
Correct answer is: Prevent premature drug leakage
Q.49 Which of the following is an example of a biodegradable polymer used in injectable sustained‑release formulations?
Polyvinyl acetate
Polylactic acid (PLA)
Polyethylene terephthalate (PET)
Polymethyl methacrylate (PMMA)
Explanation - PLA hydrolyzes in vivo, making it suitable for injectable depots that gradually release drug as the polymer degrades.
Correct answer is: Polylactic acid (PLA)
Q.50 In a drug‑eluting stent, the term ‘elution rate’ is most directly affected by:
Stent strut thickness
Polymer coating porosity
Patient’s blood pressure
Stent deployment pressure
Explanation - Higher porosity allows faster diffusion of the drug through the coating, increasing the elution rate.
Correct answer is: Polymer coating porosity
Q.51 A sustained‑release formulation that releases drug primarily by dissolution of the carrier material is classified as:
Diffusion controlled
Erosion controlled
Osmotic controlled
Ion‑exchange controlled
Explanation - Erosion‑controlled systems rely on carrier dissolution or degradation to free the drug.
Correct answer is: Erosion controlled
Q.52 Which of the following best explains why a drug with a short half‑life may benefit from a sustained‑release formulation?
To increase the drug’s potency
To reduce dosing frequency and maintain steady plasma levels
To alter the drug’s mechanism of action
To change the route of administration
Explanation - Sustained release smooths plasma concentration fluctuations, reducing peaks and troughs associated with short‑half‑life drugs.
Correct answer is: To reduce dosing frequency and maintain steady plasma levels
Q.53 Which parameter is most critical when designing a nanoparticle for controlled drug release via the enhanced permeability and retention (EPR) effect?
Particle charge
Particle size around 100‑200 nm
Surface roughness
Magnetic susceptibility
Explanation - Nanoparticles of 100‑200 nm can preferentially accumulate in tumor tissue via the EPR effect, aiding sustained delivery.
Correct answer is: Particle size around 100‑200 nm
Q.54 In a diffusion‑controlled matrix tablet, increasing the polymer’s cross‑link density will:
Accelerate drug release
Slow down drug release
Have no effect on drug release
Cause immediate burst release
Explanation - Higher cross‑link density reduces mesh size, limiting drug diffusion and thus slowing release.
Correct answer is: Slow down drug release
Q.55 Which of the following best characterizes a ‘reservoir‑type’ implant?
Drug dispersed uniformly throughout the polymer
Drug stored in a central core surrounded by a rate‑controlling membrane
Drug chemically bonded to the implant surface
Drug encapsulated in liposomes within the implant
Explanation - Reservoir implants contain a distinct drug core, and release is modulated by the surrounding membrane.
Correct answer is: Drug stored in a central core surrounded by a rate‑controlling membrane
Q.56 A key benefit of using a biodegradable polymer in a sustained‑release ocular insert is:
Elimination of the need for surgical removal
Enhanced optical clarity
Instantaneous drug release
Increased rigidity of the insert
Explanation - Biodegradable inserts degrade in situ, removing the requirement for extraction after therapy completes.
Correct answer is: Elimination of the need for surgical removal
Q.57 The term ‘steady‑state flux’ in an osmotic pump refers to:
The initial burst of drug released
A constant rate of drug passage through the membrane after equilibration
The total amount of drug released over the device’s life
The rate of water influx into the device
Explanation - Steady‑state flux is the uniform drug flow achieved once osmotic pressure and membrane resistance stabilize.
Correct answer is: A constant rate of drug passage through the membrane after equilibration
Q.58 Which of the following is a common analytical method for assessing polymer degradation kinetics in vitro?
Gel permeation chromatography (GPC)
Atomic absorption spectroscopy (AAS)
X‑ray diffraction (XRD)
UV‑Vis spectroscopy of degradation products
Explanation - GPC measures molecular weight distribution over time, providing direct insight into polymer chain scission during degradation.
Correct answer is: Gel permeation chromatography (GPC)
Q.59 In a pH‑responsive hydrogel designed for colon‑targeted delivery, the polymer remains swollen at pH > 7.0 because:
Acidic groups become de‑protonated, increasing electrostatic repulsion
Cross‑links are broken by basic conditions
The polymer dissolves completely
Water is excluded from the matrix at high pH
Explanation - De‑protonation of carboxylic acids at higher pH leads to ionization, swelling, and enhanced drug release.
Correct answer is: Acidic groups become de‑protonated, increasing electrostatic repulsion
Q.60 Which of the following is a primary consideration when selecting a polymer for a heat‑sterilized sustained‑release implant?
Polymer’s melting point must be below sterilization temperature
Polymer must be highly crystalline
Polymer must be electrically conductive
Polymer must be opaque
Explanation - Heat sterilization can degrade polymers with low melting points; the polymer must retain integrity at the sterilization temperature.
Correct answer is: Polymer’s melting point must be below sterilization temperature
Q.61 A drug‑delivery system that releases drug via a reversible chemical reaction triggered by glucose is an example of:
pH‑responsive system
Enzyme‑responsive system
Glucose‑responsive (smart) system
Thermo‑responsive system
Explanation - Glucose‑responsive carriers detect blood glucose levels and adjust drug release accordingly, useful for insulin delivery.
Correct answer is: Glucose‑responsive (smart) system
Q.62 When modeling drug release from a cylindrical matrix, which geometric factor must be considered?
Surface‑to‑volume ratio
Aspect ratio of length to diameter
Curvature of the ends
All of the above
Explanation - Cylindrical geometry influences diffusion paths via surface‑to‑volume ratio, aspect ratio, and end curvature.
Correct answer is: All of the above
Q.63 Which of the following best explains why a drug with high water solubility may be challenging to formulate as a sustained‑release tablet?
It will rapidly dissolve and diffuse out of the matrix
It is unstable in the gastrointestinal tract
It cannot be mixed with polymers
It requires a higher manufacturing temperature
Explanation - High solubility accelerates diffusion, leading to a faster release profile and difficulty achieving sustained release.
Correct answer is: It will rapidly dissolve and diffuse out of the matrix
Q.64 In the context of drug‑eluting stents, the term ‘restenosis’ refers to:
Re‑occlusion of the artery due to tissue overgrowth
Corrosion of the stent material
Degradation of the polymer coating
Thrombosis formation in the stent lumen
Explanation - Restenosis is the re‑narrowing of the vessel caused by neointimal hyperplasia; drug‑eluting stents aim to reduce this.
Correct answer is: Re‑occlusion of the artery due to tissue overgrowth
Q.65 Which of the following is a typical reason for using a “burst‑release” layer in a multi‑layered controlled‑release tablet?
To mask the taste of the drug
To achieve rapid onset of therapeutic effect
To increase tablet hardness
To prevent drug degradation
Explanation - A burst layer releases a portion of the dose quickly, providing an immediate therapeutic level before sustained release continues.
Correct answer is: To achieve rapid onset of therapeutic effect
Q.66 The main advantage of using a “matrix‑type” oral dosage form over a “reservoir‑type” is:
Simpler manufacturing process
Higher drug loading capacity
Ability to achieve perfect zero‑order release
Reduced risk of dose dumping
Explanation - Matrix tablets are typically produced by direct compression or granulation, making them easier and cheaper to manufacture.
Correct answer is: Simpler manufacturing process
Q.67 Which of the following mechanisms is primarily responsible for drug release from a thermosensitive hydrogel that transitions from sol to gel at body temperature?
Diffusion through the gel network
Polymer erosion
Osmotic pressure
Ion exchange
Explanation - After gelation, the drug diffuses through the formed hydrogel matrix; erosion may be minimal if the polymer is stable.
Correct answer is: Diffusion through the gel network
Q.68 For a controlled‑release system designed to deliver a peptide drug, which barrier is most critical to overcome?
Blood‑brain barrier
Gastrointestinal enzymatic degradation
Skin stratum corneum
Renal filtration
Explanation - Peptide drugs are susceptible to proteolysis in the GI tract, so delivery systems must protect them from enzymatic breakdown.
Correct answer is: Gastrointestinal enzymatic degradation
Q.69 Which of the following best describes the purpose of a “lag‑time” modifier (e.g., a coating) in a sustained‑release tablet?
To speed up drug release
To delay the onset of drug release
To increase drug solubility
To improve tablet color
Explanation - Lag‑time modifiers create an initial barrier that postpones drug diffusion, useful for chronotherapy.
Correct answer is: To delay the onset of drug release
Q.70 When designing a micro‑particle for pulmonary delivery with sustained release, the optimal aerodynamic diameter is:
1‑3 µm
5‑10 µm
10‑15 µm
20‑30 µm
Explanation - Particles in the 1‑3 µm range have suitable aerodynamic properties to reach the alveolar region and remain there for prolonged release.
Correct answer is: 1‑3 µm
Q.71 In a drug‑loaded polymeric scaffold for tissue engineering, sustained release is primarily achieved through:
Rapid dissolution of the scaffold
Diffusion of drug through the porous matrix
Electrical stimulation of the scaffold
Magnetic field activation
Explanation - Porous scaffolds provide diffusion pathways for the embedded drug, enabling a sustained release while supporting tissue growth.
Correct answer is: Diffusion of drug through the porous matrix
Q.72 Which of the following polymers is commonly used to create a pH‑responsive coating for enteric tablets?
Cellulose acetate phthalate (CAP)
Polyvinyl alcohol (PVA)
Polystyrene (PS)
Polyethylene glycol (PEG)
Explanation - CAP dissolves at intestinal pH (≈6‑7), protecting the drug in the acidic stomach environment.
Correct answer is: Cellulose acetate phthalate (CAP)
Q.73 When a drug‑delivery device is described as having ‘first‑order release kinetics’, the rate of drug release:
Is constant over time
Decreases exponentially with remaining drug amount
Increases with time
Is independent of drug concentration
Explanation - First‑order kinetics imply that the release rate is proportional to the amount of drug remaining in the device.
Correct answer is: Decreases exponentially with remaining drug amount
Q.74 A common drawback of matrix tablets containing a high fraction of hydrophobic polymer is:
Very fast drug release
Potential for incomplete drug release (dose dumping)
Reduced mechanical strength
Increased burst effect
Explanation - Hydrophobic polymers can impede water penetration, leading to incomplete or erratic drug release.
Correct answer is: Potential for incomplete drug release (dose dumping)
Q.75 In a sustained‑release formulation, the term ‘permeability coefficient’ (P) describes:
The rate at which a polymer degrades
The ability of a drug to diffuse through a membrane
The solubility of the drug in water
The mechanical strength of the device
Explanation - P = D·K (diffusion coefficient × partition coefficient) quantifies drug transport across a barrier.
Correct answer is: The ability of a drug to diffuse through a membrane
Q.76 Which of the following best explains why a drug‑eluting stent may use a mixture of fast‑ and slow‑degrading polymers?
To achieve a biphasic release profile with an initial high dose followed by a maintenance dose
To reduce the cost of the device
To increase the stent’s radial strength
To simplify the manufacturing process
Explanation - Combining polymers with different degradation rates provides an early burst and a prolonged release phase.
Correct answer is: To achieve a biphasic release profile with an initial high dose followed by a maintenance dose
Q.77 When formulating a long‑acting injectable (LAI), which property of the drug is most important to ensure a low initial burst release?
High aqueous solubility
Low melting point
Low diffusion coefficient in the polymer
High molecular weight
Explanation - A low diffusion coefficient restricts rapid drug movement out of the depot, minimizing burst release.
Correct answer is: Low diffusion coefficient in the polymer
Q.78 In the design of a gastroretentive tablet for sustained release, which mechanism helps the dosage form stay in the stomach?
Floating via low density
Swelling to a size larger than the pyloric opening
Magnetic attraction to gastric walls
Chemical adhesion to gastric mucosa
Explanation - Low‑density tablets float on gastric fluids, prolonging gastric residence time and enabling sustained release.
Correct answer is: Floating via low density
Q.79 Which of the following is a primary factor influencing the rate of drug release from a polymeric nanofiber mat?
Nanofiber orientation
Fiber diameter
Nanofiber color
Manufacturing country
Explanation - Smaller fiber diameters increase surface area and reduce diffusion path length, accelerating release.
Correct answer is: Fiber diameter
Q.80 A drug‑delivery system that releases drug only when exposed to a specific wavelength of light is known as:
pH‑responsive system
Thermo‑responsive system
Photo‑responsive (phototriggered) system
Magnetically‑responsive system
Explanation - Phototriggered systems use light as an external stimulus to initiate drug release.
Correct answer is: Photo‑responsive (phototriggered) system
Q.81 In a controlled‑release formulation, the term ‘matrix erosion’ is most closely associated with which polymer behavior?
Surface swelling without mass loss
Uniform bulk degradation throughout the polymer
Formation of pores due to solvent leaching
Chemical bonding of drug to polymer chains
Explanation - Matrix erosion involves the polymer losing mass uniformly, allowing drug release as the matrix degrades.
Correct answer is: Uniform bulk degradation throughout the polymer
Q.82 Which of the following analytical methods can directly measure the diffusion coefficient of a drug within a polymer matrix?
Differential scanning calorimetry (DSC)
Rheometry
Franz diffusion cell studies
Thermogravimetric analysis (TGA)
Explanation - Franz cells allow quantification of drug flux across a polymer film, from which diffusion coefficients can be derived.
Correct answer is: Franz diffusion cell studies
Q.83 A polymer that exhibits a glass transition temperature (Tg) below body temperature will:
Remain glassy and rigid in vivo
Be in a rubbery, flexible state in vivo
Rapidly degrade upon implantation
Prevent any drug diffusion
Explanation - When Tg < body temperature, the polymer is above its Tg and thus in a flexible, rubbery state, facilitating diffusion.
Correct answer is: Be in a rubbery, flexible state in vivo
Q.84 In a sustained‑release oral dosage form, the term ‘washout period’ refers to:
The time needed to flush out the device after removal
The interval between dosing cycles in a crossover study
The period after administration when no drug is detected in plasma
The lag time before the drug begins to be released
Explanation - Washout period describes the time needed for the drug to be eliminated from the body before the next dosing phase in studies.
Correct answer is: The period after administration when no drug is detected in plasma
Q.85 Which of the following is a common approach to reduce the burst effect in a matrix tablet?
Increasing the proportion of a highly soluble filler
Using a polymer with a higher degree of cross‑linking
Adding more water to the formulation
Decreasing tablet hardness
Explanation - Higher cross‑link density reduces pore formation and limits rapid drug diffusion, mitigating the burst effect.
Correct answer is: Using a polymer with a higher degree of cross‑linking
Q.86 A biodegradable implant designed for weekly drug release would most likely use a polymer with:
Very rapid hydrolytic degradation (days)
Very slow degradation (years)
Intermediate degradation rate (weeks)
No degradation at all
Explanation - To sustain weekly release, the polymer should degrade at a rate that aligns with the desired dosing interval.
Correct answer is: Intermediate degradation rate (weeks)
Q.87 Which of the following best describes why a drug‑delivery device may incorporate a “rate‑controlling membrane” made of a non‑degradable polymer?
To ensure that drug release is governed solely by diffusion
To allow the membrane to dissolve after drug depletion
To provide a biodegradable scaffold for tissue ingrowth
To increase the device’s electrical conductivity
Explanation - A non‑degradable membrane remains intact, making diffusion the primary controlling mechanism for drug release.
Correct answer is: To ensure that drug release is governed solely by diffusion
Q.88 When evaluating the in‑vitro release profile of a sustained‑release formulation, the term “sink conditions” means:
The release medium is saturated with the drug
The concentration of drug in the medium is kept well below its solubility limit
The device is placed in a closed system with no fluid exchange
The temperature of the medium is constantly changing
Explanation - Sink conditions ensure that the drug concentration gradient remains maximal, providing accurate assessment of release kinetics.
Correct answer is: The concentration of drug in the medium is kept well below its solubility limit
Q.89 Which of the following strategies can be employed to achieve a very low initial burst followed by a long‑term release in a polymeric microsphere?
Coating microspheres with a thin polymer layer
Increasing the drug loading to 90 %
Using a highly porous polymer matrix
Adding a surfactant to the formulation
Explanation - A coating acts as an additional diffusion barrier, suppressing the burst and allowing a more gradual release.
Correct answer is: Coating microspheres with a thin polymer layer
Q.90 In the context of drug delivery, the term “bioadhesive” refers to:
A material that adheres to biological tissues to prolong residence time
A polymer that degrades rapidly in vivo
A coating that prevents drug release
A device that releases drug only upon electrical stimulation
Explanation - Bioadhesive polymers increase contact time with mucosal surfaces, enhancing drug absorption.
Correct answer is: A material that adheres to biological tissues to prolong residence time
Q.91 Which of the following best describes the effect of increasing the polymer’s molecular weight on drug diffusion in a matrix system?
Increases diffusion coefficient
Decreases diffusion coefficient
Has no effect on diffusion
Causes polymer to become crystalline
Explanation - Higher molecular weight polymers have tighter chain packing, reducing free volume and slowing drug diffusion.
Correct answer is: Decreases diffusion coefficient
Q.92 A drug‑delivery system that releases a drug in response to elevated glucose levels is primarily intended for treating:
Hypertension
Diabetes mellitus
Asthma
Alzheimer’s disease
Explanation - Glucose‑responsive systems sense high glucose concentrations and release insulin or other antidiabetic agents accordingly.
Correct answer is: Diabetes mellitus
Q.93 Which of the following is a common reason to select an injectable depot formulation over an oral tablet for a drug with poor oral bioavailability?
To avoid first‑pass metabolism
To increase the drug’s taste acceptability
To enable rapid drug clearance
To reduce manufacturing costs
Explanation - Injectable depots bypass the gastrointestinal tract and hepatic first‑pass effect, improving systemic availability for drugs with poor oral absorption.
Correct answer is: To avoid first‑pass metabolism
Q.94 The primary advantage of using a biodegradable polymer over a non‑degradable polymer in an implantable sustained‑release device is:
Higher mechanical strength
Ability to be removed surgically
Elimination of the need for surgical removal after drug depletion
Lower manufacturing cost
Explanation - Biodegradable polymers degrade into biocompatible by‑products, removing the necessity for a second surgery.
Correct answer is: Elimination of the need for surgical removal after drug depletion
Q.95 Which of the following describes the effect of adding a plasticizer to a polymeric film intended for drug delivery?
Increases Tg and makes the film more brittle
Decreases Tg, enhancing flexibility and potentially increasing drug diffusion
Causes the polymer to become water‑insoluble
Prevents any drug release
Explanation - Plasticizers lower the glass transition temperature, making the polymer more flexible and often facilitating drug diffusion.
Correct answer is: Decreases Tg, enhancing flexibility and potentially increasing drug diffusion
Q.96 In a controlled‑release tablet, a ‘hydrophilic matrix’ typically utilizes which of the following polymers?
Polyethylene (PE)
Hydroxypropyl methylcellulose (HPMC)
Polystyrene (PS)
Polyvinylidene fluoride (PVDF)
Explanation - HPMC is a widely used hydrophilic polymer that swells to form a gel barrier governing drug release.
Correct answer is: Hydroxypropyl methylcellulose (HPMC)
Q.97 Which of the following mechanisms is most likely to dominate drug release from a highly porous, non‑degradable matrix?
Polymer erosion
Diffusion through interconnected pores
Swelling of the matrix
Chemical reaction with the drug
Explanation - In a porous, stable matrix, the drug diffuses through the network of pores, as the matrix itself does not degrade or swell significantly.
Correct answer is: Diffusion through interconnected pores
Q.98 A controlled‑release system that utilizes a semi‑permeable membrane, water influx, and a piston-like drug chamber is known as:
Osmotic pump
Matrix tablet
Enteric coating
Ion‑exchange resin
Explanation - The described architecture matches an osmotic pump where water entry creates pressure that pushes drug out through an orifice.
Correct answer is: Osmotic pump
Q.99 When designing a sustained‑release formulation for a drug with a narrow therapeutic window, the most critical design goal is to:
Maximize the initial burst release
Maintain plasma concentrations within the therapeutic range for the entire dosing interval
Achieve the fastest possible drug release
Use the cheapest possible polymer
Explanation - Drugs with narrow therapeutic windows require precise control to avoid sub‑therapeutic or toxic levels.
Correct answer is: Maintain plasma concentrations within the therapeutic range for the entire dosing interval
Q.100 Which of the following is a primary cause for variability in drug release from a batch of polymeric microspheres?
Uniform particle size distribution
Consistent polymer composition
Variations in solvent evaporation rate during fabrication
Use of a single drug
Explanation - Inconsistent solvent removal can lead to differences in polymer porosity and drug distribution, causing batch‑to‑batch variability.
Correct answer is: Variations in solvent evaporation rate during fabrication
Q.101 A drug‑delivery system that employs a polymer that swells in response to increased temperature is called:
Thermo‑responsive system
pH‑responsive system
Magnetically‑responsive system
Enzyme‑responsive system
Explanation - Thermo‑responsive polymers change their swelling behavior with temperature, modulating drug release.
Correct answer is: Thermo‑responsive system
Q.102 Which of the following techniques is most commonly used to produce nanofibrous mats for drug delivery via electrospinning?
Melt extrusion
Solvent‑casting
Electrospinning
Freeze‑drying
Explanation - Electrospinning creates continuous nanofibers with high surface‑area‑to‑volume ratios, suitable for controlled drug release.
Correct answer is: Electrospinning
Q.103 In a drug‑eluting stent, what is the main purpose of incorporating a drug like sirolimus?
To prevent blood clot formation
To inhibit smooth muscle cell proliferation and reduce restenosis
To increase stent flexibility
To improve the radiopacity of the stent
Explanation - Sirolimus (rapamycin) suppresses neointimal hyperplasia, minimizing restenosis after stent placement.
Correct answer is: To inhibit smooth muscle cell proliferation and reduce restenosis
Q.104 Which of the following best describes a ‘zero‑order release’ profile?
Release rate decreases exponentially over time
Constant amount of drug released per unit time
Release rate proportional to remaining drug amount
Release occurs only after a lag period
Explanation - Zero‑order kinetics provide a steady, time‑independent release rate, ideal for maintaining constant plasma levels.
Correct answer is: Constant amount of drug released per unit time
Q.105 In a sustained‑release tablet, the presence of a hydrophobic polymer like ethylcellulose primarily serves to:
Increase tablet hardness
Create a barrier to slow drug diffusion
Improve tablet taste
Accelerate drug release
Explanation - Hydrophobic polymers form low‑permeability layers that restrict drug movement, extending release duration.
Correct answer is: Create a barrier to slow drug diffusion
Q.106 When evaluating an in‑vitro release study, which of the following graphical representations best identifies a Higuchi kinetic profile?
Cumulative % released vs. time (linear)
Cumulative amount released vs. square root of time (linear)
Log cumulative remaining vs. time (linear)
Cumulative amount released vs. time (linear)
Explanation - The Higuchi model predicts that the amount of drug released is proportional to the square root of time, giving a straight line on such a plot.
Correct answer is: Cumulative amount released vs. square root of time (linear)
Q.107 A drug‑delivery system that utilizes ion‑exchange resins releases the drug primarily by:
Diffusion through polymer pores
Exchange of drug ions with counter‑ions in the surrounding fluid
Polymer erosion
Swelling of the resin matrix
Explanation - Ion‑exchange resins release the drug when ions in the surrounding medium replace the drug ions bound to the resin.
Correct answer is: Exchange of drug ions with counter‑ions in the surrounding fluid
Q.108 Which of the following polymers is considered non‑biodegradable and often used as a rate‑controlling membrane in implantable devices?
Polylactic acid (PLA)
Poly(lactic‑co‑glycolic acid) (PLGA)
Polyethylene terephthalate (PET)
Polycaprolactone (PCL)
Explanation - PET is a stable, non‑degradable polymer frequently employed as a diffusion barrier in medical implants.
Correct answer is: Polyethylene terephthalate (PET)
Q.109 A sustained‑release system that releases drug through a biodegradable polymer that erodes from the surface is exhibiting:
Bulk erosion
Surface erosion
Swelling‑controlled release
Osmotic pumping
Explanation - Surface erosion removes material layer by layer from the exterior, controlling the release rate.
Correct answer is: Surface erosion
Q.110 Which of the following best explains why a high‑loading drug‑polymer system might experience a higher initial burst release?
The polymer becomes more hydrophobic
More drug is located near the surface or in interconnected pores
The polymer’s Tg increases
The device becomes electrically conductive
Explanation - Higher drug loading often leads to drug residing close to the surface or creating larger pores, facilitating a rapid initial release.
Correct answer is: More drug is located near the surface or in interconnected pores
Q.111 Which of the following statements about the Korsmeyer‑Peppas model is correct?
It is only applicable to zero‑order release systems
The exponent n indicates the mechanism of drug release
It assumes polymer degradation is the sole release mechanism
It is used exclusively for liquid formulations
Explanation - In the Korsmeyer‑Peppas equation, the value of n helps differentiate between Fickian diffusion, anomalous transport, or case‑II transport.
Correct answer is: The exponent n indicates the mechanism of drug release
Q.112 A drug‑delivery implant that releases drug via a combination of diffusion and polymer degradation is best described as:
Purely diffusion‑controlled
Purely erosion‑controlled
Mixed (diffusion‑erosion) controlled
Osmotically controlled
Explanation - When both diffusion through the polymer and degradation of the matrix contribute to release, the system is considered mixed‑controlled.
Correct answer is: Mixed (diffusion‑erosion) controlled
Q.113 In a transdermal patch, the term “flux” refers to:
The total amount of drug in the patch
The rate of drug permeation per unit area per unit time
The mechanical strength of the patch
The electrical conductivity of the patch
Explanation - Flux (J) quantifies how much drug passes through a given area of skin per unit time, typically expressed in µg/cm²·h.
Correct answer is: The rate of drug permeation per unit area per unit time
Q.114 Which of the following is a common method to increase the residence time of a drug‑delivery system in the nasal cavity?
Using a high‑density polymer
Incorporating mucoadhesive polymers like chitosan
Adding a surfactant to reduce surface tension
Making the formulation highly volatile
Explanation - Mucoadhesive agents bind to nasal mucosa, extending the contact time and enhancing drug absorption.
Correct answer is: Incorporating mucoadhesive polymers like chitosan
Q.115 A major challenge when formulating a sustained‑release ocular insert is:
Achieving sufficient mechanical strength for insertion
Ensuring rapid drug release within minutes
Preventing any interaction with tear fluid
Maintaining opacity of the insert
Explanation - The insert must be strong enough to handle insertion yet flexible enough to conform to ocular structures without causing irritation.
Correct answer is: Achieving sufficient mechanical strength for insertion
Q.116 Which of the following is a typical characteristic of a biodegradable polymer used for a subcutaneous depot injection?
Very high glass transition temperature (>150 °C)
Rapid dissolution in water within minutes
Controlled hydrolytic degradation over weeks to months
Electrical conductivity
Explanation - Depot injections require polymers that degrade at a predictable rate to sustain drug release over the intended period.
Correct answer is: Controlled hydrolytic degradation over weeks to months
Q.117 In a matrix tablet, increasing the proportion of a water‑soluble polymer (e.g., hydroxypropyl methylcellulose) relative to a hydrophobic polymer will generally:
Increase the burst effect
Decrease the overall drug release rate
Make the tablet more brittle
Prevent any drug release
Explanation - Higher amounts of a water‑soluble polymer promote faster water uptake and drug diffusion, often leading to a larger initial burst.
Correct answer is: Increase the burst effect
Q.118 Which of the following factors most directly influences the rate of drug diffusion through a polymeric membrane?
Polymer’s dielectric constant
Polymer’s permeability coefficient
Device’s external shape
Manufacturing country
Explanation - The permeability coefficient (P) combines diffusion and partition coefficients, directly governing the drug flux through the membrane.
Correct answer is: Polymer’s permeability coefficient
Q.119 A controlled‑release system that delivers a drug in response to an external magnetic field is classified as:
Thermo‑responsive
Magnetically‑responsive
pH‑responsive
Enzyme‑responsive
Explanation - Magnetically‑responsive systems use magnetic fields to trigger or modulate drug release, often via magnetic nanoparticles.
Correct answer is: Magnetically‑responsive
Q.120 In the context of drug delivery, the term “chronotherapy” refers to:
Delivering drugs at specific times to align with circadian rhythms
Using drugs that degrade quickly
Administering drugs only during night time
Providing instant release formulations
Explanation - Chronotherapy optimizes therapeutic outcomes by timing drug release to coincide with biological cycles.
Correct answer is: Delivering drugs at specific times to align with circadian rhythms
Q.121 Which of the following is the most likely reason to incorporate a high‑glass‑transition‑temperature polymer in a transdermal patch?
To ensure the patch remains flexible at skin temperature
To increase the rate of drug diffusion
To prevent the patch from becoming too soft and losing structural integrity
To promote rapid drug degradation
Explanation - A high Tg polymer remains rigid at skin temperature, maintaining patch shape and controlling drug release.
Correct answer is: To prevent the patch from becoming too soft and losing structural integrity
Q.122 Which of the following best explains why a drug with low water solubility may be formulated as a solid lipid nanoparticle for sustained release?
Lipid nanoparticles increase the drug’s aqueous solubility and allow controlled release as the lipid matrix slowly degrades
Solid lipid nanoparticles instantly dissolve in the gastrointestinal tract
They provide a taste‑masking effect
They prevent any interaction with the body’s enzymes
Explanation - Solid lipid nanoparticles encapsulate poorly soluble drugs, improving apparent solubility and providing a sustained release matrix.
Correct answer is: Lipid nanoparticles increase the drug’s aqueous solubility and allow controlled release as the lipid matrix slowly degrades
Q.123 When a controlled‑release tablet is stored under high humidity, the most probable effect on drug release is:
Decrease in release rate due to polymer hardening
Increase in release rate because of premature polymer swelling
No change in release profile
Complete loss of drug activity
Explanation - Moisture can cause premature swelling of hydrophilic polymers, accelerating drug diffusion.
Correct answer is: Increase in release rate because of premature polymer swelling
Q.124 A polymer that exhibits a rapid initial swelling followed by a slower, sustained swelling is described as:
Biphasic swelling
Zero‑order swelling
First‑order swelling
Non‑swelling
Explanation - Biphasic swelling involves an early fast swelling phase and a later slower phase, influencing drug release kinetics.
Correct answer is: Biphasic swelling
Q.125 Which of the following analytical techniques can directly assess the porosity of a polymeric scaffold used for sustained drug release?
Scanning electron microscopy (SEM)
Nuclear magnetic resonance (NMR)
Mass spectrometry (MS)
Ultraviolet‑visible spectroscopy (UV‑Vis)
Explanation - SEM provides high‑resolution images of scaffold architecture, allowing qualitative and quantitative porosity analysis.
Correct answer is: Scanning electron microscopy (SEM)
Q.126 In a matrix tablet, the use of a polymer that undergoes a glass transition near body temperature can lead to:
Increased brittleness at physiological temperature
Enhanced drug diffusion due to polymer softening
Complete inhibition of drug release
Immediate tablet disintegration
Explanation - When the polymer softens near body temperature, its chains become more mobile, facilitating drug diffusion.
Correct answer is: Enhanced drug diffusion due to polymer softening
Q.127 Which of the following best describes the primary advantage of using a biodegradable polymer for intravitreal drug delivery?
Provides instant visual improvement
Eliminates the need for repeated intravitreal injections
Allows the drug to cross the blood‑retina barrier
Makes the device visible on MRI
Explanation - Biodegradable intravitreal implants release drug over months, reducing the frequency of invasive injections.
Correct answer is: Eliminates the need for repeated intravitreal injections
Q.128 The primary reason for incorporating a “sealant” layer in a reservoir-type implant is to:
Enhance drug solubility
Prevent premature drug leakage before implantation
Increase mechanical strength
Provide a site for tissue integration
Explanation - A sealant ensures the drug remains contained during handling and storage, releasing only through the designed membrane after implantation.
Correct answer is: Prevent premature drug leakage before implantation
Q.129 When a drug‑delivery system is described as having “pulsatile release,” the intended therapeutic goal is to:
Maintain a constant plasma concentration
Deliver the drug in timed bursts matching physiological needs
Provide immediate relief only
Avoid any drug release for the first month
Explanation - Pulsatile systems release drug at specific intervals to align with circadian or disease‑related rhythms.
Correct answer is: Deliver the drug in timed bursts matching physiological needs
Q.130 Which of the following is a typical method for achieving a prolonged lag time in an oral controlled‑release tablet?
Coating with a highly soluble polymer
Incorporating a high‑density filler
Applying an enteric coating that dissolves at higher pH
Using a highly porous matrix
Explanation - Enteric coatings prevent drug release in the acidic stomach and dissolve later in the intestine, creating a lag period.
Correct answer is: Applying an enteric coating that dissolves at higher pH
Q.131 A drug‑delivery device that utilizes a polymer that degrades via enzymatic cleavage is most suitable for:
Targeted release in enzyme‑rich environments like tumor tissue
Rapid release in the bloodstream
Release only under high temperature
Release in the presence of magnetic fields
Explanation - Enzyme‑responsive polymers degrade preferentially where specific enzymes are overexpressed, providing site‑specific delivery.
Correct answer is: Targeted release in enzyme‑rich environments like tumor tissue
Q.132 Which of the following is a primary factor that determines the diffusion path length in a spherical matrix tablet?
Tablet radius
Drug’s color
Manufacturing facility location
Packaging material
Explanation - The diffusion path length is directly related to the distance from the tablet’s surface to its center, which is a function of radius.
Correct answer is: Tablet radius
Q.133 In a drug‑eluting stent, the term “elution half‑life” refers to:
The time required for half of the drug to be released from the stent
The time taken for the stent to dissolve completely
The period before the stent expands to full size
The time required for half of the polymer to degrade
Explanation - Elution half‑life is a measure of the rate at which the drug is released from the stent coating.
Correct answer is: The time required for half of the drug to be released from the stent
Q.134 Which of the following best describes a “hydrogel” used in controlled‑release applications?
A non‑absorbing, rigid polymer
A water‑swollen, cross‑linked polymer network
A metal alloy used for implants
A crystalline powder
Explanation - Hydrogels absorb large amounts of water, forming a gel that can control drug diffusion.
Correct answer is: A water‑swollen, cross‑linked polymer network