Q.1 Which physicochemical property most directly influences a drug's ability to cross the blood‑brain barrier?
Molecular weight
pKa
LogP (octanol/water partition coefficient)
Melting point
Explanation - A moderate LogP (≈2‑4) indicates sufficient lipophilicity for passive diffusion across the highly selective blood‑brain barrier.
Correct answer is: LogP (octanol/water partition coefficient)
Q.2 In electro‑responsive drug delivery, what is the primary role of a conductive polymer coating on a reservoir device?
Increase mechanical strength
Provide a barrier to water uptake
Modulate drug release upon applied voltage
Enhance biocompatibility
Explanation - Conductive polymers change their oxidation state under an applied voltage, altering their swelling or pore size and thereby controlling drug release.
Correct answer is: Modulate drug release upon applied voltage
Q.3 Which of the following best describes the Nernst‑Planck equation in the context of ion‑driven drug release?
Relates diffusion coefficient to temperature
Describes flux of charged species under concentration and electric potential gradients
Calculates the dielectric constant of a polymer matrix
Predicts the dissolution rate of a solid drug
Explanation - The Nernst‑Planck equation combines diffusion and migration terms to model ion transport in response to concentration and electric field gradients.
Correct answer is: Describes flux of charged species under concentration and electric potential gradients
Q.4 What is the most common method to assess the stability of a protein‑based drug within an implanted electronic device?
Differential Scanning Calorimetry (DSC)
Fourier‑Transform Infrared Spectroscopy (FTIR)
Circular Dichroism (CD) spectroscopy
X‑ray Diffraction (XRD)
Explanation - CD spectroscopy monitors secondary structure changes in proteins, providing direct information on conformational stability under device conditions.
Correct answer is: Circular Dichroism (CD) spectroscopy
Q.5 Which factor primarily determines the rate of drug diffusion through a hydrogel matrix?
Hydrogel cross‑link density
Electrical conductivity of the hydrogel
Color of the hydrogel
Magnetic susceptibility
Explanation - Higher cross‑link density reduces mesh size, hindering diffusion and slowing drug release.
Correct answer is: Hydrogel cross‑link density
Q.6 A drug delivery microchip utilizes a field‑effect transistor (FET) to control release. What parameter of the FET is typically modulated to open the drug reservoir?
Gate voltage
Drain current
Source‑to‑drain resistance
Threshold frequency
Explanation - Changing the gate voltage alters the conductivity of the channel, which can be used to open or close microvalves for drug release.
Correct answer is: Gate voltage
Q.7 Which of the following is a key biological consideration when designing a transdermal drug delivery system for a peptide drug?
Skin lipid composition
Blood pH
Gastrointestinal enzyme activity
Renal clearance rate
Explanation - Peptide drugs face the barrier of the stratum corneum; the lipid matrix governs permeability and must be considered for formulation.
Correct answer is: Skin lipid composition
Q.8 What does the term 'Zeta potential' describe in the context of nanoparticle drug carriers?
Electrical charge at the particle surface influencing colloidal stability
Magnetic moment of the particle
Particle size distribution
Thermal conductivity of the carrier
Explanation - Zeta potential quantifies surface charge; high magnitude (±) values prevent aggregation, crucial for stable suspensions.
Correct answer is: Electrical charge at the particle surface influencing colloidal stability
Q.9 In a pH‑responsive drug delivery system, which chemical group is most commonly used to impart acid‑sensitivity?
Ester
Amide
Hydrazone
Carbamate
Explanation - Hydrazone linkages cleave under acidic conditions, enabling drug release in low‑pH environments like tumor tissue.
Correct answer is: Hydrazone
Q.10 Which measurement technique is most suitable for determining the dielectric constant of a polymer matrix used in an implantable drug reservoir?
Impedance spectroscopy
Thermogravimetric analysis (TGA)
Nuclear magnetic resonance (NMR)
High‑performance liquid chromatography (HPLC)
Explanation - Impedance spectroscopy directly measures the frequency‑dependent electrical response, yielding dielectric constant values.
Correct answer is: Impedance spectroscopy
Q.11 Which physicochemical characteristic most strongly influences the renal clearance of a small molecule drug?
Molecular weight
Hydrogen‑bond donors
LogD at pH 7.4
Vapor pressure
Explanation - Compounds below ~30–50 kDa are freely filtered; higher molecular weight reduces renal clearance.
Correct answer is: Molecular weight
Q.12 A micro‑needle array for drug delivery is fabricated from silicon. Which property of silicon is most critical for ensuring painless insertion?
Young's modulus
Thermal conductivity
Electrical resistivity
Optical transparency
Explanation - A high Young's modulus provides the stiffness needed for the needles to penetrate the skin without buckling, reducing pain.
Correct answer is: Young's modulus
Q.13 What is the primary advantage of using a biphasic (hydrophilic‑hydrophobic) polymer blend in a drug depot?
Improved mechanical strength
Controlled biphasic release (initial burst then sustained)
Enhanced electrical conductivity
Increased optical clarity
Explanation - The hydrophilic phase releases drug quickly while the hydrophobic phase provides a prolonged release, achieving biphasic kinetics.
Correct answer is: Controlled biphasic release (initial burst then sustained)
Q.14 In a bio‑electronic implant delivering insulin, which biological factor must be monitored to avoid hypoglycemia?
Blood glucose concentration
Serum creatinine level
Heart rate variability
Body temperature
Explanation - Real‑time glucose monitoring ensures insulin dosing is matched to the patient's metabolic state, preventing low blood sugar.
Correct answer is: Blood glucose concentration
Q.15 Which equation is used to predict the diffusion coefficient of a drug molecule in a polymer matrix based on its size and temperature?
Stokes‑Einstein equation
Arrhenius equation
Fick's first law
Nernst equation
Explanation - The Stokes‑Einstein relation links diffusion coefficient to temperature, viscosity, and hydrodynamic radius of the molecule.
Correct answer is: Stokes‑Einstein equation
Q.16 Which type of electrical stimulation is most commonly used to trigger drug release from an ion‑exchange membrane?
Direct current (DC) pulse
Alternating current (AC) at 60 Hz
Radiofrequency (RF) heating
Ultrasound waves
Explanation - A DC pulse creates a steady electric field that drives ions through the ion‑exchange membrane, releasing the drug.
Correct answer is: Direct current (DC) pulse
Q.17 When designing a nanocarrier for oral delivery, which physicochemical barrier is most problematic?
Stomach acidity
Intestinal mucus layer
Blood‑brain barrier
Pulmonary surfactant
Explanation - Low pH in the stomach can degrade many drug molecules and destabilize nanocarriers, reducing bioavailability.
Correct answer is: Stomach acidity
Q.18 What does the term 'burst release' refer to in drug delivery systems?
A rapid initial release of drug followed by slower release
Release triggered only by temperature increase
Continuous steady‑state release over months
Release that occurs only after enzymatic activation
Explanation - Burst release is an initial spike in drug concentration due to surface‑bound drug or rapid diffusion before the system reaches a controlled phase.
Correct answer is: A rapid initial release of drug followed by slower release
Q.19 Which property of a drug molecule influences its partitioning into a lipid membrane most strongly?
Hydrogen‑bond donor count
LogP
Molecular weight
Melting point
Explanation - LogP quantifies lipophilicity; higher values favor partitioning into lipid bilayers.
Correct answer is: LogP
Q.20 In a controlled‑release polymeric implant, what is the effect of increasing the polymer's glass transition temperature (Tg)?
Accelerates drug diffusion
Reduces polymer swelling at body temperature
Increases electrical conductivity
Improves optical transparency
Explanation - A higher Tg means the polymer remains in a glassy, less mobile state at 37 °C, limiting swelling and slowing drug diffusion.
Correct answer is: Reduces polymer swelling at body temperature
Q.21 Which analytical technique is most appropriate for quantifying a drug released from an electrochemical reservoir in real time?
Cyclic voltammetry
UV‑Vis spectrophotometry
Mass spectrometry
Atomic force microscopy
Explanation - Cyclic voltammetry measures current changes associated with drug oxidation/reduction, providing real‑time release data.
Correct answer is: Cyclic voltammetry
Q.22 What is the main advantage of using a biodegradable polymer (e.g., PLGA) for an implanted drug depot?
Infinite drug loading capacity
Elimination of surgical removal after drug depletion
Improved electrical conductivity
Resistance to enzymatic degradation
Explanation - Biodegradable polymers gradually break down into biocompatible by‑products, removing the need for a second surgery.
Correct answer is: Elimination of surgical removal after drug depletion
Q.23 Which biological factor can cause premature drug release from a pH‑sensitive liposome administered intravenously?
Serum protein adsorption (opsonization)
High blood pressure
Low oxygen tension
Elevated body temperature
Explanation - Proteins bind to the liposome surface, destabilizing the pH‑sensitive membrane and triggering premature release.
Correct answer is: Serum protein adsorption (opsonization)
Q.24 In an iontophoresis drug delivery device, which parameter governs the magnitude of electro‑osmotic flow?
Surface charge of the skin
Applied current density
Device temperature
Drug solubility
Explanation - Higher current density increases electro‑osmotic solvent movement, enhancing drug transport through the skin.
Correct answer is: Applied current density
Q.25 Which physicochemical property of a drug is most critical for its stability during microwave‑assisted synthesis of a polymeric carrier?
Thermal stability
Magnetic susceptibility
Dielectric constant
pKa
Explanation - Microwave heating raises temperature rapidly; a drug must withstand the thermal exposure without degradation.
Correct answer is: Thermal stability
Q.26 What does the term 'bio‑fouling' refer to in the context of implantable drug delivery devices?
Accumulation of cells and proteins on device surfaces
Electrochemical corrosion of metal parts
Degradation of polymer matrix by UV light
Formation of gas bubbles in the device
Explanation - Bio‑fouling can block micro‑valves or alter release kinetics, compromising device performance.
Correct answer is: Accumulation of cells and proteins on device surfaces
Q.27 Which of the following is a common method to increase the solubility of a poorly water‑soluble drug in a nanoemulsion?
Using a high‑logP co‑solvent
Increasing the surfactant concentration
Adding a strong acid
Cooling the formulation
Explanation - Surfactants lower interfacial tension, stabilizing droplets and enhancing drug solubilization.
Correct answer is: Increasing the surfactant concentration
Q.28 Which electrical parameter is most directly linked to Joule heating in an implanted drug release heater?
Voltage
Current
Resistance
Capacitance
Explanation - Joule heating follows P = I²R; the current through the resistive element determines heat generation.
Correct answer is: Current
Q.29 In a magnetically guided drug delivery system, what is the main physicochemical property of the carrier that determines magnetic responsiveness?
Magnetic susceptibility
Electrical conductivity
Hydrophobicity
Surface charge
Explanation - High magnetic susceptibility (e.g., iron oxide nanoparticles) enables the carrier to be directed by external magnetic fields.
Correct answer is: Magnetic susceptibility
Q.30 Which physiological barrier is primarily responsible for limiting the oral absorption of macromolecular drugs?
Gastric emptying time
Intestinal epithelial tight junctions
Renal filtration rate
Pulmonary alveolar barrier
Explanation - Tight junctions restrict paracellular transport of large molecules, hindering their uptake.
Correct answer is: Intestinal epithelial tight junctions
Q.31 The term 'critical micelle concentration (CMC)' is most relevant to which type of drug delivery system?
Liposomes
Polymeric nanoparticles
Micelles
Implantable rods
Explanation - CMC is the concentration above which amphiphilic molecules self‑assemble into micelles, encapsulating hydrophobic drugs.
Correct answer is: Micelles
Q.32 When an electrochemical drug reservoir uses a gold electrode, what is a key advantage of gold compared to copper?
Higher electrical resistivity
Greater biocompatibility and corrosion resistance
Lower cost
Higher thermal conductivity
Explanation - Gold is inert in physiological environments, reducing risk of metal ion release and tissue irritation.
Correct answer is: Greater biocompatibility and corrosion resistance
Q.33 Which of the following best explains why a high dielectric constant polymer is chosen for an electrically triggered drug release system?
It stores more electric charge, enabling stronger electric fields across the matrix
It enhances the mechanical strength of the device
It improves optical clarity for visual monitoring
It reduces the device's overall mass
Explanation - A high dielectric constant increases capacitance, allowing efficient charge storage and field generation to drive release.
Correct answer is: It stores more electric charge, enabling stronger electric fields across the matrix
Q.34 In a glucose‑responsive insulin delivery system using phenylboronic acid, which physicochemical interaction is essential for glucose sensing?
Reversible covalent bonding between glucose and phenylboronic acid
Hydrophobic interaction between glucose and polymer matrix
Electrostatic attraction of glucose to charged groups
Van der Waals forces
Explanation - Phenylboronic acid forms reversible cyclic esters with diols (glucose), causing polymer swelling and insulin release.
Correct answer is: Reversible covalent bonding between glucose and phenylboronic acid
Q.35 Which factor most strongly influences the rate of drug permeation through a polymeric membrane in a diffusion‑controlled system?
Membrane thickness
Electrical conductivity of the drug
Magnetic field strength
Color of the polymer
Explanation - According to Fick’s law, flux is inversely proportional to membrane thickness; thinner membranes increase permeation rate.
Correct answer is: Membrane thickness
Q.36 A drug‑loaded nanofiber scaffold shows a rapid decrease in release rate after the first 24 h. Which phenomenon most likely explains this observation?
Formation of a diffusion barrier due to polymer swelling
Burst release of surface‑bound drug followed by diffusion‑limited release
Enzymatic degradation of the nanofibers
Temperature increase in the surrounding medium
Explanation - Initial burst releases drug near the surface; thereafter, only drug within fibers diffuses out more slowly.
Correct answer is: Burst release of surface‑bound drug followed by diffusion‑limited release
Q.37 Which property of a drug molecule determines its ability to be encapsulated efficiently within a PLGA nanoparticle?
Hydrophobicity
Molecular polarity
Melting point
Vapor pressure
Explanation - PLGA is hydrophobic; drugs with higher LogP partition more readily into the polymer matrix.
Correct answer is: Hydrophobicity
Q.38 In an implantable drug delivery device, why is it important to match the device's mechanical modulus to surrounding tissue?
To avoid mechanical irritation and inflammation
To increase electrical conductivity
To enhance drug solubility
To improve optical visibility
Explanation - A modulus mismatch can cause stress concentrations, leading to tissue damage and foreign‑body response.
Correct answer is: To avoid mechanical irritation and inflammation
Q.39 Which of the following is a primary safety concern when delivering drugs using an electrically actuated micro‑valve?
Electrolysis of water producing gas bubbles
Generation of magnetic fields
Increase in device opacity
Formation of crystalline drug deposits
Explanation - Electrolysis can generate H₂ and O₂, leading to pressure buildup and possible device failure.
Correct answer is: Electrolysis of water producing gas bubbles
Q.40 Which biological factor is most likely to alter the release profile of a drug from an injectable hydrogel in an inflamed tissue site?
Elevated enzymatic activity
Lower body temperature
Reduced blood flow
Increased melanin concentration
Explanation - Inflammation often up‑regulates proteases that degrade hydrogel networks, accelerating drug release.
Correct answer is: Elevated enzymatic activity
Q.41 What is the main advantage of using a pulsatile drug delivery system for chronotherapy?
Provides drug doses aligned with circadian rhythms
Eliminates the need for any pharmacokinetic modeling
Ensures constant plasma concentration
Reduces manufacturing cost
Explanation - Pulsatile release can be timed to coincide with disease activity peaks, improving therapeutic efficacy.
Correct answer is: Provides drug doses aligned with circadian rhythms
Q.42 In a microfluidic drug synthesis chip, why is laminar flow preferred over turbulent flow?
It allows precise control over mixing and reaction times
It increases the electrical conductivity of the fluid
It reduces the need for temperature control
It enhances the magnetic properties of the product
Explanation - Laminar flow yields predictable, diffusion‑limited mixing, essential for reproducible drug synthesis on chip.
Correct answer is: It allows precise control over mixing and reaction times
Q.43 Which analytical method would you use to determine the size distribution of lipid nanoparticles intended for transdermal delivery?
Dynamic light scattering (DLS)
Gas chromatography (GC)
Fourier‑transform infrared spectroscopy (FTIR)
Electrochemical impedance spectroscopy (EIS)
Explanation - DLS measures Brownian motion of particles to calculate hydrodynamic diameter and size distribution.
Correct answer is: Dynamic light scattering (DLS)
Q.44 A drug carrier is designed to release its payload when the local pH drops from 7.4 to 6.5. Which type of chemical bond is most suitable for this trigger?
Acetal linkage
Amide bond
Ester bond
Disulfide bond
Explanation - Acetals are stable at neutral pH but hydrolyze under mildly acidic conditions, providing pH‑triggered release.
Correct answer is: Acetal linkage
Q.45 In a bio‑electronic patch delivering analgesic drug via iontophoresis, why is the anode placed over the drug reservoir?
Negatively charged drug ions are repelled from the anode, driving them into the skin
Anode generates heat to increase drug solubility
Anode creates a magnetic field that guides the drug
Anode reduces the drug’s pKa
Explanation - Iontophoresis uses electric repulsion; placing the anode over a negatively charged drug pushes it toward the cathode through skin.
Correct answer is: Negatively charged drug ions are repelled from the anode, driving them into the skin
Q.46 Which factor is most important when selecting a polymer for an implantable device that must function for several years without degradation?
Biostability and resistance to hydrolysis
Low glass transition temperature
High water absorption
Strong fluorescence
Explanation - Long‑term implants require polymers that do not degrade or lose mechanical integrity in the physiological environment.
Correct answer is: Biostability and resistance to hydrolysis
Q.47 What is the purpose of adding polyethylene glycol (PEG) to the surface of nanoparticles used for systemic drug delivery?
To increase circulation time by reducing opsonization
To provide magnetic responsiveness
To enhance drug loading capacity
To make the particles visible under MRI
Explanation - PEG creates a hydrophilic steric barrier that prevents protein adsorption, extending blood residence time.
Correct answer is: To increase circulation time by reducing opsonization
Q.48 In a thermoresponsive hydrogel drug depot, what is the typical effect of raising the temperature above the lower critical solution temperature (LCST)?
Hydrogel collapses and expels water, releasing drug
Hydrogel becomes more porous, slowing release
Hydrogel degrades chemically
Hydrogel becomes electrically conductive
Explanation - Above LCST, polymer chains become hydrophobic, causing the gel to shrink and push out entrapped drug.
Correct answer is: Hydrogel collapses and expels water, releasing drug
Q.49 Which physiological condition is most likely to affect the performance of a magnetically guided drug delivery system targeting the heart?
Rapid blood flow causing shear forces
Low body temperature
High gastric acidity
Reduced lymphatic drainage
Explanation - Strong shear forces can dislodge magnetic carriers from the targeted region despite magnetic guidance.
Correct answer is: Rapid blood flow causing shear forces
Q.50 When designing a drug‑eluting stent, why is it important to control the drug's crystallinity within the polymer coating?
Crystallinity affects dissolution rate and thus release kinetics
Crystalline drugs improve electrical conductivity
Amorphous drugs cause metal corrosion
Crystallinity determines the stent's mechanical strength
Explanation - Higher crystallinity reduces solubility, slowing drug release; amorphous forms dissolve faster.
Correct answer is: Crystallinity affects dissolution rate and thus release kinetics
Q.51 Which physicochemical characteristic is most relevant for predicting the ability of a drug to be loaded into a mesoporous silica nanoparticle?
Molecular size relative to pore diameter
Electrical conductivity of the drug
Magnetic permeability
Optical absorption spectrum
Explanation - Drug molecules must be small enough to enter and occupy the pores; size exclusion governs loading efficiency.
Correct answer is: Molecular size relative to pore diameter
Q.52 Why is it advantageous to incorporate a redox‑active moiety into a polymeric drug carrier for cancer therapy?
Tumor microenvironments often have higher reducing agents, triggering drug release
Redox groups increase the carrier's magnetic properties
They improve the carrier's taste
They prevent the carrier from being taken up by healthy cells
Explanation - Elevated glutathione in tumors reduces disulfide bonds, causing carrier degradation and localized drug release.
Correct answer is: Tumor microenvironments often have higher reducing agents, triggering drug release
Q.53 Which of the following is a key determinant of the electrical impedance of a polymeric drug reservoir when used as a capacitive sensor?
Dielectric constant of the polymer
Color of the polymer
Molecular weight of the drug
Viscosity of the surrounding fluid
Explanation - Impedance of a capacitor depends on dielectric properties; higher dielectric constant lowers impedance for a given geometry.
Correct answer is: Dielectric constant of the polymer
Q.54 What is the primary reason for using a biodegradable polymer with a high glass transition temperature (Tg) in a temperature‑triggered drug delivery system for fever treatment?
The polymer stays glassy at normal body temperature and only softens when fever raises temperature
High Tg improves the polymer’s electrical conductivity
It makes the device visible on X‑ray
High Tg reduces the polymer’s mechanical strength
Explanation - A high Tg ensures the polymer remains rigid at 37 °C; when fever raises temperature above Tg, the matrix softens, releasing drug.
Correct answer is: The polymer stays glassy at normal body temperature and only softens when fever raises temperature
Q.55 Which property of a drug molecule is most predictive of its susceptibility to enzymatic degradation in the bloodstream?
Presence of labile ester or amide bonds
High LogP
Large molecular weight
Low melting point
Explanation - Esterases and proteases cleave ester and amide bonds, leading to rapid metabolism of susceptible drugs.
Correct answer is: Presence of labile ester or amide bonds
Q.56 In a drug‑loaded microelectromechanical system (MEMS) pump, what is the main function of the check valve?
Prevent backflow of fluid after each pump stroke
Increase the electric field strength
Generate heat to melt the drug
Provide optical feedback
Explanation - The check valve ensures unidirectional flow, maintaining precise dosing with each actuation.
Correct answer is: Prevent backflow of fluid after each pump stroke
Q.57 Which physicochemical parameter is most directly altered when a drug is encapsulated in a liposome with a cholesterol-rich membrane?
Membrane fluidity and permeability
Electrical conductivity
Magnetic susceptibility
Optical refractive index
Explanation - Cholesterol stiffens lipid bilayers, reducing fluidity and slowing drug leakage.
Correct answer is: Membrane fluidity and permeability
Q.58 When evaluating the biocompatibility of an implanted electronic drug delivery device, which in‑vitro assay is most commonly used?
MTT cytotoxicity assay
Gel electrophoresis
Gas chromatography
Atomic absorption spectroscopy
Explanation - MTT measures cell metabolic activity, indicating cytotoxic effects of device materials.
Correct answer is: MTT cytotoxicity assay
Q.59 What is the main advantage of using a micro‑needle patch over traditional hypodermic injection for vaccine delivery?
Reduced pain and needle‑phobia
Higher drug stability at room temperature
Ability to deliver larger drug volumes
Elimination of need for sterile manufacturing
Explanation - Micro‑needles penetrate only the superficial skin layers, causing minimal discomfort.
Correct answer is: Reduced pain and needle‑phobia
Q.60 Which of the following best describes the term 'pharmacokinetic half‑life'?
Time required for the plasma concentration of a drug to reduce by 50%
Time needed for the drug to reach its target tissue
Duration of drug action at the receptor site
Time required for the drug to be completely eliminated
Explanation - Half‑life is the time for the concentration to fall to half its initial value, reflecting elimination kinetics.
Correct answer is: Time required for the plasma concentration of a drug to reduce by 50%
Q.61 In a polymeric nanoparticle designed for pulmonary delivery, why is a low surface tension important?
It promotes aerosolization and deep lung deposition
It increases electrical conductivity
It improves magnetic guidance
It raises the melting point of the particle
Explanation - Low surface tension facilitates formation of fine droplets that can reach the alveolar region.
Correct answer is: It promotes aerosolization and deep lung deposition
Q.62 Which property of a conductive polymer most directly affects its ability to serve as an electro‑responsive drug release membrane?
Electrical conductivity
Optical transparency
Thermal expansion coefficient
Water solubility
Explanation - Higher conductivity enables efficient charge transfer, which drives conformational changes that modulate drug release.
Correct answer is: Electrical conductivity
Q.63 A drug delivery system uses a biodegradable polymer that hydrolyzes via ester bond cleavage. Which environmental factor accelerates this degradation?
Higher pH (basic conditions)
Lower temperature
Absence of water
Low ionic strength
Explanation - Ester hydrolysis is base‑catalyzed; alkaline environments increase the rate of polymer degradation.
Correct answer is: Higher pH (basic conditions)
Q.64 When designing a drug‑eluting contact lens, which physicochemical property of the drug is most critical to ensure sustained release?
Low water solubility
High vapor pressure
Strong fluorescence
Large molecular weight
Explanation - Poorly soluble drugs dissolve slowly from the lens matrix, providing prolonged release over time.
Correct answer is: Low water solubility
Q.65 Which measurement provides direct information on the surface charge of a colloidal drug carrier?
Zeta potential analysis
Differential scanning calorimetry
X‑ray diffraction
Raman spectroscopy
Explanation - Zeta potential quantifies the electric potential at the slipping plane of particles, indicating surface charge.
Correct answer is: Zeta potential analysis
Q.66 In an electro‑responsive drug delivery system, what is the effect of increasing the applied voltage beyond the threshold needed for release?
Potential for uncontrolled rapid release (burst)
Improved selectivity for target tissue
Reduced drug stability
Decreased device lifetime due to heating
Explanation - Excess voltage can cause over‑swelling or rupture of the polymer matrix, leading to a burst release.
Correct answer is: Potential for uncontrolled rapid release (burst)
Q.67 Which biological phenomenon can lead to the rapid clearance of nanoparticles from systemic circulation?
Opsonization by plasma proteins
Increased blood pH
Reduced heart rate
Higher body temperature
Explanation - Protein adsorption tags nanoparticles for uptake by the mononuclear phagocyte system, shortening circulation time.
Correct answer is: Opsonization by plasma proteins
Q.68 A drug delivery patch uses a temperature‑sensitive polymer that becomes permeable above 40 °C. Which clinical condition could unintentionally trigger drug release?
Fever
Hypotension
Bradycardia
Hyperglycemia
Explanation - Fever raises body temperature above the polymer’s transition point, causing unintended drug release.
Correct answer is: Fever
Q.69 Which physicochemical characteristic of a drug influences its propensity to cause irritation at the site of implantation?
pKa close to physiological pH
High molecular weight
Low LogP
Strong acidic or basic nature
Explanation - Drugs with pKa far from 7.4 can alter local pH, leading to tissue irritation.
Correct answer is: Strong acidic or basic nature
Q.70 Why is it important to control the crystallinity of a polymeric matrix used in a drug‑eluting stent?
Crystallinity determines drug diffusion rates
Crystalline polymers are electrically conductive
Amorphous polymers are magnetic
Crystallinity changes the stent’s color
Explanation - Higher crystallinity reduces free volume, slowing drug diffusion; controlling it tailors release profiles.
Correct answer is: Crystallinity determines drug diffusion rates
Q.71 In a nanocarrier designed for intracellular delivery, which cellular barrier must be traversed after endocytosis for the drug to reach its target in the cytosol?
Endosomal membrane
Nuclear envelope
Mitochondrial outer membrane
Plasma membrane
Explanation - After endocytosis, carriers are trapped in endosomes; escape is required to release the drug into the cytosol.
Correct answer is: Endosomal membrane
Q.72 Which physicochemical property of a polymer influences its swelling behavior in aqueous environments?
Hydrophilicity of polymer backbone
Electrical resistivity
Magnetic susceptibility
Optical absorbance
Explanation - Hydrophilic polymers absorb water and swell, whereas hydrophobic polymers resist swelling.
Correct answer is: Hydrophilicity of polymer backbone
Q.73 What is the main reason for incorporating a pH‑sensitive polymer coating on a drug‑loaded microneedle array intended for tumor therapy?
To achieve rapid drug release in the acidic tumor microenvironment
To increase mechanical strength of microneedles
To provide optical contrast for imaging
To reduce manufacturing cost
Explanation - Tumor tissue is often acidic (pH ≈ 6.5); pH‑sensitive polymers dissolve or swell, releasing drug selectively at the tumor site.
Correct answer is: To achieve rapid drug release in the acidic tumor microenvironment
Q.74 When assessing the release kinetics of a drug from a polymeric matrix, which plot is commonly used to determine if the release follows Higuchi diffusion?
Cumulative amount released vs. square root of time
Log concentration vs. time
Concentration vs. pH
Current vs. voltage
Explanation - Higuchi model predicts a linear relationship between amount released and √t for diffusion‑controlled systems.
Correct answer is: Cumulative amount released vs. square root of time
Q.75 Which biological factor could cause the premature degradation of a peptide drug delivered via a biodegradable polymer implant?
Proteolytic enzymes present in the tissue
Low ambient temperature
High atmospheric pressure
Reduced humidity
Explanation - Proteases can cleave peptide bonds, degrading the drug before intended release.
Correct answer is: Proteolytic enzymes present in the tissue
Q.76 A drug‑loaded nanofiber scaffold is designed to release its payload when exposed to a specific frequency of ultrasound. Which physicochemical mechanism is primarily responsible for this release?
Acoustic cavitation causing polymer disruption
Thermal heating of the scaffold
Magnetic alignment of nanofibers
Electrical polarization of the drug
Explanation - Ultrasound induces cavitation bubbles that mechanically break the polymer matrix, triggering drug release.
Correct answer is: Acoustic cavitation causing polymer disruption
Q.77 Why is it important to consider the isoelectric point (pI) of a protein drug when formulating it for delivery via iontophoresis?
The net charge of the protein at physiological pH determines its direction of movement under an electric field
pI affects the protein’s magnetic properties
pI determines the protein’s optical activity
pI controls the protein’s taste
Explanation - Proteins below their pI are negatively charged and migrate toward the anode; above pI they are positive and move toward the cathode.
Correct answer is: The net charge of the protein at physiological pH determines its direction of movement under an electric field
Q.78 Which parameter is most directly affected by adding a plasticizer to a polymeric drug reservoir?
Lowered glass transition temperature (Tg)
Increased electrical conductivity
Enhanced magnetic susceptibility
Reduced optical opacity
Explanation - Plasticizers increase polymer chain mobility, reducing Tg and making the matrix more flexible.
Correct answer is: Lowered glass transition temperature (Tg)
Q.79 In a controlled‑release system where drug release follows zero‑order kinetics, what is the characteristic of the release profile?
Constant amount of drug released per unit time
Rate decreases exponentially over time
Release is proportional to the square root of time
Drug is released only after a lag phase
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.80 Which physicochemical property of a drug influences its ability to be loaded into a mesoporous silica nanoparticle by adsorption?
Hydrophobicity
Molecular weight
pKa
Boiling point
Explanation - Hydrophobic drugs interact strongly with the silanol surface via van der Waals forces, enhancing adsorption.
Correct answer is: Hydrophobicity
Q.81 A drug delivery system uses a polymer that becomes positively charged under acidic conditions. Which type of drug would be most efficiently released in an acidic tumor microenvironment?
Negatively charged (anionic) drug
Neutral drug
Positively charged (cationic) drug
Hydrophobic drug
Explanation - Electrostatic attraction between the positively charged polymer and anionic drug promotes loading; under acidic conditions, the polymer releases the drug as charge interactions weaken.
Correct answer is: Negatively charged (anionic) drug
Q.82 What is the main reason for incorporating a permeation enhancer in a transdermal patch formulation?
To increase drug flux across the stratum corneum
To reduce the patch size
To improve the patch’s adhesive properties
To change the drug’s color
Explanation - Permeation enhancers disrupt lipid packing in the outer skin layer, facilitating drug passage.
Correct answer is: To increase drug flux across the stratum corneum
Q.83 Which of the following best explains the concept of ‘bioavailability’ in drug delivery?
The proportion of administered drug that reaches systemic circulation in an active form
The total amount of drug that can be stored in a device
The rate at which a drug is metabolized
The electrical resistance of the delivery system
Explanation - Bioavailability quantifies how much of the dose becomes available at the site of action after delivery.
Correct answer is: The proportion of administered drug that reaches systemic circulation in an active form
Q.84 When a drug delivery device uses a piezoelectric actuator to generate micro‑jets of drug solution, which physicochemical property of the actuator material is essential?
High piezoelectric coefficient
Low optical absorption
High magnetic permeability
Low dielectric constant
Explanation - A high piezoelectric coefficient converts electrical energy efficiently into mechanical displacement for jet formation.
Correct answer is: High piezoelectric coefficient
Q.85 Which biological consideration is critical when delivering an immunosuppressive drug via an implanted device to prevent organ transplant rejection?
Avoiding activation of the host immune response against the device
Ensuring the drug does not alter blood pH
Maintaining high oxygen levels around the device
Preventing changes in body temperature
Explanation - Immune activation could lead to device encapsulation and failure, undermining the therapeutic goal.
Correct answer is: Avoiding activation of the host immune response against the device
Q.86 What effect does increasing the ionic strength of the release medium have on the diffusion of a charged drug from a hydrogel?
Reduces electrostatic interactions, potentially increasing diffusion rate
Increases drug solubility, decreasing diffusion
Makes the hydrogel more rigid, decreasing diffusion
No effect on diffusion
Explanation - Higher ionic strength screens charge interactions, allowing charged drug molecules to move more freely.
Correct answer is: Reduces electrostatic interactions, potentially increasing diffusion rate
Q.87 A drug delivery system is designed to release a therapeutic peptide when exposed to a specific frequency of electromagnetic radiation. Which physicochemical phenomenon is most likely exploited?
Resonant heating of metallic nanoparticles causing polymer melting
Generation of magnetic fields that pull the peptide out
Photochemical cleavage of a protective group
Acoustic cavitation
Explanation - Metal nanoparticles absorb specific EM frequencies, converting them to heat that melts a polymer matrix and releases the peptide.
Correct answer is: Resonant heating of metallic nanoparticles causing polymer melting
Q.88 In a drug‑eluting ocular implant, why is it important to match the drug's solubility with the aqueous humor environment?
Ensures consistent release without precipitation
Improves the implant’s mechanical strength
Reduces the need for electrical power
Increases the implant’s visibility on imaging
Explanation - If the drug precipitates, release becomes erratic and therapeutic levels cannot be maintained.
Correct answer is: Ensures consistent release without precipitation
Q.89 Which parameter of a micro‑pump is most directly related to its ability to deliver precise small volumes of drug?
Stroke volume control
Battery voltage
Material color
External magnetic field strength
Explanation - Accurate control of the pump’s stroke volume determines the exact amount of fluid displaced per actuation.
Correct answer is: Stroke volume control
Q.90 When a drug carrier exhibits a high positive zeta potential, what is the likely effect on its interaction with cell membranes?
Enhanced attraction to negatively charged cell surfaces
Reduced cellular uptake due to repulsion
No effect on interaction
Increased magnetic targeting
Explanation - Cell membranes are typically negatively charged; a positively charged carrier will be attracted, facilitating uptake.
Correct answer is: Enhanced attraction to negatively charged cell surfaces
Q.91 Why is the term 'first‑pass metabolism' irrelevant for an implanted subcutaneous drug delivery device?
The drug bypasses the hepatic portal system and thus avoids liver metabolism initially
Subcutaneous tissue has higher blood flow
Implanted devices do not release drug
First‑pass metabolism only occurs with oral drugs
Explanation - Subcutaneous delivery enters systemic circulation directly, circumventing the liver’s first‑pass effect.
Correct answer is: The drug bypasses the hepatic portal system and thus avoids liver metabolism initially
Q.92 Which physicochemical factor is most important for ensuring that a drug‑loaded polymeric nanoparticle can cross the blood‑brain barrier via transcytosis?
Surface functionalization with targeting ligands (e.g., transferrin)
High dielectric constant
Magnetic susceptibility
Optical fluorescence
Explanation - Ligand‑mediated transcytosis exploits receptor pathways to ferry nanoparticles across the BBB.
Correct answer is: Surface functionalization with targeting ligands (e.g., transferrin)
Q.93 In an implantable drug reservoir that uses an electrochemical reaction to generate gas and push out drug solution, which safety issue must be addressed?
Potential gas embolism from bubble formation
Loss of electrical conductivity
Change in device color
Increase in magnetic field strength
Explanation - Generated gas bubbles could enter the bloodstream, posing a risk of embolism.
Correct answer is: Potential gas embolism from bubble formation
Q.94 Which property of a drug determines its likelihood to be cleared rapidly by renal glomerular filtration?
Molecular weight below ~30 kDa
High lipophilicity (high LogP)
Strong plasma protein binding
Presence of aromatic rings
Explanation - Compounds smaller than the glomerular filtration cutoff are readily filtered and eliminated.
Correct answer is: Molecular weight below ~30 kDa
Q.95 A drug delivery system uses a polymer that degrades via hydrolysis of ester bonds. Which environmental condition would most significantly accelerate degradation?
Elevated temperature
Low humidity
Neutral pH
Absence of water
Explanation - Higher temperature increases kinetic energy, accelerating hydrolysis rates.
Correct answer is: Elevated temperature
Q.96 Which analytical technique is best suited for measuring the amount of drug released from a micro‑needle patch into skin in real time?
Microdialysis coupled with HPLC
Scanning electron microscopy
X‑ray diffraction
Thermal gravimetric analysis
Explanation - Microdialysis samples interstitial fluid continuously; HPLC quantifies drug concentration in the collected samples.
Correct answer is: Microdialysis coupled with HPLC
Q.97 Which biological factor can cause an increase in the clearance rate of a lipophilic drug administered via an implant?
Induction of hepatic cytochrome P450 enzymes
Low body temperature
Reduced blood flow to the implant site
Increased skin thickness
Explanation - Enzyme induction enhances metabolic breakdown, increasing systemic clearance of the drug.
Correct answer is: Induction of hepatic cytochrome P450 enzymes
Q.98 What is the primary purpose of adding a surfactant to a nanoparticle formulation intended for oral delivery?
To improve drug solubility and stability in the gastrointestinal tract
To increase the nanoparticle’s magnetic properties
To raise the melting point of the drug
To change the color of the formulation
Explanation - Surfactants reduce interfacial tension, stabilizing nanoparticles and enhancing drug dissolution in GI fluids.
Correct answer is: To improve drug solubility and stability in the gastrointestinal tract
Q.99 Which physicochemical property of a polymeric membrane determines its suitability for use in an osmotic pump?
Permeability to water (osmotic coefficient)
Electrical conductivity
Magnetic susceptibility
Fluorescence emission
Explanation - Osmotic pumps rely on controlled water influx through the membrane to generate pressure and drive drug release.
Correct answer is: Permeability to water (osmotic coefficient)
Q.100 In a drug‑delivery system that utilizes a temperature‑sensitive polymer with a LCST of 32 °C, what will happen when the device is placed on skin (≈33 °C)?
Polymer will collapse, expelling the drug
Polymer will become more hydrated and swell
Polymer will become electrically conductive
Polymer will change color
Explanation - Above LCST, the polymer becomes hydrophobic and contracts, forcing out the encapsulated drug.
Correct answer is: Polymer will collapse, expelling the drug
Q.101 Why is it important to consider the drug’s pKa when designing a pH‑responsive hydrogel for oral delivery?
The hydrogel’s swelling behavior can be tuned to the drug’s ionization state at gastrointestinal pH
pKa determines the drug’s taste
pKa affects the hydrogel’s magnetic properties
pKa controls the hydrogel’s color
Explanation - A drug’s ionization changes with pH; matching hydrogel responsiveness ensures optimal release where the drug is most soluble.
Correct answer is: The hydrogel’s swelling behavior can be tuned to the drug’s ionization state at gastrointestinal pH
Q.102 Which biological consideration is most relevant when delivering a chemotherapeutic agent via a biodegradable implant placed near a tumor?
Ensuring the implant does not provoke a severe inflammatory response that could promote tumor growth
Maintaining a neutral pH at the implant site
Avoiding any change in local temperature
Keeping the implant electrically neutral
Explanation - Chronic inflammation can create a microenvironment that supports tumor progression; biocompatibility is crucial.
Correct answer is: Ensuring the implant does not provoke a severe inflammatory response that could promote tumor growth
Q.103 Which physicochemical factor primarily influences the rate of drug release from a polymeric matrix via Fickian diffusion?
Diffusion coefficient of the drug in the polymer
Magnetic susceptibility of the polymer
Electrical resistance of the matrix
Optical reflectivity of the polymer
Explanation - Fick’s law shows that flux is proportional to the diffusion coefficient; higher values increase release rate.
Correct answer is: Diffusion coefficient of the drug in the polymer
Q.104 A drug‑loaded microneedle array is coated with a pH‑sensitive polymer that dissolves at pH 5.5. In which anatomical location would this coating most effectively trigger drug release?
Acidic tumor microenvironment
Neutral blood plasma
Alkaline intestinal lumen
Basic urinary tract
Explanation - Tumors often exhibit extracellular pH around 5.5‑6.5, causing the polymer to dissolve and release drug locally.
Correct answer is: Acidic tumor microenvironment
Q.105 What is the primary advantage of using a biodegradable polymer with a high degree of crystallinity for a long‑term drug depot?
Slower degradation rate, extending drug release duration
Higher electrical conductivity
Improved magnetic properties
Increased optical transparency
Explanation - Crystalline regions are less accessible to water and enzymes, slowing polymer erosion and prolonging release.
Correct answer is: Slower degradation rate, extending drug release duration
Q.106 When a drug delivery system employs a magnetic field to guide nanoparticles, which physicochemical property of the nanoparticles is most critical?
Magnetic moment (or susceptibility)
Surface charge (zeta potential)
Hydrophobicity
Fluorescence intensity
Explanation - A high magnetic moment ensures the particles respond strongly to the external magnetic field for navigation.
Correct answer is: Magnetic moment (or susceptibility)
Q.107 Which of the following best describes the concept of ‘triggered release’ in smart drug delivery systems?
Drug release is initiated by an external or internal stimulus (e.g., pH, temperature, electricity)
Drug is released continuously at a constant rate
Drug is released only when the device reaches a predetermined age
Drug release is random and uncontrolled
Explanation - Triggered release systems are engineered to respond to specific cues, enabling on‑demand dosing.
Correct answer is: Drug release is initiated by an external or internal stimulus (e.g., pH, temperature, electricity)
Q.108 In the design of an implantable electro‑responsive insulin pump, which biological parameter must be continuously monitored to avoid hypoglycemia?
Blood glucose concentration
Serum calcium level
Blood pressure
Heart rate
Explanation - Real‑time glucose monitoring allows the pump to adjust insulin delivery to maintain safe glucose levels.
Correct answer is: Blood glucose concentration
Q.109 Which physicochemical factor determines the ability of a drug to be encapsulated within a lipid‑based nanocarrier (e.g., liposome)?
Hydrophobicity of the drug
Magnetic susceptibility
Electrical conductivity
Optical refractive index
Explanation - Hydrophobic drugs preferentially partition into the lipid bilayer, enhancing encapsulation efficiency.
Correct answer is: Hydrophobicity of the drug
Q.110 A drug‑loaded polymeric scaffold exhibits a rapid initial release followed by a slower phase. Which kinetic model best describes this behavior?
Biphasic (burst + diffusion) model
Zero‑order kinetic model
First‑order kinetic model
Higuchi model only
Explanation - The observed pattern matches a biphasic release: an initial burst from surface drug, then diffusion‑controlled release.
Correct answer is: Biphasic (burst + diffusion) model
Q.111 Which of the following is a key biological challenge when delivering drugs to the posterior segment of the eye via a topical formulation?
Limited drug penetration through corneal and scleral barriers
High blood flow in the retina
Rapid metabolism by liver enzymes
Strong magnetic fields in the ocular region
Explanation - Topical drops must cross multiple ocular barriers; the posterior segment is especially difficult to reach.
Correct answer is: Limited drug penetration through corneal and scleral barriers
Q.112 Why is it important to control the particle size distribution of a nano‑emulsion intended for intravenous injection?
To avoid rapid clearance by the reticuloendothelial system and ensure uniform biodistribution
To increase the formulation's color intensity
To improve the device’s electrical conductivity
To make the formulation magnetic
Explanation - Uniform, appropriately sized nanoparticles evade rapid opsonization and provide predictable pharmacokinetics.
Correct answer is: To avoid rapid clearance by the reticuloendothelial system and ensure uniform biodistribution
Q.113 In a drug delivery system using a polymer that swells in response to a specific ion concentration, which physicochemical property of the polymer is most relevant?
Ion‑exchange capacity
Dielectric constant
Magnetic permeability
Optical absorption
Explanation - Ion‑exchange sites bind specific ions, causing osmotic swelling and triggering drug release.
Correct answer is: Ion‑exchange capacity
Q.114 Which analytical technique would be most appropriate for quantifying a small‑molecule drug released from a polymeric implant in plasma samples?
High‑performance liquid chromatography (HPLC)
Scanning electron microscopy (SEM)
Nuclear magnetic resonance (NMR)
Atomic force microscopy (AFM)
Explanation - HPLC provides sensitive, quantitative analysis of small molecules in biological fluids.
Correct answer is: High‑performance liquid chromatography (HPLC)
Q.115 When a drug‑loaded hydrogel is designed to release drug in response to increased temperature, which physicochemical change in the hydrogel drives the release?
Polymer chain collapse reducing water content
Increase in polymer crystallinity
Decrease in polymer molecular weight
Change in polymer optical properties
Explanation - Thermoresponsive polymers become hydrophobic above their transition temperature, expelling water and drug.
Correct answer is: Polymer chain collapse reducing water content
Q.116 Why is the dielectric constant of an insulating polymer important in a capacitive drug release system?
It determines the amount of stored electrical energy that can be converted into mechanical deformation for drug release
It controls the color of the polymer
It influences the magnetic field strength
It sets the polymer’s melting point
Explanation - Higher dielectric constant increases capacitance, allowing more energy to be stored and later used to actuate release mechanisms.
Correct answer is: It determines the amount of stored electrical energy that can be converted into mechanical deformation for drug release
Q.117 Which biological factor could reduce the efficacy of a drug delivered via a biodegradable polymer implant in inflamed tissue?
Elevated levels of reactive oxygen species (ROS) accelerating polymer degradation
Low body temperature
Reduced blood glucose levels
Decreased ambient light exposure
Explanation - ROS can cleave polymer bonds, causing faster degradation and premature drug release.
Correct answer is: Elevated levels of reactive oxygen species (ROS) accelerating polymer degradation
Q.118 A nanocarrier intended for targeted cancer therapy is functionalized with a folate ligand. Which biological consideration does this address?
Exploiting over‑expression of folate receptors on many cancer cells for active targeting
Increasing the nanocarrier’s magnetic properties
Changing the nanocarrier’s optical fluorescence
Reducing the nanocarrier’s size
Explanation - Folate receptors are up‑regulated on certain tumors; folate ligands enable receptor‑mediated uptake.
Correct answer is: Exploiting over‑expression of folate receptors on many cancer cells for active targeting
Q.119 In a drug delivery system using iontophoresis, which factor primarily determines the direction of drug migration?
Charge of the drug molecule relative to the electrode polarity
Molecular weight of the drug
Hydrophobicity of the drug
Color of the electrode
Explanation - Iontophoresis relies on electrostatic repulsion; positively charged drugs move away from the anode, negatively charged drugs from the cathode.
Correct answer is: Charge of the drug molecule relative to the electrode polarity
Q.120 Which physicochemical property of a drug is most directly linked to its ability to be absorbed through the intestinal epithelium via passive diffusion?
LogP (lipophilicity)
Molecular weight
Melting point
Vapor pressure
Explanation - Passive diffusion across lipid membranes favors moderately lipophilic compounds (LogP 1‑3).
Correct answer is: LogP (lipophilicity)