Dissolution testing methods MCQs With Answer

Introduction

This blog presents a focused set of multiple-choice questions (MCQs) on dissolution testing methods tailored for M.Pharm students enrolled in Advanced Biopharmaceutics & Pharmacokinetics (MPH 202T). The questions cover core concepts such as USP apparatus types, method development, sink conditions, discriminative power, sampling strategies, dissolution media selection, and data analysis including similarity factors and IVIVC relevance. Each MCQ is designed to test conceptual understanding, practical considerations and analytical reasoning required to design and validate robust dissolution methods. Use these questions for self-assessment, revision before exams, and to sharpen problem-solving skills essential in formulation development and quality control laboratories.

Q1. Which USP dissolution apparatus is most commonly used for immediate-release tablets and involves a rotating paddle positioned above a dissolution vessel?

• Basket (Apparatus I)
• Paddle (Apparatus II)
• Flow-through cell (Apparatus IV)
• Reciprocating cylinder (Apparatus III)

Correct Answer: Paddle (Apparatus II)

Q2. What is the primary purpose of maintaining sink conditions during a dissolution test?

• To prevent microbial growth in the medium
• To ensure the surface area of the dosage form remains constant
• To keep drug concentration well below its saturation solubility so dissolution is not solubility-limited
• To simulate the pH of gastric fluid exactly

Correct Answer: To keep drug concentration well below its saturation solubility so dissolution is not solubility-limited

Q3. Which dissolution apparatus is preferred for products with low solubility where an absorptive receiver phase or continuous flow is required?

• Basket (Apparatus I)
• Paddle (Apparatus II)
• Flow-through cell (Apparatus IV)
• Reciprocating holder (Apparatus V)

Correct Answer: Flow-through cell (Apparatus IV)

Q4. During method validation, which parameter specifically assesses the ability of a dissolution method to detect changes in formulation or manufacturing that affect performance?

• Accuracy
• Robustness
• Discriminatory power
• Repeatability

Correct Answer: Discriminatory power

Q5. Which factor has the greatest direct impact on hydrodynamic conditions inside the vessel for paddle and basket apparatus?

• Rotation speed of the paddle or basket
• Chemical stability of the drug
• UV detection wavelength
• Type of dissolution media container material

Correct Answer: Rotation speed of the paddle or basket

Q6. In a dissolution test using Apparatus I (basket), what is a common modification used for capsules to prevent floating?

• Use of higher rotation speed
• Use of sinkers to weigh down the basket
• Adding surfactant to the medium only
• Decreasing medium volume below recommended level

Correct Answer: Use of sinkers to weigh down the basket

Q7. Which dissolution medium property is most critical when developing a method intended to be biorelevant for an enteric-coated tablet?

• Viscosity at room temperature
• pH and buffer capacity that simulate intestinal fluid
• Presence of alcohol as co-solvent
• Conductivity of the medium

Correct Answer: pH and buffer capacity that simulate intestinal fluid

Q8. What does the f2 similarity factor compare between two dissolution profiles?

• Difference in initial dissolution rate only
• Overall similarity of percent dissolved at multiple time points
• Absolute area under the dissolution curve only
• Time to reach 50% dissolution only

Correct Answer: Overall similarity of percent dissolved at multiple time points

Q9. Which of the following is a typical approach to maintain sink conditions for poorly soluble drugs during dissolution testing?

• Decrease rotation speed to reduce dissolution rate
• Increase volume of dissolution medium or add solubilizing agents like surfactants
• Lower the temperature below 37°C
• Use solid-phase extraction for sampling

Correct Answer: Increase volume of dissolution medium or add solubilizing agents like surfactants

Q10. Which sampling strategy reduces disturbance to dissolution hydrodynamics and provides continuous monitoring in a flow-through cell?

• Manual syringe sampling through the vessel wall
• Automated on-line UV probe sampling in the flow path
• Removing and replacing the whole vessel contents at each time point
• Using dialysis tubing inside the vessel with intermittent withdrawal

Correct Answer: Automated on-line UV probe sampling in the flow path

Q11. What is intrinsic dissolution rate (IDR) primarily used for?

• To determine the dissolution profile of a formulated tablet
• To measure the dissolution of a pure drug substance from a constant surface area
• To establish sink conditions for a product
• To calibrate the UV detector

Correct Answer: To measure the dissolution of a pure drug substance from a constant surface area

Q12. Which of the following best describes a discriminatory dissolution test?

• A test that yields identical profiles regardless of formulation changes
• A test sensitive enough to detect meaningful formulation or process changes that affect in vivo performance
• A test designed only for QC release with minimal sensitivity
• A test that always uses the largest possible medium volume

Correct Answer: A test sensitive enough to detect meaningful formulation or process changes that affect in vivo performance

Q13. When comparing two dissolution profiles for equivalence, which criterion generally indicates similarity using the f2 metric?

• f2 greater than or equal to 50
• f2 less than 30
• f2 equal to 100 only
• f2 greater than 10

Correct Answer: f2 greater than or equal to 50

Q14. Which analytical correction should be applied when cumulative sampling withdraws medium volume at each time point?

• No correction is needed; use raw concentrations
• Correct for dilution by adding back the removed medium volume mathematically
• Multiply concentrations by the number of samples taken
• Only use the first sample for calculations

Correct Answer: Correct for dilution by adding back the removed medium volume mathematically

Q15. Which USP apparatus is specifically intended for ODTs (orodispersible tablets) and fragile dosage forms because of gentle agitation?

• Paddle over disk (Apparatus V)
• Reciprocating cylinder (Apparatus III)
• Paddle (Apparatus II)
• Flow-through cell (Apparatus IV)

Correct Answer: Reciprocating cylinder (Apparatus III)

Q16. Which of the following media additives is commonly used to improve wettability and solubility of poorly soluble drugs during dissolution testing?

• Acetone
• Sodium lauryl sulfate (SLS)
• Hydrochloric acid only
• Cellulose powder

Correct Answer: Sodium lauryl sulfate (SLS)

Q17. Which operational change is most likely to improve discriminatory power of a dissolution method?

• Using a very large medium volume that eliminates solubility differences
• Lowering the sampling frequency to only one time point
• Selecting a medium and hydrodynamic conditions that accentuate release differences between formulations
• Always using the same formulation as reference during development

Correct Answer: Selecting a medium and hydrodynamic conditions that accentuate release differences between formulations

Q18. Which validation attribute assesses whether a dissolution method gives consistent results under small, deliberate variations in method parameters?

• Limit of detection
• Robustness
• Specificity
• Linearity

Correct Answer: Robustness

Q19. In establishing an IVIVC, which level of correlation describes a point-to-point relationship between in vitro dissolution and the in vivo plasma concentration-time profile?

• Level A correlation
• Level B correlation
• Level C correlation
• No level correlates point-to-point

Correct Answer: Level A correlation

Q20. When developing a dissolution method for a sustained-release matrix tablet, which substitution is most appropriate to approximate in vivo mechanical stress?

• Use a lower paddle speed than for immediate release
• Switch from paddle to reciprocating cylinder to mimic peristalsis-like stress
• Eliminate buffer capacity of the medium
• Use static media without agitation

Correct Answer: Switch from paddle to reciprocating cylinder to mimic peristalsis-like stress

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