Bioassay of official drugs MCQs With Answer

Introduction: Bioassay of official drugs MCQs With Answer is designed for M.Pharm students to reinforce core principles and practical aspects of biological evaluation of drug therapy. This collection focuses on pharmacopeial bioassays used for potency and activity determination of biological and pharmacologically active substances. Questions cover types of bioassays, experimental models, statistical analysis (parallel line, slope-ratio), validation parameters, regulatory expectations and ethical considerations. Each MCQ promotes deeper understanding of assay design, controls, dose–response interpretation, and data analysis necessary for accurate potency estimation and quality control of official drugs. Use these MCQs for self-assessment, revision and exam preparation.

Q1. Which bioassay design is most appropriate when the test and standard preparations have parallel dose–response curves with identical slopes?

• Comparative quantal assay
• Parallel-line assay
• Single-point assay
• Slope-ratio assay

Correct Answer: Parallel-line assay

Q2. In slope–ratio bioassay, potency is estimated by comparing which of the following?

• The ED50 values of standard and test
• The intercepts of regression lines
• The slopes of log-dose versus response lines
• The maximal responses only

Correct Answer: The slopes of log-dose versus response lines

Q3. Which parameter indicates the dose required to produce 50% of the maximal effect in a graded bioassay?

• LD50
• ED50
• TC50
• IC90

Correct Answer: ED50

Q4. For a valid parallel-line assay, which assumption must be satisfied?

• Both curves must be non-linear and intersect
• Curves must be parallel and linear over the tested range
• Slope of test must be twice the slope of standard
• Responses must saturate at different maxima

Correct Answer: Curves must be parallel and linear over the tested range

Q5. Which statistical test is commonly used to check the parallelism between dose–response lines in bioassay analysis?

• Chi-square test
• F-test (analysis of variance)
• Student’s t-test for paired samples
• Kruskal–Wallis test

Correct Answer: F-test (analysis of variance)

Q6. When performing a quantal bioassay, what is the typical endpoint measured?

• Continuous magnitude of response (e.g., blood pressure)
• Binary outcome such as presence/absence of effect
• Time to onset of effect as continuous variable
• Enzyme activity expressed as a percentage

Correct Answer: Binary outcome such as presence/absence of effect

Q7. Which regulatory document or guide is most relevant for validating bioassays for biological medicinal products?

• ICH Q2(R1) – Validation of Analytical Procedures
• ICH Q9 – Quality Risk Management
• WHO Guidelines on nonclinical evaluation
• ICH Q5E – Comparability of Biotechnological Products

Correct Answer: ICH Q2(R1) – Validation of Analytical Procedures

Q8. What does the term “potency” specifically refer to in the context of bioassays for official drugs?

• The safety margin of a drug
• The amount of drug required to produce a defined effect
• The maximal possible effect irrespective of dose
• The rate of drug metabolism in vivo

Correct Answer: The amount of drug required to produce a defined effect

Q9. Which control is essential in every bioassay to demonstrate that the biological system is responsive?

• Vehicle control alone
• Positive (reference) control or standard
• Negative bacterial contamination control
• Blank reagent control with dye only

Correct Answer: Positive (reference) control or standard

Q10. Which of the following is a major advantage of in vitro bioassays over in vivo bioassays?

• They always produce more predictive clinical outcomes
• Lower variability and better ethical profile
• No requirement for validation
• They do not require reference standards

Correct Answer: Lower variability and better ethical profile

Q11. In a bioassay, what does the term “relative potency” mean?

• The ratio of toxic dose to effective dose
• The potency of a test preparation expressed relative to a reference standard
• The absolute amount of drug per tablet
• The percentage of active ingredient that is degraded

Correct Answer: The potency of a test preparation expressed relative to a reference standard

Q12. Which factor is most likely to affect the precision (reproducibility) of a bioassay?

• Using the same reference standard each time
• High biological variability of the assay system
• Strict control of temperature and timing
• Performing assays in triplicate

Correct Answer: High biological variability of the assay system

Q13. Why is logarithmic transformation of dose commonly used in bioassay data analysis?

• To linearize sigmoidal dose–response relationships for regression
• To exaggerate differences at high doses
• To convert binary outcomes into continuous variables
• To make the dose units larger and easier to handle

Correct Answer: To linearize sigmoidal dose–response relationships for regression

Q14. Which of the following best describes an ED10 in a graded dose–response bioassay?

• The dose causing a 10% mortality
• The dose producing 10% of the maximal response
• The dose that inhibits 10% of enzymatic activity
• The dose required for 10% receptor occupancy

Correct Answer: The dose producing 10% of the maximal response

Q15. What is the main ethical consideration when choosing an in vivo bioassay model for potency testing?

• Choose the most expensive animal model available
• Minimize animal use and suffering by replacing, reducing, refining (3Rs)
• Prefer large animals because results are always better
• Use unapproved procedures to save time

Correct Answer: Minimize animal use and suffering by replacing, reducing, refining (3Rs)

Q16. When an assay shows non-parallelism between standard and test, what is the most appropriate immediate action?

• Report potency without further testing
• Investigate causes (matrix effects, degradation) and redesign assay
• Average the two curves to get a compromise value
• Switch to estimating ED90 instead of ED50

Correct Answer: Investigate causes (matrix effects, degradation) and redesign assay

Q17. Which measure assesses the sensitivity of a bioassay system?

• Maximum response (Emax)
• Limit of detection and slope steepness
• Sample volume used
• Number of replicates

Correct Answer: Limit of detection and slope steepness

Q18. In potency estimation by parallel-line analysis, confidence intervals provide information about what?

• The absolute amount of impurity present
• The range of plausible values for relative potency at a given confidence level
• The exact true potency with no uncertainty
• The time required to complete the assay

Correct Answer: The range of plausible values for relative potency at a given confidence level

Q19. Which of the following is an example of a biological standard used in official bioassays?

• Reference chemical reagent with known melting point
• International Biological Standard for insulin with assigned units
• Password-protected digital certificate
• Generic tablet without potency assignment

Correct Answer: International Biological Standard for insulin with assigned units

Q20. What is the principal reason for including multiple dose levels of standard and test in a bioassay?

• To increase sample consumption unnecessarily
• To define a dose–response curve and assess linearity and parallelism
• To ensure maximal response is never reached
• To avoid the need for statistical analysis

Correct Answer: To define a dose–response curve and assess linearity and parallelism

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