Introduction to drug design MCQs With Answer

Introduction to drug design MCQs With Answer

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Introduction to drug design MCQs With Answer

Drug design is a core area of medicinal chemistry that covers target identification, lead discovery, structure–activity relationship (SAR), lead optimization, and ADME/pharmacokinetics considerations. This set of MCQs with answers for B. Pharm students focuses on key concepts such as molecular docking, QSAR, pharmacodynamics, prodrugs, combinatorial chemistry, bioisosterism, and toxicity prediction. Practicing these questions strengthens understanding of drug–receptor interactions, rational design strategies, computational tools, and experimental validation. These MCQs are designed to improve problem-solving skills, exam readiness, and application of theoretical knowledge to practical drug development scenarios. Each answer includes concise explanations to reinforce learning and link concepts to B. Pharm coursework. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which principle explains how small structural changes in a molecule alter its biological activity and is central to medicinal chemistry?

  • Pharmacokinetics
  • Structure–Activity Relationship
  • Bioavailability
  • First-pass metabolism

Correct Answer: Structure–Activity Relationship

Q2. What does QSAR primarily correlate with biological activity to predict potency?

  • Clinical adverse effects
  • Molecular descriptors and physicochemical properties
  • Patient demographics
  • Manufacturing yield

Correct Answer: Molecular descriptors and physicochemical properties

Q3. Which computational technique evaluates the preferred orientation of a ligand when bound to a protein target?

  • Molecular docking
  • NMR spectroscopy
  • High-performance liquid chromatography
  • In vitro dissolution testing

Correct Answer: Molecular docking

Q4. Which property is NOT part of Lipinski’s Rule of Five for oral drug-likeness?

  • Molecular weight under 500 Da
  • No more than 5 hydrogen bond donors
  • Log P less than 5
  • Polar surface area less than 60 Ų

Correct Answer: Polar surface area less than 60 Ų

Q5. Bioisosteric replacement is used in drug design mainly to:

  • Increase tablet hardness during formulation
  • Modify biological properties while retaining activity
  • Change a drug’s packaging label
  • Sterilize injectable formulations

Correct Answer: Modify biological properties while retaining activity

Q6. Which descriptor measures lipophilicity often used in drug design and ADME prediction?

  • pKa
  • Log P (partition coefficient)
  • Molar refractivity
  • Boiling point

Correct Answer: Log P (partition coefficient)

Q7. Fragment-based drug design primarily relies on:

  • Large combinatorial libraries of very complex molecules
  • Screening low-molecular-weight fragments that bind weakly
  • Exclusive use of natural products
  • Only in vivo efficacy studies

Correct Answer: Screening low-molecular-weight fragments that bind weakly

Q8. In QSAR, which of the following is an example of a molecular descriptor?

  • Color of the powder
  • Topological polar surface area (TPSA)
  • Expiry date
  • Supplier name

Correct Answer: Topological polar surface area (TPSA)

Q9. Which in silico method predicts metabolism sites and potential metabolites?

  • Pharmacophore mapping
  • ADMET prediction tools / Metabolism prediction software
  • Wet lab solubility testing
  • Microbial assay

Correct Answer: ADMET prediction tools / Metabolism prediction software

Q10. Which parameter describes the concentration of inhibitor that reduces enzyme activity by 50% and is used to compare inhibitor potency?

  • MIC
  • IC50
  • Cmax
  • t1/2

Correct Answer: IC50

Q11. Which strategy improves selectivity and decreases off-target toxicity during lead optimization?

  • Increasing lipophilicity indiscriminately
  • Structure-based design to exploit unique target features
  • Removing all polar groups
  • Maximizing molecular weight

Correct Answer: Structure-based design to exploit unique target features

Q12. Which class of compounds can be used as prodrugs to improve oral absorption?

  • Highly charged quaternary ammonium salts
  • Ester or amide prodrugs that are cleaved in vivo
  • Non-metabolizable inert polymers
  • Metal complexes

Correct Answer: Ester or amide prodrugs that are cleaved in vivo

Q13. Which experimental method provides direct structural information about ligand–receptor complexes to guide rational design?

  • X-ray crystallography
  • Partition coefficient measurement
  • Mass spectrometry of formulation
  • Colorimetric assay

Correct Answer: X-ray crystallography

Q14. What is the main advantage of high-throughput screening (HTS) in lead discovery?

  • It guarantees clinical success
  • It evaluates thousands to millions of compounds rapidly against a target
  • It replaces medicinal chemistry optimization
  • It measures ADME properties directly

Correct Answer: It evaluates thousands to millions of compounds rapidly against a target

Q15. Which pharmacokinetic parameter describes the fraction of an administered dose that reaches systemic circulation?

  • Bioavailability (F)
  • Volume of distribution (Vd)
  • Clearance (Cl)
  • Maximum tolerated dose

Correct Answer: Bioavailability (F)

Q16. What is a pharmacophore model used for in drug design?

  • Predicting tablet dissolution time
  • Describing the spatial arrangement of features necessary for biological activity
  • Determining toxicity classification in animals
  • Labeling commercial batches

Correct Answer: Describing the spatial arrangement of features necessary for biological activity

Q17. Which term describes the improvement of ADME properties while maintaining potency?

  • Lead discovery
  • Lead optimization
  • Target validation
  • Formulation screening

Correct Answer: Lead optimization

Q18. Which measurement estimates a drug’s binding affinity to a receptor in thermodynamic terms?

  • Hill coefficient
  • Ki (inhibition constant)
  • LD50
  • pH of the formulation

Correct Answer: Ki (inhibition constant)

Q19. Combinatorial chemistry accelerates lead generation by:

  • Systematic synthesis of large libraries of related compounds
  • Always producing orally active drugs
  • Eliminating the need for screening assays
  • Focusing only on natural product isolation

Correct Answer: Systematic synthesis of large libraries of related compounds

Q20. Which of the following is a common molecular descriptor used in QSAR reflecting electronic effects?

  • Hammett sigma constant
  • Tablet hardness
  • Refractive index of solvent
  • Melting point of excipient

Correct Answer: Hammett sigma constant

Q21. Which class of drugs typically requires special design considerations due to high molecular weight and poor membrane permeability?

  • Small-molecule enzyme inhibitors
  • Biologics such as monoclonal antibodies and peptides
  • Volatile anesthetics
  • Simple salts like sodium chloride

Correct Answer: Biologics such as monoclonal antibodies and peptides

Q22. Which technique ranks ligand poses by predicted binding energy during docking?

  • Scoring functions
  • Thin-layer chromatography
  • ELISA
  • Gel electrophoresis

Correct Answer: Scoring functions

Q23. Which ADME parameter most directly influences dosing frequency for a drug?

  • Melting point
  • Plasma half-life (t1/2)
  • Color of tablet
  • Supplier lead time

Correct Answer: Plasma half-life (t1/2)

Q24. Which is an example of a successful bioisostere used to reduce metabolic liability?

  • Replacing a hydrogen with helium
  • Replacing a metabolically labile methyl with a fluorine
  • Replacing carbon with gold
  • Replacing oxygen with silicon in all cases

Correct Answer: Replacing a metabolically labile methyl with a fluorine

Q25. Which guideline classifies drugs based on solubility and permeability to aid formulation strategy?

  • ICH Q10
  • Biopharmaceutics Classification System (BCS)
  • Good Manufacturing Practice (GMP)
  • OECD GLP

Correct Answer: Biopharmaceutics Classification System (BCS)

Q26. Which in vitro assay is commonly used to assess a compound’s metabolic stability in liver?

  • Microsomal stability assay
  • Molecular docking
  • UV-Vis spectroscopy of pure solvent
  • pH titration

Correct Answer: Microsomal stability assay

Q27. Which factor is most important when designing a drug to cross the blood–brain barrier?

  • Very high polar surface area
  • Appropriate lipophilicity and low P-gp efflux liability
  • Heavy metal content
  • High plasma protein binding only

Correct Answer: Appropriate lipophilicity and low P-gp efflux liability

Q28. Which metric compares potency across different assays by normalizing to target occupancy or effect?

  • IC50/Emax relationships and Ki considerations
  • Tablet disintegration time
  • Manufacturing batch size
  • Package insert length

Correct Answer: IC50/Emax relationships and Ki considerations

Q29. Which approach integrates multiple disciplines (chemistry, biology, informatics) to accelerate drug discovery?

  • Interdisciplinary drug design and translational research
  • Single-subject case reports
  • Only empirical animal screening without chemistry input
  • Exclusive focus on marketing

Correct Answer: Interdisciplinary drug design and translational research

Q30. Which statement best describes “lead-likeness” in early drug discovery?

  • Leads should always have molecular weight >900 Da
  • Leads possess balanced physicochemical properties suitable for optimization
  • Leads must be final marketed products
  • Leads should never be modified chemically

Correct Answer: Leads possess balanced physicochemical properties suitable for optimization

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