Serendipitous drug discovery examples MCQs With Answer

Introduction: This concise set of 30 MCQs on serendipitous drug discovery examples is designed for B. Pharm students to deepen understanding of drug discovery, serendipity, pharmacology, and medicinal chemistry. The questions cover classic case studies—penicillin, sildenafil (Viagra), minoxidil, chlorpromazine, cisplatin, warfarin, lithium—and probe mechanisms, historical context, safety lessons, and implications for drug repurposing. You will practice recognizing how unexpected observations, adverse effects, and clinical anecdotes led to major therapeutics and how these examples shaped regulatory and research strategies. The questions mix factual recall with application and analysis to build critical thinking for pharmaceutical sciences. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. What best defines ‘serendipitous drug discovery’?

• Discovery of therapeutic effects by targeted high-throughput screening
• Discovery of therapeutic effects by unexpected observation
• Discovery of drugs through rational computer design
• Discovery limited to plant-derived compounds only

Correct Answer: Discovery of therapeutic effects by unexpected observation

Q2. Which drug was famously discovered by Alexander Fleming in 1928 as a result of accidental contamination?

• Streptomycin
• Penicillin
• Chloramphenicol
• Tetracycline

Correct Answer: Penicillin

Q3. Sildenafil (Viagra) was originally developed to treat which condition before its serendipitous use for erectile dysfunction was found?

• Hypertension
• Depression
• Angina (cardiac ischemia)
• Epilepsy

Correct Answer: Angina (cardiac ischemia)

Q4. Which side effect of minoxidil led to its repurposing as a topical hair-growth treatment?

• Dry mouth
• Hypertrichosis (increased hair growth)
• Insomnia
• Vision loss

Correct Answer: Hypertrichosis (increased hair growth)

Q5. Which of the following mechanisms describes how penicillin exerts its antibacterial action?

• Inhibition of bacterial DNA gyrase
• Disruption of bacterial cell membrane via pore formation
• Inhibition of transpeptidase enzymes (peptidoglycan cross-linking)
• Interference with protein synthesis at 30S ribosome

Correct Answer: Inhibition of transpeptidase enzymes (peptidoglycan cross-linking)

Q6. Cisplatin’s anticancer activity was discovered unexpectedly. What is its primary molecular action?

• Topoisomerase I inhibition
• DNA cross-linking leading to apoptosis
• Microtubule stabilization
• Tyrosine kinase inhibition

Correct Answer: DNA cross-linking leading to apoptosis

Q7. Which drug’s discovery involved observing hemorrhagic disease in cattle fed spoiled sweet clover, leading to anticoagulant development?

• Heparin
• Aspirin
• Warfarin
• Diclofenac

Correct Answer: Warfarin

Q8. Chlorpromazine was first used in medicine as what, before its antipsychotic effects were realized?

• Antihypertensive
• Pre-anesthetic sedative and antiemetic
• Antibiotic
• Painkiller

Correct Answer: Pre-anesthetic sedative and antiemetic

Q9. Which of these is a key lesson from serendipitous discoveries for modern drug research?

• Serendipity eliminates the need for hypothesis-driven research
• Careful observation and follow-up of unexpected effects can yield new drugs
• Only natural products can be discovered serendipitously
• Serendipity makes clinical trials unnecessary

Correct Answer: Careful observation and follow-up of unexpected effects can yield new drugs

Q10. Who is credited with the accidental discovery of the therapeutic properties of penicillin?

• Alexander Fleming
• Selman Waksman
• Howard Florey
• Ernst Chain

Correct Answer: Alexander Fleming

Q11. Which discovery is an example of drug repurposing discovered through serendipity?

• Sildenafil for erectile dysfunction
• Metformin for diabetes discovered by accident
• Amoxicillin as an anticancer agent
• Insulin first found as antihypertensive

Correct Answer: Sildenafil for erectile dysfunction

Q12. John Cade’s experiments in 1949 led to the psychiatric use of which element-based treatment?

• Sodium chloride
• Lithium salts
• Magnesium sulfate
• Calcium carbonate

Correct Answer: Lithium salts

Q13. Which statement about minoxidil’s pharmacological classification is correct?

• Minoxidil is a beta blocker
• Minoxidil is a potassium channel opener and vasodilator
• Minoxidil is a selective serotonin reuptake inhibitor
• Minoxidil is a calcium channel blocker

Correct Answer: Minoxidil is a potassium channel opener and vasodilator

Q14. Cisplatin was noted to have antimicrobial effects before its anticancer use. What emphasized principle does this illustrate?

• Cross-disciplinary observation can reveal new therapeutic uses
• Only chemists can discover new drugs
• Microbial assays are irrelevant for cancer drug discovery
• Preclinical toxicity always predicts human benefit

Correct Answer: Cross-disciplinary observation can reveal new therapeutic uses

Q15. The teratogenic disaster with thalidomide led to which important regulatory change globally?

• Shorter clinical trials
• Weaker post-marketing surveillance
• Stricter drug safety testing and teratogenicity assessment
• Reduction in animal testing requirements

Correct Answer: Stricter drug safety testing and teratogenicity assessment

Q16. Which of the following is a pharmacological mechanism of sildenafil relevant to its serendipitous effect?

• Alpha-1 receptor blockade
• Inhibition of phosphodiesterase type 5 (PDE5)
• Calcium channel activation
• Monoamine oxidase inhibition

Correct Answer: Inhibition of phosphodiesterase type 5 (PDE5)

Q17. What role does careful case reporting play in serendipitous discovery?

• It delays regulatory approval
• It helps identify unexpected therapeutic effects for further investigation
• It is unnecessary if preclinical data are positive
• It only benefits marketing departments

Correct Answer: It helps identify unexpected therapeutic effects for further investigation

Q18. Which antibiotic discovery is often cited as a product of deliberate soil screening rather than pure serendipity?

• Penicillin
• Streptomycin
• Sildenafil
• Minoxidil

Correct Answer: Streptomycin

Q19. Bupropion’s use for smoking cessation is an example of what concept related to serendipitous findings?

• Targeted combinatorial chemistry
• Drug repurposing based on observed side effects
• Pharmacogenetic discovery
• Herbal medicine validation

Correct Answer: Drug repurposing based on observed side effects

Q20. Which discovery method contrasts most with serendipitous discovery?

• High-throughput screening and rational drug design
• Careful clinical observation
• Accidental contamination observation
• Repurposing based on adverse events

Correct Answer: High-throughput screening and rational drug design

Q21. The discovery of penicillin emphasized the importance of which laboratory practice?

• Ignoring contamination
• Careful record-keeping and observation of anomalies
• Only running planned experiments
• Immediate disposal of unexpected cultures

Correct Answer: Careful record-keeping and observation of anomalies

Q22. Which of the following is NOT typically a feature of serendipitous drug discoveries?

• Accidental observation or unintended effect
• Follow-up investigation validating the effect
• Rational design based solely on target structure
• Clinical or preclinical anecdote leading to repurposing

Correct Answer: Rational design based solely on target structure

Q23. What ethical consideration became more prominent after several serendipitous discoveries caused harm?

• Relief from informed consent requirements
• Enhanced preclinical safety testing and informed consent in trials
• Elimination of placebo controls
• Reduced patient monitoring during trials

Correct Answer: Enhanced preclinical safety testing and informed consent in trials

Q24. Which drug discovered serendipitously acts primarily as a dopamine D2 receptor antagonist used in psychosis?

• Chlorpromazine
• Penicillin
• Sildenafil
• Minoxidil

Correct Answer: Chlorpromazine

Q25. Observing unexpected patient improvements during trials can lead to:

• Immediate market withdrawal of the drug
• Investigation into new indications and mechanism studies
• Stopping all clinical research permanently
• Ignoring the observation as anecdotal

Correct Answer: Investigation into new indications and mechanism studies

Q26. What is an example of a molecular-level investigation that often follows a serendipitous clinical observation?

• Random marketing campaigns
• Mechanistic studies to identify target and pathway
• Anecdotal promotion without data
• Immediate large-scale distribution without trials

Correct Answer: Mechanistic studies to identify target and pathway

Q27. Which phenomenon describes finding new therapeutic use for an existing drug based on unexpected effects?

• De novo drug design
• Drug repurposing
• Targeted protein degradation
• Prodrug activation

Correct Answer: Drug repurposing

Q28. Which serendipitous discovery contributed significantly to the development of antibiotics in the 20th century?

• Discovery of cisplatin
• Discovery of penicillin
• Discovery of lithium
• Discovery of sildenafil

Correct Answer: Discovery of penicillin

Q29. Why is multidisciplinary awareness important in recognizing serendipitous discoveries?

• Because discoveries are only valid within one discipline
• Because cross-field knowledge helps interpret unexpected results and identify applications
• Because it prevents any new discoveries
• Because it reduces the need for clinical trials

Correct Answer: Because cross-field knowledge helps interpret unexpected results and identify applications

Q30. A modern approach to maximize benefits from serendipity in drug discovery is:

• Ignoring unexpected findings and focusing only on protocols
• Integrating careful observation, data mining, and systematic follow-up studies
• Eliminating clinical observation from research
• Relying solely on luck without documentation

Correct Answer: Integrating careful observation, data mining, and systematic follow-up studies

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