Tolerance MCQs With Answer

Tolerance MCQs With Answer is an essential study set for B. Pharm students to master the pharmacological concept of tolerance. This introduction covers drug tolerance, tachyphylaxis, cross-tolerance, pharmacokinetic and pharmacodynamic mechanisms, receptor desensitization, metabolic induction, and clinical implications like dose escalation and withdrawal. Understanding measurement methods (ED50 shifts, dose–response curves) and real-world examples (opioids, benzodiazepines, nitrates) strengthens rational dosing and patient safety. These targeted MCQs emphasize mechanism-based reasoning, therapeutic strategies to manage tolerance, and differences from dependence or resistance. Use these questions to sharpen exam skills, clinical judgment, and pharmacology fundamentals. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. What is the most accurate definition of pharmacological tolerance?

• A decrease in drug effect after repeated administration requiring higher doses to achieve the same effect
• An immediate allergic reaction to a single drug exposure
• A permanent genetic resistance to a drug
• An increase in drug potency over time

Correct Answer: A decrease in drug effect after repeated administration requiring higher doses to achieve the same effect

Q2. Which mechanism primarily describes pharmacodynamic tolerance?

• Increased hepatic metabolism of a drug
• Enhanced renal excretion of a drug
• Receptor downregulation or desensitization at the target site
• Reduced absorption from the gastrointestinal tract

Correct Answer: Receptor downregulation or desensitization at the target site

Q3. Tachyphylaxis is best defined as:

• Slowly developing tolerance over months
• A rapid decrease in response to a drug after repeated doses in a short time
• Genetic mutation causing drug resistance
• Cross-reactivity between two unrelated drugs

Correct Answer: A rapid decrease in response to a drug after repeated doses in a short time

Q4. Which example is most characteristic of metabolic tolerance?

• Opioid receptor internalization after chronic opioid use
• Induction of CYP450 enzymes leading to faster drug clearance
• Reduced agonist affinity for the receptor
• Immediate immune-mediated drug neutralization

Correct Answer: Induction of CYP450 enzymes leading to faster drug clearance

Q5. Cross-tolerance means:

• Tolerance to one drug decreases sensitivity to a different drug with a similar mechanism
• Tolerance always transfers between drugs in different classes
• Tolerance that only affects the liver enzymes
• Permanent immunity to drug effects

Correct Answer: Tolerance to one drug decreases sensitivity to a different drug with a similar mechanism

Q6. Which statement distinguishes tolerance from dependence?

• Tolerance always causes withdrawal symptoms
• Dependence is physiological adaptation; tolerance is reduced response to the same dose
• Tolerance and dependence are identical phenomena
• Dependence refers exclusively to liver enzyme induction

Correct Answer: Dependence is physiological adaptation; tolerance is reduced response to the same dose

Q7. How is tolerance typically detected experimentally using dose–response curves?

• A leftward shift in dose–response curve indicating increased potency
• A rightward shift in dose–response curve indicating reduced potency
• An increase in maximal efficacy only
• No change in curve position or shape

Correct Answer: A rightward shift in dose–response curve indicating reduced potency

Q8. Which drug class commonly shows rapid tachyphylaxis with continuous exposure?

• Nitrates (e.g., nitroglycerin)
• Beta-lactam antibiotics
• Thyroid hormones
• Anticoagulants

Correct Answer: Nitrates (e.g., nitroglycerin)

Q9. Which clinical strategy can reduce development of tolerance to opioids?

• Continuous high-dose infusion without breaks
• Rotation to a different opioid (opioid rotation)
• Immediate discontinuation when tolerance appears
• Avoiding multimodal analgesia

Correct Answer: Rotation to a different opioid (opioid rotation)

Q10. Which laboratory observation indicates pharmacokinetic tolerance?

• Decreased plasma concentration at steady state for same dosing regimen due to increased clearance
• Increased receptor density on target cells
• Greater effect at same plasma concentration
• No change in plasma levels despite enzyme induction

Correct Answer: Decreased plasma concentration at steady state for same dosing regimen due to increased clearance

Q11. Receptor downregulation as a tolerance mechanism typically results from:

• Chronic agonist stimulation causing decreased receptor number on cell surface
• Acute antagonist administration
• Increased drug absorption in gut
• Enhanced renal excretion of drug metabolites

Correct Answer: Chronic agonist stimulation causing decreased receptor number on cell surface

Q12. Which measure best quantifies tolerance in pharmacology?

• Change in ED50 or EC50 for a drug
• Height of peak plasma concentration only
• Number of doses administered
• Molecular weight of the drug

Correct Answer: Change in ED50 or EC50 for a drug

Q13. Tolerance reversible over time after stopping the drug is termed:

• Permanent tolerance
• Acquired immunological tolerance
• Reversible or transient tolerance
• Pharmacogenetic tolerance

Correct Answer: Reversible or transient tolerance

Q14. Which of the following promotes metabolic tolerance?

• Inhibition of CYP enzymes
• Induction of hepatic drug-metabolizing enzymes
• Increased receptor coupling efficiency
• Decreased renal blood flow

Correct Answer: Induction of hepatic drug-metabolizing enzymes

Q15. Which example best illustrates cross-tolerance?

• Chronic alcohol use reducing benzodiazepine sensitivity
• Antibiotic resistance in bacteria
• Allergic reaction to penicillin after cephalosporin use
• Prolonged diuretic use causing hyperkalemia

Correct Answer: Chronic alcohol use reducing benzodiazepine sensitivity

Q16. Which term describes tolerance that occurs due to cellular processes reducing receptor signaling efficiency without changing receptor numbers?

• Receptor downregulation
• Pharmacokinetic tolerance
• Receptor desensitization (uncoupling)
• Genetic tolerance

Correct Answer: Receptor desensitization (uncoupling)

Q17. In opioid tolerance, which outcome is most likely with chronic use?

• Increased analgesic effect at same dose
• Requirement for higher doses to maintain analgesia
• Immediate hypersensitivity reactions
• Permanent cure of pain condition

Correct Answer: Requirement for higher doses to maintain analgesia

Q18. Which pharmacological phenomenon is NOT a form of tolerance?

• Tachyphylaxis
• Cross-tolerance
• Antibiotic resistance due to bacterial mutation
• Metabolic tolerance due to enzyme induction

Correct Answer: Antibiotic resistance due to bacterial mutation

Q19. A rightward shift of the dose–response curve with unchanged maximal effect indicates:

• Decreased efficacy but same potency
• Increased potency
• Reduced potency with preserved efficacy (surmountable antagonism or tolerance)
• Non-competitive antagonism

Correct Answer: Reduced potency with preserved efficacy (surmountable antagonism or tolerance)

Q20. Which clinical implication is directly associated with tolerance development?

• Need to reduce dose over time to avoid toxicity
• Possible requirement for dose escalation to maintain therapeutic effect
• Guaranteed therapy failure in all patients
• Elimination of adverse effects permanently

Correct Answer: Possible requirement for dose escalation to maintain therapeutic effect

Q21. Which test would help distinguish pharmacokinetic from pharmacodynamic tolerance?

• Measuring plasma drug concentrations after a standard dose
• Asking patient about adherence only
• Imaging receptor internalization directly in clinic
• Measuring urine pH

Correct Answer: Measuring plasma drug concentrations after a standard dose

Q22. Which intervention can prevent tachyphylaxis to topical decongestants?

• Continuous daily use without breaks
• Intermittent use or limiting duration of therapy
• Doubling the dose each application
• Concurrent antihistamine application

Correct Answer: Intermittent use or limiting duration of therapy

Q23. Which statement about tolerance and efficacy is true?

• Tolerance always reduces maximal efficacy
• Tolerance never affects potency
• Tolerance may reduce potency (shift ED50) without altering maximal efficacy
• Tolerance always increases drug clearance but not effect

Correct Answer: Tolerance may reduce potency (shift ED50) without altering maximal efficacy

Q24. Which of the following is a clinical sign that tolerance may be developing?

• Stable therapeutic response with same dose
• Decreased response requiring dose increase for same effect
• Improved side-effect profile over time without dose change
• Sudden allergic reaction on first exposure

Correct Answer: Decreased response requiring dose increase for same effect

Q25. Which is true about tolerance reversal strategies?

• Increasing dose is the only safe method to reverse tolerance
• Drug holidays, switching drugs, or adjunctive therapies can restore sensitivity
• Tolerance reversal is impossible once established
• Only genetic therapy can reverse tolerance

Correct Answer: Drug holidays, switching drugs, or adjunctive therapies can restore sensitivity

Q26. Which drug class commonly shows tolerance through receptor internalization and desensitization?

• Beta-2 agonists used as bronchodilators
• Thiazide diuretics
• Proton pump inhibitors
• Insulin preparations

Correct Answer: Beta-2 agonists used as bronchodilators

Q27. Which factor does NOT contribute to variability in tolerance among patients?

• Genetic polymorphisms in metabolizing enzymes
• Concomitant enzyme-inducing drugs
• Patient body weight and age
• Color of tablets

Correct Answer: Color of tablets

Q28. In designing MCQs for tolerance understanding, which focus improves deeper learning?

• Asking only definitional recall questions
• Including mechanism-based clinical scenarios and interpretation of dose–response changes
• Only testing brand names
• Using ambiguous options without context

Correct Answer: Including mechanism-based clinical scenarios and interpretation of dose–response changes

Q29. Which best describes opioid tolerance vs opioid-induced hyperalgesia?

• Tolerance is decreased drug effect; hyperalgesia is increased pain sensitivity due to opioid exposure
• They are identical and interchangeable terms
• Hyperalgesia always results from drug underdosing
• Tolerance causes permanent nerve damage

Correct Answer: Tolerance is decreased drug effect; hyperalgesia is increased pain sensitivity due to opioid exposure

Q30. For exam preparation on tolerance, which study approach is most effective for B. Pharm students?

• Rote memorization of single definitions without application
• Integrating mechanistic concepts, clinical examples, dose–response interpretation, and MCQ practice
• Only reading drug brand brochures
• Avoiding practice questions entirely

Correct Answer: Integrating mechanistic concepts, clinical examples, dose–response interpretation, and MCQ practice

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

Mail- Sachin@pharmacyfreak.com