Cimetidine MCQs With Answer

Cimetidine MCQs With Answer provide B. Pharm students a focused review of cimetidine, an H2 receptor antagonist commonly used in peptic ulcer disease and gastroesophageal reflux. This concise set covers pharmacology, mechanism of action, pharmacokinetics, dosage forms, adverse effects like gynecomastia and CNS disturbance, and clinically relevant drug interactions through CYP450 inhibition. Questions also explore therapeutic indications including Zollinger–Ellison syndrome, renal dosing adjustments, and safety in special populations. Designed to strengthen clinical reasoning, prescribing awareness, and exam preparation, these MCQs go beyond basics to test application and safe use in practice. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which receptor does cimetidine primarily antagonize to reduce gastric acid secretion?

• H1 histamine receptor
• H2 histamine receptor
• Muscarinic M3 receptor
• Proton pump (H+/K+ ATPase)

Correct Answer: H2 histamine receptor

Q2. The main therapeutic use of cimetidine is:

• Management of bronchial asthma
• Treatment of peptic ulcer disease and reflux
• First-line therapy for hypertension
• Anticoagulation in atrial fibrillation

Correct Answer: Treatment of peptic ulcer disease and reflux

Q3. Which of the following best describes cimetidine’s effect on gastric acid secretion?

• Irreversible inhibition of proton pumps
• Competitive antagonism of histamine at parietal cell H2 receptors
• Agonism at H1 and H2 receptors to increase mucus secretion
• Neutralization of gastric acid through direct chemical buffering

Correct Answer: Competitive antagonism of histamine at parietal cell H2 receptors

Q4. Which pharmacokinetic property of cimetidine is most affected in patients with renal impairment?

• Hepatic metabolism rate
• Renal clearance and elimination half-life
• Volume of distribution in adipose tissue
• Plasma protein binding affinity

Correct Answer: Renal clearance and elimination half-life

Q5. Cimetidine inhibits certain cytochrome P450 enzymes. Which clinical consequence is most likely?

• Reduced plasma levels of warfarin
• Increased plasma concentrations of drugs metabolized by CYP enzymes, causing toxicity
• Enhanced metabolism of theophylline reducing its efficacy
• Complete prevention of drug absorption in the gut

Correct Answer: Increased plasma concentrations of drugs metabolized by CYP enzymes, causing toxicity

Q6. Which adverse effect is classically associated with cimetidine due to antiandrogenic activity?

• Hypotension
• Gynecomastia and impotence
• Severe bronchospasm
• Platelet aggregation

Correct Answer: Gynecomastia and impotence

Q7. Cimetidine is most likely to interact adversely with which of the following drugs by raising its plasma concentration?

• Metformin
• Phenytoin
• Insulin
• Furosemide

Correct Answer: Phenytoin

Q8. Regarding onset and duration of action after oral administration, cimetidine typically:

• Has immediate onset and lasts 24 hours
• Onset within about an hour and duration around 4–8 hours
• Requires several days to become effective
• Is effective only when given intravenously

Correct Answer: Onset within about an hour and duration around 4–8 hours

Q9. Which statement about cimetidine’s bioavailability and metabolism is correct?

• It has nearly 100% oral bioavailability and is not metabolized
• Oral bioavailability is moderate (around 60–70%) and it undergoes hepatic metabolism
• It is not absorbed orally and must be given intramuscularly
• It is extensively protein-bound (>99%) limiting distribution

Correct Answer: Oral bioavailability is moderate (around 60–70%) and it undergoes hepatic metabolism

Q10. For Zollinger–Ellison syndrome, cimetidine is used because:

• It stimulates gastric acid production to help digestion
• It inhibits histamine-stimulated acid secretion, lowering acid output even at high gastrin levels
• It acts as a gastrin antagonist directly at G-cells
• It neutralizes gastric acid through antacid properties

Correct Answer: It inhibits histamine-stimulated acid secretion, lowering acid output even at high gastrin levels

Q11. Which patient population requires particular caution when prescribing cimetidine due to risk of CNS adverse effects?

• Young adults with asthma
• Elderly patients and those with renal impairment
• Pregnant women in first trimester
• Patients with controlled hypertension

Correct Answer: Elderly patients and those with renal impairment

Q12. A notable endocrine effect of cimetidine is:

• Stimulation of testosterone synthesis
• Antagonism of androgen receptors leading to impotence and gynecomastia
• Reduction of prolactin causing amenorrhea
• Increased thyroid hormone production

Correct Answer: Antagonism of androgen receptors leading to impotence and gynecomastia

Q13. Which laboratory parameter might be affected by cimetidine’s interaction with warfarin?

• Elevated blood glucose
• Prolonged prothrombin time/INR
• Decreased serum potassium
• Increased hemoglobin

Correct Answer: Prolonged prothrombin time/INR

Q14. Which of the following is an important counseling point about cimetidine and antacid co-administration?

• Antacids accelerate cimetidine absorption and increase its effect
• Antacids may reduce cimetidine absorption if taken simultaneously; stagger the doses
• Antacids convert cimetidine to an inactive metabolite
• Antacid use eliminates cimetidine’s interaction with CYP enzymes

Correct Answer: Antacids may reduce cimetidine absorption if taken simultaneously; stagger the doses

Q15. Which route of administration is available for cimetidine in addition to oral dosing?

• Topical gel
• Intravenous injection
• Inhalation aerosol
• Transdermal patch

Correct Answer: Intravenous injection

Q16. Cimetidine’s mechanism of causing confusion and hallucinations in some patients is most related to:

• Direct stimulation of dopaminergic pathways in the brain
• High CNS penetration and accumulation especially with renal impairment
• Severe hypotension causing cerebral hypoperfusion
• Immune-mediated encephalitis

Correct Answer: High CNS penetration and accumulation especially with renal impairment

Q17. Which acid-related condition is least appropriately treated with cimetidine alone?

• Simple duodenal ulcer
• Gastroesophageal reflux disease (mild cases)
• Zollinger–Ellison syndrome requiring very high acid suppression
• Stress-related mucosal bleeding prophylaxis in ICU (when rapid control needed)

Correct Answer: Zollinger–Ellison syndrome requiring very high acid suppression

Q18. Compared to proton pump inhibitors (PPIs), H2 antagonists like cimetidine:

• Produce more prolonged and complete acid suppression than PPIs
• Are faster in onset but generally provide shorter duration of acid suppression
• Are irreversible inhibitors of acid secretion
• Have no clinically significant drug interactions

Correct Answer: Are faster in onset but generally provide shorter duration of acid suppression

Q19. What is a pharmacodynamic reason cimetidine may reduce the absorption of certain antifungal drugs like ketoconazole?

• Cimetidine increases gastric acidity, degrading ketoconazole
• Cimetidine raises gastric pH, reducing dissolution and absorption of weakly basic antifungals
• Cimetidine chemically binds and inactivates ketoconazole in the intestine
• Cimetidine increases intestinal motility, shortening residence time

Correct Answer: Cimetidine raises gastric pH, reducing dissolution and absorption of weakly basic antifungals

Q20. In terms of metabolism, which statement about cimetidine is true?

• It is exclusively eliminated unchanged in feces
• It undergoes partial hepatic metabolism and significant renal excretion
• It is converted entirely to active metabolites that account for its effect
• It induces CYP450 enzymes, increasing metabolism of other drugs

Correct Answer: It undergoes partial hepatic metabolism and significant renal excretion

Q21. Which monitoring parameter is most important when cimetidine is prescribed with drugs metabolized by CYP enzymes?

• Daily body weight
• Plasma drug concentrations or clinical signs of toxicity of the interacting drug
• Serum calcium levels
• Baseline ECG only

Correct Answer: Plasma drug concentrations or clinical signs of toxicity of the interacting drug

Q22. Which of the following best describes cimetidine’s effect on gastric pH and related drug absorption?

• Decreases gastric pH, enhancing absorption of weak bases
• Increases gastric pH, which can reduce absorption of some weakly basic drugs
• Has no effect on gastric pH
• Causes unpredictable swings in pH that do not affect drug absorption

Correct Answer: Increases gastric pH, which can reduce absorption of some weakly basic drugs

Q23. Which adverse effect is less commonly associated with cimetidine?

• Diarrhea and headache
• Severe agranulocytosis as a common occurrence
• Rash and allergic reactions
• Reversible hepatic enzyme elevations

Correct Answer: Severe agranulocytosis as a common occurrence

Q24. For outpatient management of uncomplicated duodenal ulcer, a commonly recommended cimetidine regimen is:

• Single daily injection for 2 weeks
• Oral dosing twice daily for several weeks
• Topical application to the abdomen
• High-dose intravenous infusion indefinitely

Correct Answer: Oral dosing twice daily for several weeks

Q25. Which statement about cimetidine use during pregnancy is most accurate for clinical decision-making?

• It is absolutely contraindicated in all trimesters
• Cimetidine has been used in pregnancy; risks should be weighed and alternatives considered
• It guarantees teratogenic effects in early pregnancy
• It must be used at doses 10× higher during pregnancy

Correct Answer: Cimetidine has been used in pregnancy; risks should be weighed and alternatives considered

Q26. An important pharmacovigilance concern when cimetidine is co-administered with theophylline is:

• Cimetidine markedly decreases theophylline clearance, increasing toxicity risk
• Cimetidine prevents theophylline absorption, causing therapeutic failure
• Cimetidine and theophylline chemically react in the gut to form an inactive complex
• Cimetidine causes immediate renal excretion of theophylline

Correct Answer: Cimetidine markedly decreases theophylline clearance, increasing toxicity risk

Q27. Which of the following describes a mechanism by which cimetidine can cause endocrine effects?

• Agonism at pituitary estrogen receptors increasing LH secretion
• Inhibition of hepatic cytochrome-mediated steroid metabolism and direct antiandrogenic receptor effects
• Stimulating testicular androgen production
• Blocking cortisol receptors in peripheral tissues

Correct Answer: Inhibition of hepatic cytochrome-mediated steroid metabolism and direct antiandrogenic receptor effects

Q28. Which OTC behavior could reduce the effectiveness of cimetidine therapy?

• Taking cimetidine at night only for nocturnal symptoms
• Concurrent heavy use of proton pump inhibitors without guidance
• Adhering strictly to prescribed dosing times
• Avoiding smoking and NSAIDs

Correct Answer: Concurrent heavy use of proton pump inhibitors without guidance

Q29. Which statement about cimetidine and hepatic enzyme interactions is correct?

• Cimetidine is a strong inducer of CYP450 enzymes
• Cimetidine is a reversible inhibitor of several CYP450 isoforms, potentially increasing levels of coadministered drugs
• Cimetidine has no effect on hepatic enzymes and therefore no interactions
• Cimetidine permanently inactivates CYP enzymes requiring enzyme replacement

Correct Answer: Cimetidine is a reversible inhibitor of several CYP450 isoforms, potentially increasing levels of coadministered drugs

Q30. When counselling a patient on cimetidine, which instruction is most appropriate to minimize interaction with other oral drugs?

• Take cimetidine together with all other oral medications to improve compliance
• Space cimetidine and other critical oral medications by 1–2 hours and monitor for interactions
• Double the dose of cimetidine if another drug is being taken concurrently
• Avoid drinking water with cimetidine to prevent dilution

Correct Answer: Space cimetidine and other critical oral medications by 1–2 hours and monitor for interactions

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