Omeprazole MCQs With Answer

Omeprazole MCQs With Answer

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Omeprazole MCQs With Answer provides B.Pharm students a focused, clinically relevant review of omeprazole—an important proton pump inhibitor (PPI). This introduction covers mechanism of action, pharmacodynamics, pharmacokinetics (CYP2C19 metabolism, bioavailability), clinical uses (GERD, peptic ulcer disease, Zollinger‑Ellison), drug interactions (clopidogrel, ketoconazole), adverse effects (hypomagnesemia, C. difficile risk), dosing, formulations and monitoring. Each MCQ emphasizes key pharmacy concepts like prodrug activation, irreversible H+/K+ ATPase inhibition, formulation considerations and long‑term safety to strengthen therapeutic decision‑making and exam readiness. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which statement best describes omeprazole’s primary mechanism of action?

  • Reversible antagonism of histamine H2 receptors on parietal cells
  • Competitive inhibition of the gastric proton pump without covalent bonding
  • Prodrug activation in acidic canaliculi followed by irreversible inhibition of H+/K+ ATPase
  • Neutralization of gastric acid through bicarbonate release

Correct Answer: Prodrug activation in acidic canaliculi followed by irreversible inhibition of H+/K+ ATPase

Q2. Omeprazole belongs to which pharmacological class?

  • H2 receptor antagonist
  • Proton pump inhibitor (PPI)
  • Anticholinergic acid suppressor
  • Gastric mucosal protectant

Correct Answer: Proton pump inhibitor (PPI)

Q3. Omeprazole is administered as a prodrug because:

  • It is active in neutral pH and must be converted to inactive form in stomach
  • It requires activation in the acidic environment of parietal cell secretory canaliculi to form the active sulfenamide
  • It is unstable in plasma and must be metabolized by the liver to become active
  • Activation occurs in the intestine by bacterial enzymes

Correct Answer: It requires activation in the acidic environment of parietal cell secretory canaliculi to form the active sulfenamide

Q4. Which cytochrome P450 enzyme is most important for omeprazole metabolism?

  • CYP1A2
  • CYP2C19
  • CYP2D6
  • CYP4A11

Correct Answer: CYP2C19

Q5. A clinically significant drug interaction with omeprazole involves reduced activation of which antiplatelet prodrug?

  • Ticagrelor
  • Clopidogrel
  • Warfarin
  • Aspirin

Correct Answer: Clopidogrel

Q6. Long-term omeprazole therapy is associated with which of the following adverse effects?

  • Hypomagnesemia
  • Hypokalemia due to renal wasting
  • Acute hypercalcemia
  • Hyperthyroidism

Correct Answer: Hypomagnesemia

Q7. When is the optimal time to administer an oral omeprazole dose for maximum acid suppression?

  • At bedtime on an empty stomach
  • Immediately after a large meal
  • 30–60 minutes before breakfast
  • Anytime without regard to meals

Correct Answer: 30–60 minutes before breakfast

Q8. Why are many omeprazole oral formulations enteric-coated?

  • To enhance renal elimination
  • To prevent acid-mediated degradation of the prodrug in the stomach
  • To deliver the drug directly to the colon
  • To increase the hydrophilicity of the molecule

Correct Answer: To prevent acid-mediated degradation of the prodrug in the stomach

Q9. Concomitant use of omeprazole can reduce absorption of which drug due to increased gastric pH?

  • Ketoconazole
  • Metformin
  • Levothyroxine
  • Amoxicillin

Correct Answer: Ketoconazole

Q10. What explains the prolonged duration of acid suppression by omeprazole despite its short plasma half-life?

  • Omeprazole accumulates in adipose tissue for prolonged release
  • Irreversible covalent inhibition of H+/K+ ATPase requires synthesis of new pumps for acid recovery
  • Long enterohepatic recirculation maintains plasma levels
  • Active metabolites have very long half-lives

Correct Answer: Irreversible covalent inhibition of H+/K+ ATPase requires synthesis of new pumps for acid recovery

Q11. In H. pylori eradication regimens omeprazole primarily contributes by:

  • Direct bactericidal activity against H. pylori
  • Neutralizing antibiotic adverse effects
  • Raising intragastric pH to enhance antibiotic stability and efficacy
  • Enhancing gastric motility to expel bacteria

Correct Answer: Raising intragastric pH to enhance antibiotic stability and efficacy

Q12. Omeprazole is a racemic mixture; which marketed drug is the S‑enantiomer developed for higher bioavailability?

  • Lansoprazole
  • Esomeprazole
  • Rabeprazole
  • Pantoprazole

Correct Answer: Esomeprazole

Q13. Full antisecretory effect of omeprazole typically requires several days of dosing because:

  • Omeprazole must accumulate in the liver before acting
  • Only active pumps stimulated during meals are irreversibly inhibited and new pumps are synthesized over days
  • The drug needs conversion to an active metabolite in the kidney
  • It takes time to reach steady-state plasma concentration due to long half-life

Correct Answer: Only active pumps stimulated during meals are irreversibly inhibited and new pumps are synthesized over days

Q14. CYP2C19 genetic polymorphisms affect omeprazole exposure such that rapid metabolizers typically have:

  • Higher plasma concentrations and greater acid suppression
  • Lower plasma concentrations and reduced acid suppression
  • Increased risk of hypomagnesemia
  • No change in pharmacodynamic effect

Correct Answer: Lower plasma concentrations and reduced acid suppression

Q15. Which condition is an approved high-dose indication for omeprazole therapy?

  • Functional dyspepsia without ulceration
  • Zollinger‑Ellison syndrome
  • Irritable bowel syndrome
  • Acute pancreatitis

Correct Answer: Zollinger‑Ellison syndrome

Q16. A serious but uncommon renal adverse effect reported with PPIs including omeprazole is:

  • Acute tubular necrosis
  • Acute interstitial nephritis
  • Nephrolithiasis due to hyperoxaluria
  • Membranous nephropathy

Correct Answer: Acute interstitial nephritis

Q17. Long-term acid suppression with omeprazole may impair absorption of which vitamin leading to deficiency?

  • Vitamin C
  • Vitamin B12 (cobalamin)
  • Vitamin D
  • Vitamin K

Correct Answer: Vitamin B12 (cobalamin)

Q18. Which laboratory parameter is recommended to monitor in patients on prolonged omeprazole therapy?

  • Serum magnesium
  • Serum phosphate
  • Serum lactate
  • Serum uric acid

Correct Answer: Serum magnesium

Q19. Which amino acid residue on the H+/K+ ATPase does the active omeprazole metabolite primarily bind to?

  • Serine
  • Cysteine
  • Tyrosine
  • Histidine

Correct Answer: Cysteine

Q20. Omeprazole oral bioavailability is affected by food such that:

  • Food increases peak concentration and should be taken with meals for best effect
  • Food has no effect on absorption
  • Food decreases absorption; therefore, it is recommended before meals
  • Food converts omeprazole to active drug in the stomach

Correct Answer: Food decreases absorption; therefore, it is recommended before meals

Q21. Which statement about routes of administration for omeprazole is correct?

  • Omeprazole is available only as an oral tablet
  • Omeprazole can be administered orally and intravenously
  • Omeprazole is available only as an intravenous infusion
  • Omeprazole is administered intramuscularly for emergency use

Correct Answer: Omeprazole can be administered orally and intravenously

Q22. Typical once‑daily omeprazole dosing for uncomplicated GERD is aimed to be given:

  • Before the largest evening meal
  • Once daily before breakfast
  • Only as needed for breakthrough symptoms
  • Every 8 hours around the clock

Correct Answer: Once daily before breakfast

Q23. Discontinuation of long-term omeprazole therapy can cause rebound acid hypersecretion because of:

  • Permanent upregulation of parietal cell proton pumps
  • Transient hypergastrinemia stimulating increased acid secretion
  • Accumulation of active drug in parietal cells
  • Reduction in intrinsic factor production

Correct Answer: Transient hypergastrinemia stimulating increased acid secretion

Q24. Which clinical scenario warrants checking magnesium level in a patient on chronic omeprazole?

  • New onset muscle cramps or tetany
  • Controlled GERD with no symptoms
  • Intermittent headache only
  • Mild seasonal allergies

Correct Answer: New onset muscle cramps or tetany

Q25. Compared to omeprazole, esomeprazole was developed primarily to:

  • Provide a racemic mixture for broader action
  • Reduce cost and increase over‑the‑counter availability
  • Offer the S‑enantiomer with improved pharmacokinetic profile and higher bioavailability
  • Eliminate need for enteric coating

Correct Answer: Offer the S‑enantiomer with improved pharmacokinetic profile and higher bioavailability

Q26. Which of the following is a legitimate concern when prescribing omeprazole with long-term NSAID therapy?

  • Omeprazole increases NSAID-induced bleeding
  • Omeprazole prevents NSAID-induced peptic ulcers and is used for gastroprotection
  • Omeprazole potentiates NSAID analgesic effect
  • Omeprazole accelerates NSAID renal clearance

Correct Answer: Omeprazole prevents NSAID-induced peptic ulcers and is used for gastroprotection

Q27. Which patient genotype would likely have increased omeprazole exposure and greater acid suppression?

  • CYP2C19 ultrarapid metabolizer
  • CYP2C19 poor metabolizer
  • CYP3A4 poor metabolizer only
  • No relevance of genotype to omeprazole levels

Correct Answer: CYP2C19 poor metabolizer

Q28. A pharmacist counseling a patient on omeprazole should advise that long-term use may increase the risk of:

  • Vitamin B12 deficiency and bone fractures
  • Hepatic fibrosis
  • Acute myocardial infarction
  • Hyperkalemia

Correct Answer: Vitamin B12 deficiency and bone fractures

Q29. Which of the following describes why omeprazole can reduce the efficacy of atazanavir (an antiretroviral)?

  • Omeprazole induces CYP2D6 which metabolizes atazanavir
  • Increased gastric pH reduces atazanavir absorption leading to subtherapeutic levels
  • Omeprazole competes with atazanavir for renal excretion
  • Omeprazole binds directly to atazanavir reducing its potency

Correct Answer: Increased gastric pH reduces atazanavir absorption leading to subtherapeutic levels

Q30. The primary cellular site of action for omeprazole within the stomach is:

  • Mucous neck cells secreting mucin
  • Chief cells secreting pepsinogen
  • Parietal cell secretory canaliculi containing H+/K+ ATPase
  • Surface epithelial cells producing bicarbonate

Correct Answer: Parietal cell secretory canaliculi containing H+/K+ ATPase

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