Antacids: Combinations MCQs With Answer

Antacids: Combinations MCQs With Answer

Antacids are cornerstone symptomatic treatments for acid-related disorders. This focused set of MCQs covers combination antacid pharmacology, formulation principles, mechanism of acid neutralization, common combinations (aluminum hydroxide, magnesium hydroxide, calcium carbonate, sodium bicarbonate), clinical uses in GERD and peptic ulcer disease, adverse effects (constipation, diarrhea, milk-alkali syndrome, hypermagnesemia), drug interactions (chelation with tetracyclines, fluoroquinolones, reduced absorption of ketoconazole), and special considerations in renal impairment. The questions emphasize clinical relevance, formulation rationale (simethicone, alginate, buffer capacity) and exam-oriented details tailored for B. Pharm students. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What is the primary mechanism of action of antacid combinations?

• Neutralization of gastric acid by basic compounds
• Inhibition of the H+/K+ ATPase pump
• Blockade of histamine H2 receptors
• Stimulation of gastric mucus secretion

Correct Answer: Neutralization of gastric acid by basic compounds

Q2. Why are aluminum and magnesium salts often combined in antacid formulations?

• To provide systemic alkalinization and raise serum bicarbonate
• To balance the constipation of aluminum with the laxative effect of magnesium
• To increase acid secretion through rebound mechanisms
• To chelate dietary proteins and improve digestion

Correct Answer: To balance the constipation of aluminum with the laxative effect of magnesium

Q3. Which antacid provides the fastest onset of acid neutralization when taken orally?

• Calcium carbonate
• Magnesium hydroxide
• Sodium bicarbonate
• Aluminum hydroxide

Correct Answer: Sodium bicarbonate

Q4. Chronic high intake of which antacid is most classically associated with milk-alkali syndrome?

• Magnesium hydroxide
• Aluminum hydroxide
• Calcium carbonate
• Sodium bicarbonate

Correct Answer: Calcium carbonate

Q5. Which antacid component is most commonly associated with constipation as a side effect?

• Magnesium hydroxide
• Aluminum hydroxide
• Calcium carbonate
• Sodium bicarbonate

Correct Answer: Aluminum hydroxide

Q6. Which antacid salt is most likely to cause osmotic diarrhea when used in excess?

• Aluminum hydroxide
• Calcium carbonate
• Magnesium hydroxide
• Sodium bicarbonate

Correct Answer: Magnesium hydroxide

Q7. In patients with severe renal failure which antacid ions are prone to accumulation and toxicity?

• Sodium and calcium
• Aluminum and magnesium
• Calcium and bicarbonate
• Zinc and potassium

Correct Answer: Aluminum and magnesium

Q8. Chelation with which antacid components can markedly reduce absorption of tetracyclines and fluoroquinolones?

• Aluminum, magnesium and calcium salts
• Only sodium salts
• Only simethicone
• Only alginate

Correct Answer: Aluminum, magnesium and calcium salts

Q9. Which antacid is best described as a systemic alkalinizer that can generate CO2 on reaction with gastric acid?

• Calcium carbonate
• Sodium bicarbonate
• Aluminum hydroxide
• Magnesium hydroxide

Correct Answer: Sodium bicarbonate

Q10. Antacids can reduce the absorption of which of the following antifungal drugs due to increased gastric pH?

• Fluconazole
• Ketoconazole
• Caspofungin
• Amphotericin B

Correct Answer: Ketoconazole

Q11. What is the primary pharmacological role of simethicone when added to antacid combinations?

• Increase gastric pH
• Act as a systemic antacid
• Reduce surface tension of gas bubbles (defoming agent)
• Bind dietary phosphate

Correct Answer: Reduce surface tension of gas bubbles (defoming agent)

Q12. Sodium alginate in antacid formulations primarily provides which clinical benefit?

• Acts as a systemic phosphate binder
• Forms a viscous raft to prevent reflux
• Neutralizes gastric acid faster than bicarbonate
• Enhances absorption of weak acids

Correct Answer: Forms a viscous raft to prevent reflux

Q13. Buffering capacity of an antacid is most directly dependent on which factor?

• Molecular weight alone
• Concentration of weak base and its pKa relative to gastric pH
• Lipophilicity of the compound
• Color and flavor additives

Correct Answer: Concentration of weak base and its pKa relative to gastric pH

Q14. Which antacid component is commonly used to reduce serum phosphate levels in patients with chronic kidney disease?

• Sodium bicarbonate
• Calcium carbonate
• Aluminum hydroxide
• Simethicone

Correct Answer: Aluminum hydroxide

Q15. Which antacid should be used with caution or avoided in a patient with pre-existing hypercalcemia?

• Magnesium hydroxide
• Aluminum hydroxide
• Sodium bicarbonate
• Calcium carbonate

Correct Answer: Calcium carbonate

Q16. Which antacid has the longest duration of action per dose among common oral antacids?

• Sodium bicarbonate
• Magnesium hydroxide
• Aluminum hydroxide
• Calcium carbonate

Correct Answer: Calcium carbonate

Q17. Antacid use can reduce the oral absorption of which drug class that requires acidic pH for dissolution?

• Weak bases like ketoconazole and itraconazole
• Beta-lactam antibiotics
• Insulin
• Low molecular weight heparins

Correct Answer: Weak bases like ketoconazole and itraconazole

Q18. Which antacid is most likely to cause metabolic alkalosis after systemic absorption or excessive use?

• Aluminum hydroxide
• Magnesium hydroxide
• Sodium bicarbonate
• Simethicone

Correct Answer: Sodium bicarbonate

Q19. Prolonged use of which antacid can lead to hypophosphatemia and osteomalacia due to phosphate binding?

• Magnesium hydroxide
• Calcium carbonate
• Aluminum hydroxide
• Sodium bicarbonate

Correct Answer: Aluminum hydroxide

Q20. Which antacid salt doubles as a calcium supplement and can contribute to calcium intake?

• Sodium bicarbonate
• Magnesium hydroxide
• Calcium carbonate
• Aluminum hydroxide

Correct Answer: Calcium carbonate

Q21. Maalox and Mylanta are examples of over-the-counter antacids that commonly contain which combination?

• Aluminum hydroxide and magnesium hydroxide
• Sodium bicarbonate and potassium chloride
• Calcium carbonate and simethicone only
• Aluminum phosphate and sildenafil

Correct Answer: Aluminum hydroxide and magnesium hydroxide

Q22. An overdose of magnesium-containing antacids can lead to which serious metabolic disturbance?

• Hypomagnesemia
• Hypermagnesemia with neuromuscular depression
• Hyperkalemia and arrhythmias
• Severe hyponatremia

Correct Answer: Hypermagnesemia with neuromuscular depression

Q23. The classic triad of milk-alkali syndrome includes which of the following?

• Hypermagnesemia, metabolic acidosis and osteosclerosis
• Hypercalcemia, metabolic alkalosis and renal insufficiency
• Hypocalcemia, metabolic acidosis and increased phosphate
• Hypernatremia, respiratory alkalosis and edema

Correct Answer: Hypercalcemia, metabolic alkalosis and renal insufficiency

Q24. Which over-the-counter antacid product typically contains calcium carbonate and magnesium hydroxide?

• Tums
• Rolaids
• Maalox
• Gaviscon (alginate formulation)

Correct Answer: Rolaids

Q25. Which antacid agent is available as an intravenous preparation for acute metabolic acidosis?

• Sodium bicarbonate
• Magnesium hydroxide
• Aluminum hydroxide
• Calcium carbonate

Correct Answer: Sodium bicarbonate

Q26. In severe renal impairment which antacid categories are generally recommended to avoid due to risk of toxic accumulation?

• Calcium and sodium salts only
• Aluminum and magnesium salts
• Simethicone and alginate
• Enteric-coated antacids only

Correct Answer: Aluminum and magnesium salts

Q27. At approximately what gastric pH does pepsin become largely inactive, reducing proteolytic damage?

• pH > 7
• pH > 4
• pH < 2
• pH 1-2

Correct Answer: pH > 4

Q28. Antacid therapy can decrease the oral absorption of which mineral supplement by raising gastric pH or forming insoluble complexes?

• Iron salts
• Vitamin B12
• Folic acid
• Vitamin C

Correct Answer: Iron salts

Q29. Reaction of sodium bicarbonate with gastric acid produces which gaseous byproduct that can cause belching?

• Ammonia
• Carbon dioxide
• Hydrogen sulfide
• Methane

Correct Answer: Carbon dioxide

Q30. How does alginate-antacid formulation reduce gastroesophageal reflux symptoms?

• By systemic inhibition of acid secretion
• By forming a buoyant gel raft that floats on gastric contents
• By chelating dietary fats
• By accelerating gastric emptying

Correct Answer: By forming a buoyant gel raft that floats on gastric contents

Q31. To minimize drug interactions, when should antacids generally be administered relative to most other oral medications?

• Simultaneously with other oral medications
• At least 2 hours before or after other oral medications
• Only at bedtime
• Only with meals

Correct Answer: At least 2 hours before or after other oral medications

Q32. Buffering capacity of an antacid is commonly expressed in which unit?

• mg/kg body weight
• mEq of HCl neutralized per gram of antacid
• IU per tablet
• mg of active ingredient per mL

Correct Answer: mEq of HCl neutralized per gram of antacid

Q33. Which antacid is classically associated with “acid rebound” after its neutralizing effect wears off?

• Sodium bicarbonate
• Aluminum hydroxide
• Magnesium hydroxide
• Calcium carbonate

Correct Answer: Calcium carbonate

Q34. The principal therapeutic rationale for combining different antacid salts in one product is to:

• Enhance systemic absorption of cations
• Maximize pH elevation indefinitely
• Balance adverse effects while preserving neutralization efficacy
• Reduce manufacturing costs

Correct Answer: Balance adverse effects while preserving neutralization efficacy

Q35. Which of the following antacid-related effects can alter urinary drug excretion by changing urine pH?

• Sodium bicarbonate increasing urinary pH and promoting excretion of weak acids
• Simethicone decreasing urinary pH
• Alginate increasing renal perfusion directly
• Calcium carbonate causing urinary alkalinization that traps basic drugs

Correct Answer: Sodium bicarbonate increasing urinary pH and promoting excretion of weak acids

Q36. Chronic aluminum accumulation from antacid use may cause which neurological complication in susceptible patients?

• Peripheral neuropathy only
• Encephalopathy and cognitive impairment
• Parkinsonism due to dopamine receptor blockade
• Migraine headaches exclusively

Correct Answer: Encephalopathy and cognitive impairment

Q37. Which antacid would most likely reduce the bioavailability of orally administered levothyroxine if taken concomitantly?

• Simethicone
• Aluminum- or calcium-containing antacids that bind levothyroxine
• Alginate alone
• Buffered saline

Correct Answer: Aluminum- or calcium-containing antacids that bind levothyroxine

Q38. Which property of an antacid is most important for rapid symptom relief in acute heartburn?

• High buffering capacity and rapid dissolution
• High systemic bioavailability
• Enteric coating to delay action
• High molecular weight

Correct Answer: High buffering capacity and rapid dissolution

Q39. A patient on ciprofloxacin should avoid taking an antacid at the same time because of what interaction?

• Antacid-induced increase in ciprofloxacin clearance
• Chelation of ciprofloxacin with divalent/trivalent cations reducing absorption
• Stimulation of CYP450 increasing ciprofloxacin metabolism
• Direct chemical degradation of ciprofloxacin by simethicone

Correct Answer: Chelation of ciprofloxacin with divalent/trivalent cations reducing absorption

Q40. Which of the following statements about antacids and H. pylori therapy is correct?

• Antacids eradicate H. pylori and replace antibiotics
• Antacids have no role in H. pylori eradication but may relieve dyspepsia
• Antacids increase H. pylori growth and should be avoided
• Antacids enhance the bactericidal activity of amoxicillin

Correct Answer: Antacids have no role in H. pylori eradication but may relieve dyspepsia

Q41. Which antacid combination is least likely to cause significant systemic electrolyte disturbance in patients with normal renal function?

• Large doses of sodium bicarbonate daily
• Moderate doses of aluminum-magnesium combination antacids
• High-dose calcium carbonate indefinitely
• Excess magnesium hydroxide in renal failure

Correct Answer: Moderate doses of aluminum-magnesium combination antacids

Q42. Which antacid component is used when the clinical goal includes phosphate binding in CKD patients but carries a risk of encephalopathy if accumulated?

• Calcium carbonate
• Aluminum hydroxide
• Magnesium hydroxide
• Sodium bicarbonate

Correct Answer: Aluminum hydroxide

Q43. Which antacid action can directly impair the absorption of vitamin B12 when used chronically?

• Chelation of B12 by aluminum ions
• Raising gastric pH and reducing cleavage of B12 from food proteins
• Simethicone binding intrinsic factor
• Alginate forming complexes with gastric lining cells

Correct Answer: Raising gastric pH and reducing cleavage of B12 from food proteins

Q44. For an immediate episode of severe heartburn in pregnancy, which over-the-counter antacid is commonly recommended as first-line due to safety profile?

• Aluminum-containing antacids in combined preparations
• Sodium bicarbonate regularly
• High-dose magnesium laxatives
• Systemic PPIs without safety data

Correct Answer: Aluminum-containing antacids in combined preparations

Q45. Which antacid(s) may decrease the absorption of oral itraconazole by raising gastric pH?

• Aluminum hydroxide only
• Any antacid that significantly raises gastric pH (e.g., bicarbonate-containing agents)
• Simethicone only
• Alginate alone

Correct Answer: Any antacid that significantly raises gastric pH (e.g., bicarbonate-containing agents)

Q46. In designing an antacid tablet, which formulation additive is often included to reduce gastric bloating and gas?

• Simethicone
• Aluminum hydroxide
• Sodium chloride
• Calcium carbonate

Correct Answer: Simethicone

Q47. Which antacid effect is useful for short-term symptomatic relief but may mask serious conditions like peptic ulcer perforation?

• Systemic phosphate binding
• Rapid neutralization of gastric acid and symptomatic relief
• Renal protective effects
• Enhancement of gastric motility

Correct Answer: Rapid neutralization of gastric acid and symptomatic relief

Q48. What is a common counseling point for patients taking oral dosage forms and antacids to avoid decreased drug absorption?

• Take antacids with all medications to enhance absorption
• Space antacid dosing at least 2 hours apart from other oral medications
• Stop antacids permanently when starting any chronic medication
• Crush enteric-coated tablets and take with antacid

Correct Answer: Space antacid dosing at least 2 hours apart from other oral medications

Q49. Which of the following antacid effects may worsen hypertension or edema in susceptible patients?

• Sodium load from certain antacid preparations
• Magnesium-induced vasodilation
• Calcium carbonate decreasing blood pressure
• Simethicone increasing intravascular volume

Correct Answer: Sodium load from certain antacid preparations

Q50. When evaluating an antacid product, which parameter best predicts its clinical effectiveness for neutralizing acid?

• Flavor and color
• Buffering capacity and neutralizing units per dose
• Tablet shape
• Manufacturer’s logo presence

Correct Answer: Buffering capacity and neutralizing units per dose

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