Antacids: Sodium bicarbonate* MCQs With Answer

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Antacids: Sodium bicarbonate MCQs With Answer

Sodium bicarbonate is a fast-acting antacid widely studied in B.Pharm courses for its acid-neutralizing chemistry, mechanism of action, pharmacokinetics, drug interactions, and adverse effects. This introduction covers key points: NaHCO3 neutralizes gastric HCl producing CO2 and water, has rapid onset but short duration, carries a significant sodium load, and can cause metabolic alkalosis or milk-alkali syndrome. Understanding dosing calculations (mEq/mmol), clinical uses (dyspepsia, temporary heartburn relief, IV use in acidosis), contraindications (severe renal failure, uncontrolled hypertension) and interactions with antibiotics and oral drugs is essential. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What is the chemical formula of sodium bicarbonate?

  • Na2CO3
  • NaHCO3
  • NaOH
  • NaCl

Correct Answer: NaHCO3

Q2. Which reaction occurs when sodium bicarbonate neutralizes gastric acid?

  • NaHCO3 + HCl → NaCl + H2O + CO2
  • NaHCO3 + HCl → NaCl + H2
  • NaHCO3 + HCl → NaOH + CO2
  • NaHCO3 + HCl → NaH + CO3

Correct Answer: NaHCO3 + HCl → NaCl + H2O + CO2

Q3. What is the primary pharmacological action of sodium bicarbonate as an antacid?

  • Inhibition of H+/K+ ATPase
  • Neutralization of gastric hydrochloric acid
  • Blockade of histamine H2 receptors
  • Increase of gastric motility

Correct Answer: Neutralization of gastric hydrochloric acid

Q4. Which property best describes the onset and duration of oral sodium bicarbonate antacid effect?

  • Slow onset, long duration
  • Rapid onset, short duration
  • Slow onset, short duration
  • Rapid onset, long duration

Correct Answer: Rapid onset, short duration

Q5. Sodium bicarbonate antacid can cause which systemic adverse effect if overused?

  • Metabolic acidosis
  • Metabolic alkalosis
  • Lactic acidosis
  • Respiratory acidosis

Correct Answer: Metabolic alkalosis

Q6. Which syndrome is classically associated with excessive intake of calcium and absorbable alkali like sodium bicarbonate?

  • Reye syndrome
  • Milk-alkali syndrome
  • Serotonin syndrome
  • Carcinoid syndrome

Correct Answer: Milk-alkali syndrome

Q7. How many milliequivalents (mEq) of bicarbonate are approximately present in 1 gram of NaHCO3? (Molar mass ~84 g/mol)

  • 1 mEq
  • 5.9 mEq
  • 11.9 mEq
  • 84 mEq

Correct Answer: 11.9 mEq

Q8. Which patients should use sodium bicarbonate with caution due to sodium load?

  • Patients with hypothyroidism
  • Patients with hypertension or heart failure
  • Patients with asthma
  • Patients with hyperlipidemia

Correct Answer: Patients with hypertension or heart failure

Q9. Which laboratory value might increase after sodium bicarbonate ingestion?

  • Serum potassium
  • Serum bicarbonate (HCO3-)
  • Serum chloride
  • Serum phosphate

Correct Answer: Serum bicarbonate (HCO3-)

Q10. Which route is commonly used for rapid systemic correction of severe metabolic acidosis with sodium bicarbonate?

  • Oral solution only
  • Intravenous infusion
  • Intramuscular injection
  • Inhalation nebulizer

Correct Answer: Intravenous infusion

Q11. Sodium bicarbonate increases gastric pH. This change can reduce absorption of which class of antifungal drugs?

  • Azoles that require acidic pH like ketoconazole
  • Echinocandins like caspofungin
  • Polyenes like amphotericin B
  • Terbinafine unaffected by pH

Correct Answer: Azoles that require acidic pH like ketoconazole

Q12. Which of the following is a common immediate gastrointestinal side effect of oral sodium bicarbonate?

  • Constipation
  • Belching and flatulence due to CO2 generation
  • Intestinal bleeding
  • Severe diarrhea

Correct Answer: Belching and flatulence due to CO2 generation

Q13. In renal failure, sodium bicarbonate use is generally:

  • Recommended without restrictions
  • Contraindicated entirely in all stages
  • Used with caution due to reduced bicarbonate excretion and sodium retention
  • Only used as an inhaled therapy

Correct Answer: Used with caution due to reduced bicarbonate excretion and sodium retention

Q14. Which equation approximates the bicarbonate deficit for IV therapy? (Simplified)

  • Bicarbonate deficit = (Measured HCO3- − Desired HCO3-) × weight (kg) × 0.3
  • Bicarbonate deficit = Weight (kg) / (Measured HCO3- × 0.3)
  • Bicarbonate deficit = Desired HCO3- × 0.1
  • Bicarbonate deficit = Serum Na+ × 0.6

Correct Answer: Bicarbonate deficit = (Measured HCO3- − Desired HCO3-) × weight (kg) × 0.3

Q15. Which is a major pharmacokinetic concern when sodium bicarbonate is coadministered with oral fluoroquinolones?

  • Enhanced hepatic metabolism of fluoroquinolones
  • Chelation with divalent cations
  • Increase in gastric motility reducing absorption time
  • pH-dependent ionization changes that can decrease absorption

Correct Answer: pH-dependent ionization changes that can decrease absorption

Q16. Sodium bicarbonate is classified as which type of antacid?

  • Non-absorbable antacid
  • Absorbable systemic antacid
  • H2 receptor antagonist
  • Proton pump inhibitor

Correct Answer: Absorbable systemic antacid

Q17. Which of the following best describes the buffering capacity of sodium bicarbonate in stomach?

  • It acts as a strong base and raises pH indefinitely
  • It provides limited buffering and is consumed rapidly by excess acid
  • It permanently neutralizes acid by forming insoluble salts
  • It lowers gastric pH further

Correct Answer: It provides limited buffering and is consumed rapidly by excess acid

Q18. Which patient population is particularly at risk for milk-alkali syndrome when using sodium bicarbonate?

  • Young athletes drinking only water
  • Patients consuming high calcium supplements and antacids
  • Patients with hyperthyroidism only
  • Patients using topical antacids

Correct Answer: Patients consuming high calcium supplements and antacids

Q19. Which ion is the primary contributor to fluid retention risk from sodium bicarbonate?

  • Potassium
  • Chloride
  • Sodium
  • Magnesium

Correct Answer: Sodium

Q20. Sodium bicarbonate may cause which change in serum potassium in the short term when administered IV?

  • Hyperkalemia due to cell lysis
  • Hypokalemia due to intracellular shift of potassium
  • No change in potassium concentration
  • Increased potassium absorption from gut

Correct Answer: Hypokalemia due to intracellular shift of potassium

Q21. Which medication interaction is most likely when sodium bicarbonate raises gastric pH?

  • Increased absorption of atazanavir
  • Decreased absorption of ketoconazole and itraconazole
  • Enhanced efficacy of bisphosphonates
  • No interactions with any oral drugs

Correct Answer: Decreased absorption of ketoconazole and itraconazole

Q22. What is the principal excretory organ responsible for eliminating excess bicarbonate?

  • Liver
  • Kidneys
  • Skin
  • Lungs

Correct Answer: Kidneys

Q23. CO2 generation from sodium bicarbonate neutralization can aggravate which condition in patients with severe COPD?

  • Hypocapnia
  • Worsening hypercapnia and respiratory failure
  • Bronchospasm relief
  • Improved oxygenation

Correct Answer: Worsening hypercapnia and respiratory failure

Q24. Which parameter is directly neutralized by one mole of bicarbonate in solution?

  • One mole of hydroxide
  • One mole of hydrogen ion (H+)
  • Two moles of hydrogen ion
  • No direct neutralization occurs

Correct Answer: One mole of hydrogen ion (H+)

Q25. How does sodium bicarbonate affect the urinary pH after oral or IV administration?

  • Decreases urinary pH making it more acidic
  • Increases urinary pH making it more alkaline
  • No change in urinary pH
  • Causes cyclic fluctuations only

Correct Answer: Increases urinary pH making it more alkaline

Q26. Which clinical use of sodium bicarbonate is routinely taught in emergency medicine?

  • Treatment of anaphylaxis
  • Management of severe metabolic acidosis with hemodynamic compromise
  • First-line therapy for peptic ulcer disease long term
  • Routine use for GERD maintenance therapy

Correct Answer: Management of severe metabolic acidosis with hemodynamic compromise

Q27. What is a key difference between sodium bicarbonate and non-absorbable antacids (e.g., magnesium hydroxide)?

  • Sodium bicarbonate is non-systemic; magnesium hydroxide is systemic
  • Sodium bicarbonate is absorbed systemically and contributes to systemic alkalosis; magnesium hydroxide is largely non-absorbable
  • Both are equally non-absorbable
  • Magnesium hydroxide causes more systemic sodium retention

Correct Answer: Sodium bicarbonate is absorbed systemically and contributes to systemic alkalosis; magnesium hydroxide is largely non-absorbable

Q28. Which monitoring parameter is most important when IV sodium bicarbonate is given for metabolic acidosis?

  • Serum transaminases only
  • Arterial blood gas and serum electrolytes
  • Serum lipase
  • Pulse oximetry alone

Correct Answer: Arterial blood gas and serum electrolytes

Q29. Oral sodium bicarbonate tablets are typically buffered with which gas released on reaction with acid?

  • Oxygen
  • Nitrogen
  • Carbon dioxide
  • Hydrogen sulfide

Correct Answer: Carbon dioxide

Q30. Which statement about sodium bicarbonate and absorption of weak acids is correct?

  • Raising gastric pH improves absorption of all weak acids
  • Raising gastric pH can increase ionization of weak acids and reduce their passive absorption in stomach
  • Sodium bicarbonate directly chemically binds weak acids making them more absorbable
  • Gastric pH has no effect on weak acid absorption

Correct Answer: Raising gastric pH can increase ionization of weak acids and reduce their passive absorption in stomach

Q31. Sodium bicarbonate is often avoided with which oral medication class due to chelation or pH effects?

  • Benzodiazepines
  • Tetracyclines and some fluoroquinolones
  • SSRIs
  • Insulin

Correct Answer: Tetracyclines and some fluoroquinolones

Q32. In overdose or excessive use, sodium bicarbonate can lead to which electrolyte abnormality due to renal compensation?

  • Hypermagnesemia
  • Hypernatremia
  • Hyponatremia
  • Hyperphosphatemia

Correct Answer: Hypernatremia

Q33. Which form of sodium bicarbonate is commonly used in effervescent antacid preparations?

  • Anhydrous NaHCO3 powder
  • Buffered tablets combining NaHCO3 with citric acid to release CO2
  • Injectable sodium bicarbonate crystals
  • Topical NaHCO3 gel

Correct Answer: Buffered tablets combining NaHCO3 with citric acid to release CO2

Q34. Which physiochemical property of NaHCO3 leads to rapid neutralization of gastric acid?

  • Its strong acid nature
  • Its solubility and ability to dissociate into Na+ and HCO3-
  • Its protein-binding capacity
  • Its lipophilicity

Correct Answer: Its solubility and ability to dissociate into Na+ and HCO3-

Q35. For B.Pharm students calculating moles: how many mmol of NaHCO3 are in 2 grams? (Molar mass ≈84 g/mol)

  • Approximately 2 mmol
  • Approximately 23.8 mmol
  • Approximately 11.9 mmol
  • Approximately 84 mmol

Correct Answer: Approximately 23.8 mmol

Q36. What is the main reason sodium bicarbonate is not preferred for chronic management of peptic ulcer disease?

  • Ineffective at neutralizing acid
  • Short duration of action and systemic side effects with chronic use
  • It causes severe gastritis on long-term use
  • It permanently damages parietal cells

Correct Answer: Short duration of action and systemic side effects with chronic use

Q37. Which effect on gastric pH is expected immediately after taking oral sodium bicarbonate?

  • Gastric pH decreases to become more acidic
  • Gastric pH rises (becomes less acidic)
  • Gastric pH becomes neutral and stays indefinitely
  • Gastric pH is unchanged

Correct Answer: Gastric pH rises (becomes less acidic)

Q38. Which of the following is a contraindication to rapid IV bolus of concentrated sodium bicarbonate?

  • Hypotension only
  • Known metabolic alkalosis or hypernatremia
  • Hypokalemia only
  • Mild dehydration only

Correct Answer: Known metabolic alkalosis or hypernatremia

Q39. Which effect on gastric emptying is associated with gas generation from sodium bicarbonate?

  • Decreased gastric emptying due to increased intragastric pressure
  • Increased gastric emptying by stimulating motility always
  • No possible effect on gastric emptying
  • Guaranteed pyloric obstruction

Correct Answer: Decreased gastric emptying due to increased intragastric pressure

Q40. In the context of drug formulation, why might sodium bicarbonate be included in effervescent analgesic tablets?

  • To increase bitterness
  • To produce CO2 and enhance dissolution and palatability
  • To decrease tablet disintegration
  • To neutralize active drug

Correct Answer: To produce CO2 and enhance dissolution and palatability

Q41. How does sodium bicarbonate affect the oral bioavailability of atazanavir?

  • It increases bioavailability by acidifying stomach
  • It reduces bioavailability by increasing gastric pH
  • It has no effect
  • It forms a stable complex enhancing absorption

Correct Answer: It reduces bioavailability by increasing gastric pH

Q42. What is the expected impact of sodium bicarbonate on serum chloride in metabolic alkalosis caused by bicarbonate excess?

  • Serum chloride typically rises markedly
  • Serum chloride typically falls (hypochloremia)
  • Serum chloride is unaffected
  • Serum chloride is replaced by phosphate

Correct Answer: Serum chloride typically falls (hypochloremia)

Q43. Which of the following is an important counseling point for patients taking sodium bicarbonate tablets?

  • Take with large amounts of milk to enhance effect
  • Avoid chronic excessive use because of sodium load and alkalosis risk
  • It can be used daily for months without monitoring
  • It has no interactions with prescription drugs

Correct Answer: Avoid chronic excessive use because of sodium load and alkalosis risk

Q44. Which physiological buffer system is closely linked with bicarbonate in acid-base balance?

  • Phosphate buffer only
  • Hemoglobin buffer only
  • Carbonic acid–bicarbonate buffer system involving CO2 and H2CO3
  • Ammonia buffer only

Correct Answer: Carbonic acid–bicarbonate buffer system involving CO2 and H2CO3

Q45. Which of the following is TRUE about sodium bicarbonate tablets given to infants?

  • They are the preferred chronic antacid in infants
  • They should be used cautiously due to risk of systemic alkalosis and sodium overload
  • They have no systemic absorption in infants
  • They prevent infantile colic safely

Correct Answer: They should be used cautiously due to risk of systemic alkalosis and sodium overload

Q46. Which clinical scenario would most likely warrant temporary use of oral sodium bicarbonate?

  • Long-term maintenance of GERD
  • Acute, intermittent heartburn requiring rapid relief
  • Prophylaxis of peptic ulcer bleeding indefinitely
  • As a primary therapy for H. pylori eradication

Correct Answer: Acute, intermittent heartburn requiring rapid relief

Q47. Which of these best explains why sodium bicarbonate may reduce gastric absorption of iron supplements?

  • Ionic competition with sodium prevents iron uptake
  • Increased gastric pH reduces solubility of ferrous iron and thus absorption
  • Sodium bicarbonate chemically converts iron to metallic form
  • No effect; iron absorption increases with higher pH

Correct Answer: Increased gastric pH reduces solubility of ferrous iron and thus absorption

Q48. How does sodium bicarbonate affect the efficacy of orally administered weakly basic drugs that require acidic environment for dissolution?

  • Enhances dissolution and absorption
  • Decreases dissolution and absorption due to elevated pH
  • Has no impact on dissolution
  • Inactivates the drug chemically always

Correct Answer: Decreases dissolution and absorption due to elevated pH

Q49. Which monitoring is most appropriate for a patient on chronic high-dose oral sodium bicarbonate?

  • Routine liver ultrasound
  • Periodic serum electrolytes, bicarbonate, and renal function tests
  • Monthly chest X-ray
  • No monitoring required

Correct Answer: Periodic serum electrolytes, bicarbonate, and renal function tests

Q50. Which statement about dosing equivalence is correct? Approximately how many mEq of bicarbonate correspond to a 1-gram dose of sodium bicarbonate?

  • 1 g ≈ 84 mEq
  • 1 g ≈ 1 mEq
  • 1 g ≈ 11.9 mEq
  • 1 g ≈ 100 mEq

Correct Answer: 1 g ≈ 11.9 mEq

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