Sulfonylureas – Tolbutamide MCQs With Answer

Sulfonylureas – Tolbutamide MCQs With Answer

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Sulfonylureas – Tolbutamide MCQs With Answer

Sulfonylureas are oral hypoglycemic agents used in Type 2 diabetes; tolbutamide is a classic first‑generation sulfonylurea. This concise, keyword‑rich introduction covers mechanism of action (ATP‑sensitive K+ or KATP channel blockade), pharmacokinetics (hepatic metabolism, protein binding, short duration), clinical uses, adverse effects (hypoglycemia, weight gain), drug interactions (sulfonamides, warfarin, alcohol), and antidotes (dextrose, octreotide). B.Pharm students will benefit from focused facts on receptor subunits, therapeutic implications, monitoring, and safety. The following questions emphasize pharmacology, toxicology, and patient care relevant to tolbutamide and sulfonylureas. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which of the following best describes the primary mechanism of action of tolbutamide?

  • Activation of insulin receptor tyrosine kinase
  • Inhibition of hepatic gluconeogenesis enzymes
  • Closure of pancreatic beta‑cell ATP‑sensitive K+ channels leading to insulin release
  • Stimulation of incretin release from the gut

Correct Answer: Closure of pancreatic beta‑cell ATP‑sensitive K+ channels leading to insulin release

Q2. Tolbutamide belongs to which generation of sulfonylureas?

  • Zero generation
  • First generation
  • Second generation
  • Third generation

Correct Answer: First generation

Q3. Which pancreatic KATP channel subunit is primarily involved in binding sulfonylureas?

  • SUR1 (sulfonylurea receptor 1)
  • SUR2A
  • Kir6.2 only
  • GLUT2 transporter

Correct Answer: SUR1 (sulfonylurea receptor 1)

Q4. Which statement about tolbutamide pharmacokinetics is true?

  • It is primarily excreted unchanged in urine
  • It undergoes extensive hepatic metabolism to inactive metabolites
  • It has a very long half‑life exceeding 48 hours
  • It is minimally bound to plasma proteins

Correct Answer: It undergoes extensive hepatic metabolism to inactive metabolites

Q5. Which adverse effect is most clinically significant with tolbutamide therapy?

  • Hypoglycemia
  • Hyperuricemia
  • Hypokalemia
  • Respiratory depression

Correct Answer: Hypoglycemia

Q6. Which of the following drug interactions increases the risk of sulfonylurea‑induced hypoglycemia?

  • Co‑administration with rifampicin
  • Co‑administration with aminoglycosides
  • Co‑administration with sulfonamide antibiotics
  • Co‑administration with metoclopramide

Correct Answer: Co‑administration with sulfonamide antibiotics

Q7. Which clinical scenario is a contraindication for tolbutamide use?

  • Newly diagnosed Type 2 diabetic adult with obesity
  • Gestational diabetes in the first trimester
  • Stable elderly patient with preserved renal function
  • Type 2 diabetic patient refusing insulin

Correct Answer: Gestational diabetes in the first trimester

Q8. Which treatment is most appropriate for persistent sulfonylurea‑induced hypoglycemia after dextrose bolus?

  • Intravenous glucocorticoids
  • Oral glucose only
  • Intramuscular epinephrine
  • Subcutaneous or intravenous octreotide

Correct Answer: Subcutaneous or intravenous octreotide

Q9. Which property differentiates first‑generation from second‑generation sulfonylureas?

  • Second‑generation agents have longer half‑lives than first‑generation always
  • Second‑generation agents are generally more potent and require lower doses
  • First‑generation agents are more selective for SUR2 receptors
  • First‑generation agents increase incretin secretion

Correct Answer: Second‑generation agents are generally more potent and require lower doses

Q10. Tolbutamide’s tendency to cause a disulfiram‑like reaction is associated with co‑consumption of which substance?

  • Grapefruit juice
  • Acetaminophen
  • Ethanol (alcohol)
  • Caffeine

Correct Answer: Ethanol (alcohol)

Q11. Which effect on body weight is commonly seen with sulfonylurea therapy like tolbutamide?

  • Significant weight loss
  • Weight neutrality
  • Weight gain
  • Fluid‑only weight loss

Correct Answer: Weight gain

Q12. What is the primary route of elimination for tolbutamide metabolites?

  • Biliary excretion of unchanged drug
  • Renal excretion of polar metabolites
  • Exhalation via lungs
  • Sequestration in adipose tissue

Correct Answer: Renal excretion of polar metabolites

Q13. Which monitoring parameter is most important when initiating tolbutamide therapy?

  • Serum creatinine only
  • Fasting plasma glucose and hypoglycemia signs
  • Liver biopsy
  • Serum potassium

Correct Answer: Fasting plasma glucose and hypoglycemia signs

Q14. Which organ impairment requires dose adjustment or caution with tolbutamide?

  • Hepatic impairment
  • Acute otitis media
  • Localized skin infection
  • Peripheral neuropathy without renal issues

Correct Answer: Hepatic impairment

Q15. How does tolbutamide affect insulin secretion kinetics?

  • It increases insulin secretion by mobilizing stored insulin and enhancing rapid first‑phase release
  • It exclusively increases proinsulin synthesis without release
  • It decreases basal insulin and only raises incretin activity
  • It prevents insulin release by opening K+ channels

Correct Answer: It increases insulin secretion by mobilizing stored insulin and enhancing rapid first‑phase release

Q16. Which patient population is at highest risk for prolonged hypoglycemia with tolbutamide?

  • Young adults with normal renal and hepatic function
  • Elderly patients with renal or hepatic impairment
  • Patients on high‑protein diets only
  • Patients with controlled hypertension

Correct Answer: Elderly patients with renal or hepatic impairment

Q17. Which structural moiety is essential for sulfonylurea activity?

  • Beta‑lactam ring
  • Sulfonylurea group (–SO2–NH–CO–)
  • Quinolone nucleus
  • Benzodiazepine ring

Correct Answer: Sulfonylurea group (–SO2–NH–CO–)

Q18. Which laboratory pattern might be seen during severe sulfonylurea overdose?

  • Hyperglycemia with ketonemia
  • Hypoglycemia with suppressed C‑peptide
  • Hypoglycemia with elevated insulin and elevated C‑peptide
  • Normal glucose with elevated glucagon

Correct Answer: Hypoglycemia with elevated insulin and elevated C‑peptide

Q19. Which statement about tolbutamide and renal impairment is correct?

  • Tolbutamide is safe in end‑stage renal disease without dose change
  • Active metabolites may accumulate in renal failure increasing hypoglycemia risk
  • Renal impairment enhances tolbutamide hepatic clearance
  • Tolbutamide is eliminated by dialysis efficiently

Correct Answer: Active metabolites may accumulate in renal failure increasing hypoglycemia risk

Q20. Which clinical advantage do meglitinides (e.g., repaglinide) have over tolbutamide?

  • Longer duration of action for once‑daily dosing
  • Greater risk of delayed hypoglycemia
  • Shorter onset and shorter duration, reducing postprandial hypoglycemia risk
  • No interaction with CYP enzymes

Correct Answer: Shorter onset and shorter duration, reducing postprandial hypoglycemia risk

Q21. Which effect on lipid profile is associated with sulfonylurea therapy historically?

  • Marked reduction in LDL and triglycerides
  • No consistent favorable effect; neutral to variable changes
  • Consistent increase in HDL only
  • Immediate severe hypertriglyceridemia

Correct Answer: No consistent favorable effect; neutral to variable changes

Q22. Which counseling point is most important for patients starting tolbutamide?

  • Stop the drug if you feel slightly tired
  • Always carry a source of fast‑acting carbohydrate to treat hypoglycemia
  • Do not monitor blood glucose at home
  • Increase alcohol intake to prevent hypoglycemia

Correct Answer: Always carry a source of fast‑acting carbohydrate to treat hypoglycemia

Q23. Which hepatic enzyme system metabolizes many sulfonylureas including tolbutamide?

  • Cytosolic aldehyde oxidase only
  • Cytochrome P450 mixed‑function oxidases
  • Monoamine oxidase (MAO)
  • Glucose‑6‑phosphatase

Correct Answer: Cytochrome P450 mixed‑function oxidases

Q24. Which symptom profile is most typical of severe hypoglycemia from tolbutamide?

  • Polyuria and polydipsia without neuroglycopenic signs
  • Tremor, sweating, confusion, seizures, and possible coma
  • Persistent fever and rigors
  • Painless jaundice

Correct Answer: Tremor, sweating, confusion, seizures, and possible coma

Q25. Which laboratory test helps distinguish exogenous insulin overdose from sulfonylurea‑induced hypoglycemia?

  • Serum C‑peptide level
  • Serum sodium level
  • Serum alkaline phosphatase
  • Urine ketone only

Correct Answer: Serum C‑peptide level

Q26. Which adverse hepatic reaction has been reported with tolbutamide?

  • Cholestatic or hepatocellular liver injury (rare)
  • Immediate acute hepatic necrosis in all patients
  • Viral hepatitis due to immunosuppression
  • Renal tubular acidosis

Correct Answer: Cholestatic or hepatocellular liver injury (rare)

Q27. Which pharmacodynamic property explains why tolbutamide can cause hypoglycemia even if a meal is missed?

  • It increases renal glucose reabsorption
  • It stimulates sustained insulin release from pancreatic beta cells independent of current glucose levels
  • It blocks glucagon action permanently
  • It causes glycogenolysis

Correct Answer: It stimulates sustained insulin release from pancreatic beta cells independent of current glucose levels

Q28. Which one of the following is a pharmacotherapeutic reason tolbutamide is less commonly used today?

  • High cost compared with newer agents
  • Lower potency, shorter duration, and higher hypoglycemia risk in some patients compared with newer agents
  • Inability to lower blood glucose at all
  • Unavailability of oral formulations

Correct Answer: Lower potency, shorter duration, and higher hypoglycemia risk in some patients compared with newer agents

Q29. Which statement about secondary failure to sulfonylureas is correct?

  • Secondary failure is impossible with tolbutamide
  • Beta‑cell exhaustion or progressive disease can lead to loss of response over time
  • Secondary failure indicates noncompliance only
  • Switching to another sulfonylurea always restores efficacy permanently

Correct Answer: Beta‑cell exhaustion or progressive disease can lead to loss of response over time

Q30. Which statement about tolbutamide dosing is accurate?

  • It is typically given as a single very large dose weekly
  • It is dosed cautiously and often multiple times daily due to short duration of action
  • Dosing does not need adjustment for age or hepatic function
  • It is only available as an intravenous formulation

Correct Answer: It is dosed cautiously and often multiple times daily due to short duration of action

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