Introduction: Diltiazem hydrochloride MCQs With Answer provide B. Pharm students a focused review of this benzothiazepine calcium channel blocker. These questions cover mechanism of action, pharmacodynamics, pharmacokinetics (bioavailability, hepatic metabolism via CYP3A4), formulations (immediate and extended‑release, IV), therapeutic uses (hypertension, angina, atrial fibrillation rate control), dosing considerations, adverse effects (peripheral edema, bradycardia, gingival hyperplasia), drug interactions (grapefruit, statins, beta‑blockers), monitoring and overdose management. This concise, exam‑oriented set deepens understanding beyond basics and sharpens clinical‑pharmaceutical reasoning. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. Which pharmacological class does diltiazem hydrochloride belong to?
- Benzothiazepine calcium channel blocker
- Dihydropyridine calcium channel blocker
- Phenylalkylamine calcium channel blocker
- Beta‑adrenergic blocker
Correct Answer: Benzothiazepine calcium channel blocker
Q2. What is the primary mechanism of action of diltiazem?
- Blocks L‑type calcium channels, reducing AV nodal conduction and myocardial contractility
- Inhibits ACE, decreasing angiotensin II formation
- Stimulates beta‑2 receptors to cause vasodilation
- Blocks sodium channels in ventricular myocytes
Correct Answer: Blocks L‑type calcium channels, reducing AV nodal conduction and myocardial contractility
Q3. Which of the following is a major clinical indication for diltiazem?
- Hypertension, chronic stable angina, and control of ventricular rate in atrial fibrillation
- Heart block requiring pacemaker implantation
- Acute myocardial rupture
- Type 1 diabetes mellitus
Correct Answer: Hypertension, chronic stable angina, and control of ventricular rate in atrial fibrillation
Q4. Is an intravenous formulation of diltiazem available for clinical use?
- Yes, intravenous formulation is available for rapid ventricular rate control
- No, diltiazem is only available as an oral tablet
- Only subcutaneous injections are available
- Only topical cream formulations exist
Correct Answer: Yes, intravenous formulation is available for rapid ventricular rate control
Q5. Which hepatic enzyme system primarily metabolizes diltiazem?
- CYP3A4
- CYP2D6
- CYP1A2
- CYP2C9
Correct Answer: CYP3A4
Q6. What is the most common adverse effect associated with diltiazem therapy?
- Peripheral edema
- Neutropenia
- Hypoglycemia
- Tendon rupture
Correct Answer: Peripheral edema
Q7. In which situation is diltiazem contraindicated?
- Second‑ or third‑degree AV block without a pacemaker
- Mild seasonal allergic rhinitis
- Asymptomatic hyperlipidemia
- Uncomplicated migraine prophylaxis
Correct Answer: Second‑ or third‑degree AV block without a pacemaker
Q8. Which of the following drug combinations with diltiazem can result in severe bradycardia or AV block?
- Concomitant beta‑blocker therapy
- Concurrent inhaled salbutamol
- Co‑administration with levothyroxine
- Topical steroid use
Correct Answer: Concomitant beta‑blocker therapy
Q9. Which dietary substance significantly increases plasma concentrations of diltiazem?
- Grapefruit juice
- Green tea
- High‑fiber meals
- Probiotic yogurt
Correct Answer: Grapefruit juice
Q10. Which uncommon adverse effect of diltiazem is important for dental monitoring?
- Gingival hyperplasia
- Tooth discoloration
- Pulp necrosis
- Enamel hypoplasia
Correct Answer: Gingival hyperplasia
Q11. Compared to verapamil and dihydropyridine CCBs, diltiazem is best described as:
- Intermediate in cardiac depressant effects between verapamil and dihydropyridines
- Purely vascular with no cardiac effects
- More potent negative inotrope than verapamil
- Identical in effect to nifedipine
Correct Answer: Intermediate in cardiac depressant effects between verapamil and dihydropyridines
Q12. What is the approximate elimination half‑life of immediate‑release diltiazem in healthy adults?
- Approximately 3–4.5 hours
- Less than 30 minutes
- 24–36 hours
- 100–120 hours
Correct Answer: Approximately 3–4.5 hours
Q13. What is the oral bioavailability of diltiazem roughly attributed to first‑pass metabolism?
- About 40% due to significant hepatic first‑pass metabolism
- Nearly 100% with no first‑pass effect
- Less than 5% because of poor absorption
- About 80% with minimal metabolism
Correct Answer: About 40% due to significant hepatic first‑pass metabolism
Q14. What is the approximate plasma protein binding of diltiazem?
- Approximately 70–80% protein bound
- Less than 10% protein bound
- Over 99% protein bound
- Not protein bound at all
Correct Answer: Approximately 70–80% protein bound
Q15. Does diltiazem have active metabolites that contribute to its pharmacological effect?
- Yes, desacetyl‑diltiazem is an active metabolite with similar activity
- No, it has only inactive metabolites
- Only renal metabolites are active
- Metabolites act as beta‑blockers
Correct Answer: Yes, desacetyl‑diltiazem is an active metabolite with similar activity
Q16. Which parameters should be routinely monitored after initiating diltiazem therapy?
- Heart rate and blood pressure
- Serum amylase only
- Pulmonary function tests weekly
- Serum potassium daily
Correct Answer: Heart rate and blood pressure
Q17. Regarding use in pregnancy, which statement is most appropriate for diltiazem?
- Use only if potential benefit justifies potential risk to the fetus (risk‑benefit assessment)
- Contraindicated in all trimesters without exception
- Safe and recommended as first‑line antihypertensive in pregnancy
- Indicated for routine use in gestational diabetes
Correct Answer: Use only if potential benefit justifies potential risk to the fetus (risk‑benefit assessment)
Q18. How should dosing be adjusted in significant hepatic impairment?
- Reduce dose or increase dosing interval due to impaired metabolism
- No adjustment is required because it is renally cleared
- Double the dose to overcome hepatic inefficiency
- Switch to intravenous dosing only
Correct Answer: Reduce dose or increase dosing interval due to impaired metabolism
Q19. What is the main pharmacokinetic advantage of extended‑release diltiazem formulations?
- Smoother plasma concentrations and improved adherence with once‑daily dosing
- Complete avoidance of hepatic metabolism
- Instant elimination to prevent side effects
- Greater protein binding to reduce free drug
Correct Answer: Smoother plasma concentrations and improved adherence with once‑daily dosing
Q20. On the ECG, what change is commonly associated with diltiazem therapy?
- Prolongation of the PR interval
- Marked QT interval prolongation only
- Widening of the QRS complex exclusively
- Peaked T waves
Correct Answer: Prolongation of the PR interval
Q21. Co‑administration of diltiazem with which statin increases risk of myopathy due to CYP3A4 interaction?
- Simvastatin
- Pravastatin
- Rosuvastatin
- Fluvastatin
Correct Answer: Simvastatin
Q22. Is diltiazem effective in treating vasospastic (Prinzmetal’s) angina?
- Yes, it relaxes coronary smooth muscle and is effective in vasospastic angina
- No, it worsens coronary vasospasm
- Only nitrates are effective for vasospastic angina
- It is contraindicated in all forms of angina
Correct Answer: Yes, it relaxes coronary smooth muscle and is effective in vasospastic angina
Q23. Which ion channel subtype is the primary target of diltiazem?
- L‑type calcium channels
- T‑type calcium channels
- Sodium channels (fast type)
- BK potassium channels
Correct Answer: L‑type calcium channels
Q24. In severe diltiazem overdose, which initial therapies are commonly recommended?
- IV calcium, high‑dose insulin with glucose, and vasopressors as needed
- Immediate oral activated charcoal only
- Loop diuretics and beta‑agonists only
- Subcutaneous epinephrine as first line
Correct Answer: IV calcium, high‑dose insulin with glucose, and vasopressors as needed
Q25. Which of the following is a commonly known brand name for diltiazem?
- Cardizem
- Lopressor
- Zocor
- Plavix
Correct Answer: Cardizem
Q26. Compared with verapamil, diltiazem causes constipation:
- Less frequently than verapamil
- More frequently than verapamil
- Never causes constipation
- Only when given intravenously
Correct Answer: Less frequently than verapamil
Q27. Which cardiac effect is expected with therapeutic doses of diltiazem?
- Decrease in AV nodal conduction and possible bradycardia
- Marked increase in heart rate (tachycardia)
- Immediate ventricular fibrillation risk in all patients
- Complete insensitivity of the AV node
Correct Answer: Decrease in AV nodal conduction and possible bradycardia
Q28. Which formulation of diltiazem is best suited for once‑daily dosing?
- Extended‑release (CD/XR) formulation
- Immediate‑release every 2 hours
- Topical ointment
- Intramuscular depot injection
Correct Answer: Extended‑release (CD/XR) formulation
Q29. How does diltiazem affect digoxin when co‑administered?
- Diltiazem can increase digoxin levels by reducing its clearance
- Diltiazem markedly reduces digoxin serum concentration
- There is no interaction between diltiazem and digoxin
- Diltiazem converts digoxin into inactive metabolites
Correct Answer: Diltiazem can increase digoxin levels by reducing its clearance
Q30. Why should diltiazem be used with caution in patients with heart failure?
- Because it has negative inotropic effects and may worsen heart failure
- Because it causes severe volume depletion only
- Because it always causes myocardial infarction in heart failure
- Because it increases cardiac contractility excessively
Correct Answer: Because it has negative inotropic effects and may worsen heart failure
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