Lorcainide hydrochloride MCQs With Answer

Lorcainide hydrochloride MCQs With Answer

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Lorcainide hydrochloride MCQs With Answer
Lorcainide hydrochloride is a Class IC antiarrhythmic frequently studied by B. Pharm students for its potent sodium-channel blocking effects, use‑dependence, and risk of proarrhythmia. This focused introduction covers mechanism of action, pharmacology, pharmacokinetics, therapeutic indications, adverse effects, drug interactions, and monitoring parameters relevant to clinical and regulatory pharmacy practice. Understanding lorcainide’s impact on phase‑0 depolarization, QRS widening, contraindications (especially in structural heart disease), and safety considerations helps students master rational drug use and exam-style questions in pharmacology. Key terms: Lorcainide hydrochloride, Class IC, sodium channel blocker, QRS widening, proarrhythmia, pharmacokinetics, adverse effects.
‘Now let’s test your knowledge with 30 MCQs on this topic.’

Q1. What is the Vaughan-Williams classification of lorcainide hydrochloride?

  • Class IA antiarrhythmic agent
  • Class IB antiarrhythmic agent
  • Class IC antiarrhythmic agent
  • Class III antiarrhythmic agent

Correct Answer: Class IC antiarrhythmic agent

Q2. Which ion channel is the primary target of lorcainide hydrochloride?

  • Slow calcium (L-type) channels
  • Fast sodium channels
  • Delayed rectifier potassium channels
  • Funny (If) pacemaker channels

Correct Answer: Fast sodium channels

Q3. The principal electrophysiological effect of lorcainide on the cardiac action potential is:

  • Prolongation of phase 3 repolarization
  • Increase in phase 4 automaticity
  • Marked reduction of phase 0 upstroke velocity (Vmax)
  • Selective shortening of action potential duration

Correct Answer: Marked reduction of phase 0 upstroke velocity (Vmax)

Q4. On a surface ECG, lorcainide most characteristically causes which change?

  • Prolonged QT interval without QRS change
  • QRS complex widening
  • PR interval shortening
  • T wave inversion only

Correct Answer: QRS complex widening

Q5. Class IC antiarrhythmics like lorcainide are described as “use‑dependent.” What does this mean?

  • They bind more strongly at lower heart rates
  • They produce effect only with continuous infusion
  • They show increased sodium-channel block at higher heart rates
  • They are active only during sleep

Correct Answer: They show increased sodium-channel block at higher heart rates

Q6. The primary clinical indication for lorcainide hydrochloride is:

  • Hypertension management
  • Treatment of ventricular tachyarrhythmias
  • Rate control in atrial fibrillation as first-line therapy
  • Acute myocardial ischemia pain relief

Correct Answer: Treatment of ventricular tachyarrhythmias

Q7. Lorcainide is contraindicated in patients with which condition due to increased mortality risk shown in clinical trials?

  • Isolated supraventricular tachycardia without heart disease
  • Recent myocardial infarction or structural heart disease
  • Well-controlled hypertension
  • Mild seasonal allergies

Correct Answer: Recent myocardial infarction or structural heart disease

Q8. Which major safety concern is associated with lorcainide and other Class IC agents?

  • Severe hepatic necrosis as a common adverse effect
  • High risk of proarrhythmia, including new or worsened ventricular arrhythmias
  • Guaranteed prevention of sudden cardiac death in post‑MI patients
  • Complete lack of drug interactions

Correct Answer: High risk of proarrhythmia, including new or worsened ventricular arrhythmias

Q9. Which monitoring parameter is essential after initiating lorcainide therapy?

  • Serial chest X‑rays
  • ECG monitoring with attention to QRS duration
  • Daily complete blood counts only
  • Continuous pulse oximetry exclusively

Correct Answer: ECG monitoring with attention to QRS duration

Q10. The hydrochloride salt form of lorcainide primarily improves which pharmaceutical property?

  • Color and taste without affecting solubility
  • Solubility and stability for oral formulation
  • Ability to cross the blood-brain barrier selectively
  • Intrinsic pharmacological potency

Correct Answer: Solubility and stability for oral formulation

Q11. Which statement best describes lorcainide’s effect on action potential duration (APD) in ventricular myocardium?

  • Marked prolongation of APD similar to Class III agents
  • Marked shortening of APD in all cardiac tissues
  • Minimal effect on APD in ventricular tissue
  • Complete abolition of repolarization

Correct Answer: Minimal effect on APD in ventricular tissue

Q12. Which adverse effect is commonly reported with lorcainide therapy?

  • Renal stone formation as most common
  • Dizziness and CNS disturbances
  • High-grade proteinuria in most patients
  • Excessive hair growth in all patients

Correct Answer: Dizziness and CNS disturbances

Q13. Co-administration of lorcainide with which drug class requires caution due to additive conduction slowing?

  • Loop diuretics
  • Beta‑adrenergic blockers
  • Topical antifungals
  • Oral contraceptives

Correct Answer: Beta‑adrenergic blockers

Q14. The mechanism by which lorcainide may precipitate re-entrant ventricular arrhythmias is primarily due to:

  • Excessive potassium channel blockade only
  • Slowed conduction facilitating re‑entry circuits
  • Immediate increase in myocardial oxygen demand
  • Direct stimulation of pacemaker automaticity

Correct Answer: Slowed conduction facilitating re‑entry circuits

Q15. Before initiating lorcainide therapy, the most appropriate baseline assessment includes:

  • Complete allergy testing panel
  • Baseline ECG and assessment for structural heart disease
  • Baseline pulmonary function tests only
  • Routine bone density scan

Correct Answer: Baseline ECG and assessment for structural heart disease

Q16. Which pharmacokinetic factor is most important to consider with lorcainide in clinical use?

  • It is eliminated unchanged in feces only
  • It has a narrow therapeutic index and may accumulate, requiring monitoring
  • It does not interact with hepatic enzymes
  • It is instantly inactivated by gastric acid so oral dosing is ineffective

Correct Answer: It has a narrow therapeutic index and may accumulate, requiring monitoring

Q17. Which of the following best describes lorcainide’s selectivity within the heart?

  • Preferential action on AV nodal slow channels
  • Marked action on His-Purkinje system and ventricular myocardium
  • Exclusive action on atrial tissue only
  • Only vascular smooth muscle effects

Correct Answer: Marked action on His-Purkinje system and ventricular myocardium

Q18. Which drug interaction concern is most relevant when prescribing lorcainide?

  • Synergistic risk of hyperkalemia with ACE inhibitors
  • Increased plasma levels with drugs that inhibit hepatic metabolism
  • Complete antagonism by H2 blockers
  • No clinically significant drug interactions known

Correct Answer: Increased plasma levels with drugs that inhibit hepatic metabolism

Q19. In overdose or toxicity, lorcainide most likely produces which clinical picture?

  • Excessive bleeding and coagulopathy
  • Marked QRS widening with hypotension and ventricular arrhythmias
  • Painful peripheral neuropathy only
  • Profound hyperglycemia as predominant sign

Correct Answer: Marked QRS widening with hypotension and ventricular arrhythmias

Q20. Which patient characteristic increases the risk of adverse outcomes with lorcainide?

  • Young age without heart disease
  • Structural heart disease or recent myocardial infarction
  • History of seasonal allergic rhinitis only
  • Controlled hypothyroidism on stable therapy

Correct Answer: Structural heart disease or recent myocardial infarction

Q21. Which laboratory tests should be periodically monitored in a patient on lorcainide?

  • Liver function tests and renal function tests
  • Only serum amylase
  • Exclusive daily blood glucose
  • Urine culture every week

Correct Answer: Liver function tests and renal function tests

Q22. Compared with Class IB agents, Class IC drugs like lorcainide have which distinguishing property?

  • Weaker sodium-channel blockade at slow heart rates
  • More potent sodium-channel blockade with marked slowing of conduction
  • Stronger potassium-channel blockade than Class III agents
  • Primary action as calcium-channel blockers

Correct Answer: More potent sodium-channel blockade with marked slowing of conduction

Q23. Which clinical trial outcome is historically associated with Class IC sodium-channel blockers and influenced prescribing habits?

  • Demonstrated clear mortality benefit post-myocardial infarction
  • Increased mortality in certain post‑MI patients (CAST trial findings)
  • Elimination of atrial fibrillation recurrence in all patients
  • Universal renal protective effects

Correct Answer: Increased mortality in certain post‑MI patients (CAST trial findings)

Q24. Lorcainide’s minimal effect on which electrophysiological parameter differentiates it from Class III agents?

  • Minimal effect on QRS duration
  • Minimal effect on action potential duration and QT interval
  • Minimal effect on sodium-channel blockade
  • Minimal effect on conduction velocity

Correct Answer: Minimal effect on action potential duration and QT interval

Q25. Which symptom should prompt immediate evaluation for lorcainide toxicity?

  • New onset dizziness, syncope, or palpitations
  • Slight sore throat after seasonal exposure
  • Minor localized itching at a single skin site
  • Mild transient headache after caffeine intake

Correct Answer: New onset dizziness, syncope, or palpitations

Q26. In which scenario is lorcainide least appropriate?

  • Life‑threatening ventricular tachycardia in a structurally normal heart
  • Patients with recent myocardial infarction and reduced left ventricular function
  • Carefully monitored in-hospital initiation in selected patients
  • As part of a study of antiarrhythmic mechanisms in pharmacology teaching

Correct Answer: Patients with recent myocardial infarction and reduced left ventricular function

Q27. Why is ECG assessment of QRS duration important during dose titration of lorcainide?

  • Because QRS narrowing signals toxicity
  • Because progressive QRS widening correlates with increased sodium-channel blockade and toxicity risk
  • Because QRS duration is unrelated to drug effect
  • Because only PR interval matters for monitoring

Correct Answer: Because progressive QRS widening correlates with increased sodium-channel blockade and toxicity risk

Q28. Which pharmacodynamic effect explains reduced conduction velocity in ventricular tissue with lorcainide?

  • Blockade of fast sodium channels reducing upstroke amplitude and velocity
  • Activation of potassium efflux only
  • Enhancement of calcium influx in ventricles
  • Direct increase of pacemaker automaticity

Correct Answer: Blockade of fast sodium channels reducing upstroke amplitude and velocity

Q29. Which statement is correct regarding lorcainide and atrioventricular (AV) nodal conduction?

  • It selectively accelerates AV nodal conduction
  • It has relatively little direct effect on AV nodal slow channels compared with its effect on ventricular tissue
  • It exclusively blocks AV nodal tissue and not ventricular tissue
  • It causes immediate complete heart block in all patients

Correct Answer: It has relatively little direct effect on AV nodal slow channels compared with its effect on ventricular tissue

Q30. Which of the following best summarizes lorcainide’s pharmacological profile?

  • A potassium-channel blocker with major QT prolongation effects
  • A potent Class IC sodium-channel blocker that markedly slows conduction, can widen QRS, and carries proarrhythmic risk in structural heart disease
  • An antihypertensive with primary renal effects
  • A benign antiarrhythmic with no need for ECG monitoring

Correct Answer: A potent Class IC sodium-channel blocker that markedly slows conduction, can widen QRS, and carries proarrhythmic risk in structural heart disease

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