Mexiletine hydrochloride MCQs With Answer

Mexiletine hydrochloride MCQs With Answer

Mexiletine hydrochloride is an oral Class IB antiarrhythmic and a structural analogue of lidocaine, widely studied in B.Pharm pharmacology. This concise, keyword-rich introduction covers mechanism of action (fast sodium channel blockade), pharmacokinetics (oral absorption, hepatic metabolism), clinical uses (ventricular arrhythmias, off-label neuropathic pain), adverse effects (gastrointestinal and CNS), important drug interactions (CYP inhibitors/inducers), dosing principles, contraindications and monitoring. These core topics reinforce understanding of mechanism, safety, formulation and therapeutic monitoring essential for pharmacy practice. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which antiarrhythmic class does mexiletine hydrochloride belong to?

• Class IA
• Class IB
• Class IC
• Class III

Correct Answer: Class IB

Q2. Mexiletine’s primary mechanism of action is:

• Beta-adrenergic receptor blockade
• Potassium channel prolongation
• Fast sodium channel blockade
• Calcium channel inhibition

Correct Answer: Fast sodium channel blockade

Q3. Mexiletine is structurally most closely related to which local anesthetic?

• Bupivacaine
• Procaine
• Lidocaine
• Tetracaine

Correct Answer: Lidocaine

Q4. The preferred clinical indication for mexiletine is:

• Atrial fibrillation rate control
• Supraventricular tachycardia acute conversion
• Chronic management of ventricular arrhythmias
• Hypertension

Correct Answer: Chronic management of ventricular arrhythmias

Q5. Which route of administration is mexiletine hydrochloride primarily available in?

• Intravenous infusion
• Oral capsules/tablets
• Topical ointment
• Inhalation aerosol

Correct Answer: Oral capsules/tablets

Q6. Mexiletine shows greatest sodium-channel blocking effect on:

• Rested, non-depolarized cardiac tissue
• Rapidly repolarizing atrial tissue only
• Depolarized or ischemic ventricular tissue
• Vascular smooth muscle

Correct Answer: Depolarized or ischemic ventricular tissue

Q7. The primary organ responsible for mexiletine metabolism is the:

• Liver
• Kidney
• Lungs
• Skin

Correct Answer: Liver

Q8. Which cytochrome P450 interaction is most relevant for mexiletine?

• CYP3A4 inducers increase mexiletine levels
• CYP inhibitors may increase mexiletine plasma concentration
• Mexiletine is not metabolized by CYP enzymes
• CYP enzymes only affect renal excretion of mexiletine

Correct Answer: CYP inhibitors may increase mexiletine plasma concentration

Q9. A common adverse effect of mexiletine is:

• Severe hyperglycemia
• Gastrointestinal upset (nausea, vomiting)
• Ototoxicity
• Profound bradycardia in all patients

Correct Answer: Gastrointestinal upset (nausea, vomiting)

Q10. Which central nervous system adverse effects are associated with mexiletine?

• Visual hallucinations exclusively
• Dizziness, tremor and ataxia
• Progressive memory loss in all patients
• Immediate coma after first dose

Correct Answer: Dizziness, tremor and ataxia

Q11. Mexiletine shortens which phase of the cardiac action potential in ventricular muscle?

• Phase 0 only, without affecting duration
• Action potential duration (shortening)
• Prolongs action potential duration markedly
• No effect on action potential

Correct Answer: Action potential duration (shortening)

Q12. Typical dosing frequency commonly used for maintenance therapy with mexiletine is:

• Once daily
• Every 8 hours (three times daily)
• Every 30 minutes
• Once weekly

Correct Answer: Every 8 hours (three times daily)

Q13. Mexiletine is considered useful as an oral alternative to which intravenous drug for ventricular arrhythmias?

• Propranolol
• Amiodarone
• Lidocaine
• Verapamil

Correct Answer: Lidocaine

Q14. In which condition is mexiletine generally contraindicated or used with caution?

• Cardiogenic shock
• Stable angina
• Controlled hypertension
• Hyperthyroidism without heart block

Correct Answer: Cardiogenic shock

Q15. Which monitoring is most appropriate when starting mexiletine for arrhythmias?

• Regular audiometry
• Periodic ECG monitoring for proarrhythmia
• No monitoring is needed at any time
• Only blood glucose monitoring

Correct Answer: Periodic ECG monitoring for proarrhythmia

Q16. Mexiletine’s bioavailability after oral dosing is best described as:

• Negligible due to complete first-pass metabolism
• High oral bioavailability compared with lidocaine
• Only effective when given IV
• Completely inactivated in the gut

Correct Answer: High oral bioavailability compared with lidocaine

Q17. One off-label therapeutic use of mexiletine is:

• Acute ischemic stroke
• Chronic neuropathic pain management
• Management of bacterial infections
• Treatment of hypothyroidism

Correct Answer: Chronic neuropathic pain management

Q18. Which drug class could significantly increase mexiletine levels via CYP inhibition?

• Strong CYP inhibitors such as certain macrolide antibiotics
• Bulk-forming laxatives
• Non-absorbable antacids only
• Topical corticosteroids

Correct Answer: Strong CYP inhibitors such as certain macrolide antibiotics

Q19. Renal impairment primarily affects mexiletine by:

• Increasing parent drug hepatic clearance
• Accumulation of metabolites requiring dose consideration
• Eliminating all adverse effects
• Preventing oral absorption entirely

Correct Answer: Accumulation of metabolites requiring dose consideration

Q20. Which statement about mexiletine and pregnancy/breastfeeding is most appropriate for B.Pharm students?

• It is universally safe in pregnancy and breastfeeding without restrictions
• Use only if potential benefit justifies risk; consult reference guidance
• It is banned in all pregnant patients
• No data exist, so it should be given freely

Correct Answer: Use only if potential benefit justifies risk; consult reference guidance

Q21. In case of severe mexiletine-induced sodium-channel blockade toxicity with hypotension and wide QRS, an important acute treatment is:

• High-dose insulin only
• Sodium bicarbonate administration
• Immediate hemodialysis as first-line
• Oral activated charcoal only

Correct Answer: Sodium bicarbonate administration

Q22. Which laboratory test is most directly useful for routine monitoring of mexiletine therapy?

• Therapeutic drug monitoring is routinely required for all patients
• Periodic ECGs and clinical assessment rather than routine serum level checks
• Daily complete blood counts for every patient
• Random urine drug screening

Correct Answer: Periodic ECGs and clinical assessment rather than routine serum level checks

Q23. A pharmacodynamic property of Class IB agents like mexiletine is that they:

• Preferentially affect long action potential tissues
• Act more on ischemic, depolarized tissue and shorten repolarization
• Cause marked QT prolongation as a class effect
• Are the most effective drugs for atrial flutter chronic therapy

Correct Answer: Act more on ischemic, depolarized tissue and shorten repolarization

Q24. Which adverse hematologic reaction has been reported rarely with mexiletine?

• Aplastic anemia commonly in all users
• Blood dyscrasias such as neutropenia or agranulocytosis (rare)
• Polycythemia in most patients
• No hematologic effects ever reported

Correct Answer: Blood dyscrasias such as neutropenia or agranulocytosis (rare)

Q25. When counseling a patient starting mexiletine, which instruction is appropriate?

• Take doses at regular intervals, often every 8 hours, to maintain effect
• Skip doses when feeling better and double next dose
• Only take with dairy products to enhance absorption
• Avoid all fluids for two hours after dosing

Correct Answer: Take doses at regular intervals, often every 8 hours, to maintain effect

Q26. Which statement about mexiletine’s onset and duration is true?

• It has extremely rapid onset and must be given IV only
• Oral onset is slower than IV lidocaine, but has a longer duration suitable for chronic use
• It has no onset of action when used chronically
• Duration is shorter than a single hour for oral dosing

Correct Answer: Oral onset is slower than IV lidocaine, but has a longer duration suitable for chronic use

Q27. Which patient population requires extra caution or dose adjustment with mexiletine?

• Patients with severe hepatic impairment
• Young healthy adults with no comorbidities
• Patients with seasonal allergies only
• Those who have previously tolerated lidocaine IV without issues

Correct Answer: Patients with severe hepatic impairment

Q28. The reason mexiletine can be used orally whereas lidocaine cannot is because mexiletine:

• Is inactivated by gastric acid
• Has significant oral bioavailability and is less susceptible to first-pass elimination
• Is identical to lidocaine in pharmacokinetics
• Is only effective after parenteral administration

Correct Answer: Has significant oral bioavailability and is less susceptible to first-pass elimination

Q29. Which of the following interactions could reduce mexiletine plasma concentration?

• Coadministration with strong CYP inducers like rifampin
• Coadministration with grapefruit juice
• Concurrent use of strong CYP inhibitors
• Taking mexiletine with a glass of milk

Correct Answer: Coadministration with strong CYP inducers like rifampin

Q30. For a B.Pharm student preparing to counsel a patient, which point best summarizes mexiletine’s risk-benefit profile?

• High efficacy for all arrhythmias with no adverse effects
• Useful oral Class IB agent for ventricular arrhythmias and some neuropathic pain, but requires monitoring for CNS, GI and cardiac adverse effects and interaction risks
• Only a topical medication with negligible systemic risk
• Should be used as first-line therapy for hypertension

Correct Answer: Useful oral Class IB agent for ventricular arrhythmias and some neuropathic pain, but requires monitoring for CNS, GI and cardiac adverse effects and interaction risks

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