This concise MCQ collection on Thiabendazole, Mebendazole, and Albendazole is designed for B. Pharm students to deepen understanding of benzimidazole anthelmintics. Questions focus on mechanism of action, pharmacokinetics, clinical indications, dosing principles, adverse effects, drug interactions, contraindications, resistance mechanisms, and monitoring. Emphasis on drug chemistry, absorption, metabolism to active metabolites, safety profiles, and therapeutic use prepares students for exams and clinical pharmacy practice. Each question promotes critical thinking about pharmacology and therapeutics relevant to helminthic infections and patient safety. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. Which is the primary mechanism of action shared by Thiabendazole, Mebendazole, and Albendazole?
- Inhibition of dihydrofolate reductase
- Blockade of acetylcholine receptors at neuromuscular junction
- Binding to beta-tubulin and inhibition of microtubule polymerization
- Inhibition of DNA gyrase
Correct Answer: Binding to beta-tubulin and inhibition of microtubule polymerization
Q2. Which benzimidazole is extensively metabolized in the liver to an active sulfoxide metabolite that attains systemic levels?
- Mebendazole
- Thiabendazole
- Albendazole
- Pyrantel
Correct Answer: Albendazole
Q3. Which statement about mebendazole pharmacokinetics is most accurate?
- Mebendazole is highly bioavailable and achieves high CSF concentrations
- Mebendazole has poor oral absorption and largely acts in the intestinal lumen
- Mebendazole is primarily eliminated unchanged in urine
- Mebendazole is activated by plasma esterases to an active metabolite
Correct Answer: Mebendazole has poor oral absorption and largely acts in the intestinal lumen
Q4. For which clinical condition is albendazole the preferred benzimidazole agent?
- Enterobiasis (pinworm) limited to the gut
- Cutaneous larva migrans treated topically
- Neurocysticercosis and systemic hydatid disease
- Superficial dermatophyte infection
Correct Answer: Neurocysticercosis and systemic hydatid disease
Q5. Thiabendazole is classically used for which indication?
- Systemic echinococcosis maintenance therapy
- Topical and oral therapy for strongyloidiasis and cutaneous larva migrans
- Routine prophylaxis against schistosomiasis
- Tuberculosis adjunct therapy
Correct Answer: Topical and oral therapy for strongyloidiasis and cutaneous larva migrans
Q6. Which adverse effect requires regular monitoring during prolonged albendazole therapy?
- Renal tubular acidosis
- Hepatotoxicity (elevated liver enzymes)
- Severe hypertension
- Pulmonary fibrosis
Correct Answer: Hepatotoxicity (elevated liver enzymes)
Q7. Which benzimidazole is contraindicated in pregnancy due to teratogenic risk?
- Mebendazole
- Pyrantel pamoate
- Praziquantel
- Avermectin
Correct Answer: Mebendazole
Q8. During prolonged high-dose therapy for hydatid disease which laboratory parameter should be monitored because of bone marrow suppression risk?
- Serum creatinine only
- Complete blood count (CBC)
- Serum amylase
- Fasting blood glucose
Correct Answer: Complete blood count (CBC)
Q9. Co-administration of which drug class is most likely to decrease plasma concentrations of albendazole sulfoxide?
- CYP3A4 inducers such as carbamazepine or phenytoin
- CYP3A4 inhibitors such as ketoconazole
- Proton pump inhibitors such as omeprazole
- H2 blockers such as ranitidine
Correct Answer: CYP3A4 inducers such as carbamazepine or phenytoin
Q10. Which drug is the treatment of choice for uncomplicated Enterobius vermicularis (pinworm) infection in many protocols?
- Albendazole
- Mebendazole
- Thiabendazole topical ointment
- Ivermectin oral single dose
Correct Answer: Mebendazole
Q11. What is the commonly recommended single-dose mebendazole regimen for pinworm in adults/children?
- 100 mg single dose (chewable), repeat after 2 weeks if needed
- 400 mg daily for 7 days
- Albendazole 400 mg single dose is required instead
- Topical application is always preferred
Correct Answer: 100 mg single dose (chewable), repeat after 2 weeks if needed
Q12. Which statement about albendazole distribution is correct?
- Albendazole unchanged reaches high CSF concentrations
- The hepatic metabolite albendazole sulfoxide penetrates the CSF and cysts
- Albendazole is confined to the gut lumen and is not systemic
- Albendazole accumulates primarily in bone tissue
Correct Answer: The hepatic metabolite albendazole sulfoxide penetrates the CSF and cysts
Q13. Which molecular change in parasites commonly confers resistance to benzimidazoles?
- Mutation in acetylcholinesterase gene
- Mutation in beta-tubulin gene reducing drug binding
- Increased efflux via P-glycoprotein in host gut
- Overexpression of cytochrome P450 in parasite
Correct Answer: Mutation in beta-tubulin gene reducing drug binding
Q14. Which benzimidazole formulation or practice enhances absorption of albendazole?
- Taking albendazole on an empty stomach
- Taking albendazole with a fatty meal
- Crushing the tablet and administering rectally
- Co-administration with antacids to reduce gastric acidity
Correct Answer: Taking albendazole with a fatty meal
Q15. For cutaneous larva migrans, which agent is often used topically or orally?
- Mebendazole oral single dose
- Thiabendazole topical or oral
- Albendazole is ineffective against cutaneous larva migrans
- Metronidazole topical cream
Correct Answer: Thiabendazole topical or oral
Q16. Which benzimidazole formulation is commonly available as a chewable tablet convenient for pediatric dosing?
- Albendazole only as parenteral injection
- Mebendazole chewable tablet
- Thiabendazole oral solution only
- Praziquantel chewable is standard
Correct Answer: Mebendazole chewable tablet
Q17. Which is the safest statement regarding benzimidazole use in pregnancy?
- Albendazole and mebendazole are safe in the first trimester
- All benzimidazoles are strictly contraindicated in pregnancy unless benefits outweigh risks
- Mebendazole is recommended routinely during pregnancy
- Thiabendazole is the recommended anthelmintic in pregnancy
Correct Answer: All benzimidazoles are strictly contraindicated in pregnancy unless benefits outweigh risks
Q18. Which monitoring set is appropriate before and during prolonged albendazole therapy?
- Urine culture monthly only
- Baseline and periodic liver function tests (LFTs) and complete blood count (CBC)
- No monitoring required for courses longer than a month
- Serial ECGs weekly
Correct Answer: Baseline and periodic liver function tests (LFTs) and complete blood count (CBC)
Q19. The primary therapeutic effect of benzimidazoles on helminths is due to:
- Direct DNA fragmentation in parasites
- Inhibition of parasite microtubule function leading to impaired glucose uptake
- Competitive antagonism of nicotinic receptors
- Chelation of essential divalent cations in host blood
Correct Answer: Inhibition of parasite microtubule function leading to impaired glucose uptake
Q20. Which benzimidazole is most suitable for systemic helminth infections because of better systemic absorption of its metabolite?
- Mebendazole
- Pyrantel pamoate
- Albendazole
- Niclosamide
Correct Answer: Albendazole
Q21. Which adverse effect is particularly associated with thiabendazole therapy?
- Severe cholestatic jaundice in all patients
- Local irritation and GI upset; possible neuropsychiatric symptoms
- Irreversible renal failure
- Marked hyperglycemia
Correct Answer: Local irritation and GI upset; possible neuropsychiatric symptoms
Q22. Which statement about mebendazole dosing and household treatment is correct for Enterobius outbreaks?
- Treat only the symptomatic individual once
- Treat all close contacts or household members simultaneously to prevent reinfection
- Disinfection of household linen alone is sufficient; no drug therapy needed
- Use topical thiabendazole for household prophylaxis
Correct Answer: Treat all close contacts or household members simultaneously to prevent reinfection
Q23. Why is albendazole often preferred over mebendazole for neurocysticercosis?
- Albendazole has better luminal activity but poor systemic penetration
- Albendazole’s active metabolite attains therapeutic CSF and cyst concentrations
- Mebendazole is more teratogenic and therefore avoided
- Mebendazole causes severe renal toxicity in neurocysticercosis
Correct Answer: Albendazole’s active metabolite attains therapeutic CSF and cyst concentrations
Q24. Which precaution is important when combining albendazole therapy with corticosteroids in neurocysticercosis?
- Corticosteroids reduce albendazole absorption and should be avoided
- Corticosteroids are used to control inflammatory response from dying parasites
- Corticosteroids markedly increase albendazole hepatotoxicity and are contraindicated
- Corticosteroids convert albendazole to inactive metabolites
Correct Answer: Corticosteroids are used to control inflammatory response from dying parasites
Q25. Which clinical monitoring is least relevant for a patient on short-course single-dose mebendazole for pinworm?
- Immediate CBC monitoring for agranulocytosis
- Education about hygiene to prevent reinfection
- Repeat dosing after two weeks if reinfection suspected
- Treat close contacts
Correct Answer: Immediate CBC monitoring for agranulocytosis
Q26. Which statement best describes resistance concerns with benzimidazoles in parasitology?
- Resistance is impossible because of host immunity
- Resistance may arise via point mutations in parasite beta-tubulin genes
- Resistance occurs only via increased drug excretion by the host
- Resistance is mediated by parasite viral co-infection
Correct Answer: Resistance may arise via point mutations in parasite beta-tubulin genes
Q27. Which drug interaction is clinically important with albendazole when treating cysticercosis in epileptic patients?
- Antiepileptic enzyme inducers may lower albendazole levels requiring dose adjustments
- Antiepileptics universally increase albendazole concentration and cause toxicity
- Albendazole potentiates opioid analgesics leading to respiratory depression
- No interactions are known between albendazole and antiepileptics
Correct Answer: Antiepileptic enzyme inducers may lower albendazole levels requiring dose adjustments
Q28. Which benzimidazole is most suitable for treating visceral larva migrans (Toxocara) with systemic involvement?
- Mebendazole for systemic disease only
- Albendazole due to better systemic exposure
- Topical thiabendazole for systemic disease
- Niclosamide for systemic larva migrans
Correct Answer: Albendazole due to better systemic exposure
Q29. Which patient counseling point is important when dispensing albendazole for hydatid disease?
- No need for liver tests before or during therapy
- Take with a fatty meal and monitor LFTs during prolonged therapy
- Complete course regardless of pregnancy status without consultation
- Albendazole is ineffective if given with food
Correct Answer: Take with a fatty meal and monitor LFTs during prolonged therapy
Q30. Which statement distinguishes mebendazole from albendazole in terms of primary clinical use?
- Mebendazole is mainly used for systemic hydatid disease
- Mebendazole is primarily used for intestinal nematodes with minimal systemic absorption
- Mebendazole is the drug of choice for neurocysticercosis
- Mebendazole has superior CSF penetration compared to albendazole
Correct Answer: Mebendazole is primarily used for intestinal nematodes with minimal systemic absorption
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