Helminthiasis and antifilarial therapy MCQs With Answer

Helminthiasis and antifilarial therapy MCQs With Answer

This quiz set is designed for M.Pharm students studying Pharmacotherapeutics II (MPP 202T) to deepen understanding of helminth infections and antifilarial pharmacology. Questions emphasize mechanisms of action, pharmacokinetics, therapeutic regimens, adverse effects, drug interactions, and resistance mechanisms of key anthelmintic and antifilarial agents. Clinical application such as mass drug administration strategies, special-population considerations (pregnancy, onchocerciasis co-endemicity), and novel approaches like targeting Wolbachia are included. These MCQs go beyond recall to test reasoning appropriate for postgraduate pharmacy curriculum and exam preparation, reinforcing safe and effective use of anthelmintics in clinical and public health settings.

Q1. Which of the following best describes the primary mechanism of action of albendazole against intestinal nematodes?

• Inhibition of acetylcholinesterase causing spastic paralysis
• Binding to beta-tubulin and inhibition of microtubule polymerization
• Blocking parasite glutamate-gated chloride channels leading to hyperpolarization
• Increasing parasite membrane permeability to calcium ions causing paralysis

Correct Answer: Binding to beta-tubulin and inhibition of microtubule polymerization

Q2. Which antifilarial strategy targets the endosymbiotic bacteria Wolbachia to achieve long-term sterilization of adult filarial worms?

• Single-dose diethylcarbamazine (DEC)
• High-dose ivermectin therapy every 3 months
• Prolonged doxycycline treatment
• Praziquantel combined with albendazole

Correct Answer: Prolonged doxycycline treatment

Q3. Which adverse reaction is most characteristically associated with rapid microfilaricidal activity of ivermectin or DEC in onchocerciasis?

• Hepatotoxicity with elevated transaminases
• Mazzotti reaction with intense pruritus, rash, and systemic symptoms
• Severe QT prolongation leading to torsades de pointes
• Renal tubular necrosis due to immune complex deposition

Correct Answer: Mazzotti reaction with intense pruritus, rash, and systemic symptoms

Q4. Which statement about albendazole pharmacokinetics is correct?

• Albendazole is well-absorbed on an empty stomach and should be taken fasting
• Albendazole absorption is enhanced by coadministration with a fatty meal
• Albendazole is primarily eliminated unchanged in the urine
• Albendazole bioavailability is unaffected by hepatic metabolism

Correct Answer: Albendazole absorption is enhanced by coadministration with a fatty meal

Q5. Which drug is the treatment of choice for schistosomiasis and acts by increasing parasite membrane permeability to calcium?

• Mebendazole
• Praziquantel
• Niclosamide

Correct Answer: Praziquantel

Q6. Which mechanism is the principal action of ivermectin on nematodes?

• Antagonism of nicotinic acetylcholine receptors at the neuromuscular junction
• Activation of glutamate-gated chloride channels causing hyperpolarization and paralysis
• Inhibition of mitochondrial oxidative phosphorylation in cestodes
• Interference with microtubule formation by binding to beta-tubulin

Correct Answer: Activation of glutamate-gated chloride channels causing hyperpolarization and paralysis

Q7. Which antifilarial agent is contraindicated in areas co-endemic for onchocerciasis because it causes severe ocular reactions?

• Ivermectin
• Diethylcarbamazine (DEC)
• Doxycycline
• Albendazole

Correct Answer: Diethylcarbamazine (DEC)

Q8. Which agent is minimally absorbed from the GI tract and acts locally to expel adult tapeworms by uncoupling oxidative phosphorylation?

• Praziquantel
• Niclosamide
• Pyrantel pamoate
• Mebendazole

Correct Answer: Niclosamide

Q9. What is a major molecular mechanism by which nematodes develop resistance to benzimidazole class drugs (e.g., albendazole, mebendazole)?

• Upregulation of P-glycoprotein efflux transporters in parasites
• Point mutations in the beta-tubulin gene that reduce drug binding
• Increased expression of glutamate-gated chloride channels
• Enhanced metabolic degradation by parasite cytochrome P450 enzymes

Correct Answer: Point mutations in the beta-tubulin gene that reduce drug binding

Q10. Which anthelmintic is a depolarizing neuromuscular blocker that causes spastic paralysis of intestinal nematodes by agonizing nicotinic receptors?

• Pyrantel pamoate
• Albendazole
• Praziquantel
• Niclosamide

Correct Answer: Pyrantel pamoate

Q11. For elimination of lymphatic filariasis in areas without onchocerciasis, WHO recommends mass drug administration that typically includes which combination?

• Ivermectin plus praziquantel annually
• Diethylcarbamazine (DEC) plus albendazole annually
• Single-dose doxycycline plus ivermectin annually
• Albendazole monotherapy monthly

Correct Answer: Diethylcarbamazine (DEC) plus albendazole annually

Q12. Which of the following adverse effects warrants caution and monitoring when using high-dose or prolonged albendazole therapy?

• Renal failure from crystal nephropathy
• Hepatotoxicity and reversible increases in liver enzymes
• Black box risk of torsades de pointes
• Severe neutropenia due to bone marrow suppression in all patients

Correct Answer: Hepatotoxicity and reversible increases in liver enzymes

Q13. Which antifilarial approach is most appropriate to achieve macrofilaricidal (adult worm killing) effect rather than only microfilaricidal effect?

• Single-dose ivermectin annually
• Short-course praziquantel targeted to adult worms
• Extended doxycycline therapy targeting Wolbachia endosymbionts
• Single-dose pyrantel administration

Correct Answer: Extended doxycycline therapy targeting Wolbachia endosymbionts

Q14. Which drug interaction is clinically significant for ivermectin and may increase CNS toxicity risk?

• Coadministration with strong CYP3A4 inhibitors that increase ivermectin plasma levels
• Combination with fatty meals that markedly reduce absorption
• Use with cholestyramine which increases ivermectin clearance
• Concurrent use of antibiotics that eliminate gut flora and reduce efficacy

Correct Answer: Coadministration with strong CYP3A4 inhibitors that increase ivermectin plasma levels

Q15. In neurocysticercosis management, which statement regarding antiparasitic therapy is most accurate?

• Praziquantel and albendazole are never used because they worsen seizures
• Albendazole (often with corticosteroids) is used to kill cysts and reduce inflammation
• Niclosamide is preferred because it crosses the blood–brain barrier effectively
• Pyrantel pamoate is the drug of choice for cerebral cysticercosis

Correct Answer: Albendazole (often with corticosteroids) is used to kill cysts and reduce inflammation

Q16. Which diagnostic or clinical consideration is crucial before administering mass ivermectin in a community?

• Screening for hepatic encephalopathy in all individuals
• Assessing for Loa loa co-endemicity to avoid severe encephalopathy from rapid microfilaricidal effects
• Ensuring all individuals are on a fat-free diet to reduce absorption
• Confirming absence of Wolbachia infection in filarial species

Correct Answer: Assessing for Loa loa co-endemicity to avoid severe encephalopathy from rapid microfilaricidal effects

Q17. Which statement correctly contrasts mebendazole and albendazole regarding systemic bioavailability and clinical implications?

• Mebendazole has higher systemic bioavailability than albendazole and is preferred for tissue helminth infections
• Albendazole is converted to an active sulfoxide metabolite with better systemic availability, making it useful for tissue-invasive helminths
• Both drugs have identical pharmacokinetics and interchangeable dosing for all indications
• Albendazole is not metabolized hepatically and is excreted unchanged

Correct Answer: Albendazole is converted to an active sulfoxide metabolite with better systemic availability, making it useful for tissue-invasive helminths

Q18. Which agent is specifically effective against intestinal cestodes like Diphyllobothrium latum and is given orally with minimal systemic absorption?

• Praziquantel
• Niclosamide
• Albendazole
• Ivermectin

Correct Answer: Niclosamide

Q19. Which of the following is an important contraindication for doxycycline use in antifilarial therapy?

• Pregnancy and children under 8 years due to effects on bone and teeth
• History of glaucoma due to increased intraocular pressure
• Concurrent use of albendazole because of antagonistic interactions
• Active schistosomiasis because doxycycline inactivates praziquantel

Correct Answer: Pregnancy and children under 8 years due to effects on bone and teeth

Q20. Which pharmacologic property of benzimidazoles explains their selective toxicity toward parasites compared with mammalian host cells?

• Higher affinity of benzimidazoles for helminth beta-tubulin than mammalian tubulin
• Ability to cross the blood–brain barrier selectively in parasites
• Exclusive inhibition of parasite-specific cytochrome P450 enzymes
• Activation by parasite-specific esterases to toxic metabolites

Correct Answer: Higher affinity of benzimidazoles for helminth beta-tubulin than mammalian tubulin

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