Anthelmintic Drugs: Mebendazole and Albendazole and MCQ for GPAT, Pharmacist, NEETPG, Nursing exams
🔹 Class: Benzimidazole Anthelmintics
Used for: Roundworms, Hookworms, Whipworms, Pinworms, Hydatid disease (Albendazole)
🧬 Mechanism of Action (Pharmacodynamics)
| Drug | Mechanism of Action |
|---|---|
| Mebendazole | 1. Binds β-tubulin, inhibits microtubule polymerization → impairs glucose uptake 2. ↓ ATP → worm paralysis & death |
| Albendazole | Same as Mebendazole + active metabolite (albendazole sulfoxide) is systemically active & acts on tissue stages |
💊 Pharmacokinetics
| Parameter | Mebendazole | Albendazole |
|---|---|---|
| Absorption | Poor oral absorption | Poor oral absorption (↑ with fatty meal) |
| Metabolism | Liver (extensive first-pass) | Liver (converted to albendazole sulfoxide) |
| Half-life | 2–6 hours | 8–12 hours (active metabolite) |
| Distribution | Mostly in GI tract | Systemic (effective in tissue infections) |
| Excretion | Feces | Urine and bile |
⚠️ Adverse Effects
| Common | Rare/Serious |
|---|---|
| GI discomfort, nausea | Bone marrow suppression (Albendazole) |
| Headache, dizziness | Hepatotoxicity (monitor LFTs) |
| Alopecia (long-term use) | Teratogenicity (avoid in pregnancy) |
🔄 Drug-Drug Interactions
| Interaction | Effect |
|---|---|
| Cimetidine | ↑ plasma levels of mebendazole |
| Dexamethasone / Praziquantel | ↑ Albendazole sulfoxide levels |
| Carbamazepine / Phenytoin | ↓ Albendazole effectiveness |
⚕️ Clinical Uses
| Mebendazole | Albendazole |
|---|---|
| Enterobiasis (pinworm), ascariasis | Same as mebendazole + Cysticercosis, Hydatid disease |
| Hookworm, whipworm | Neurocysticercosis (CNS penetration) |
✅ MCQs on Mebendazole & Albendazole
1. What is the primary mechanism of action of Mebendazole?
A. GABA receptor agonist
B. Acetylcholinesterase inhibitor
C. Inhibition of glucose uptake and microtubule polymerization
D. Activation of chloride ion channels
🟩 Answer: C
2. Albendazole is preferred over Mebendazole in:
A. Pinworm infection
B. Hydatid disease
C. Hookworm infection
D. Roundworm infection
🟩 Answer: B
3. Which of the following increases albendazole sulfoxide concentration?
A. Cimetidine
B. Phenytoin
C. Dexamethasone
D. Both A & C
🟩 Answer: D
4. A known adverse effect of long-term albendazole therapy is:
A. Seizures
B. Alopecia
C. Blindness
D. Tinnitus
🟩 Answer: B
5. Albendazole absorption is enhanced by:
A. Empty stomach
B. Fatty meal
C. Antacids
D. Dairy products
🟩 Answer: B