Question

Consider the following: 1. Giardiasis 2. Microfilaria 3. Macrofilaria 4. Cestodes. In the treatment of which of these is albendazole the preferred drug?

• A. 1, 2, 3 and 4
• B. 2 and 4
• C. 1 and 4
• D. 1 only

Hint:

Recall which of these four is treated with metronidazole instead, and which needs diethylcarbamazine for the adult worm.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
This is a pharmacology question testing the spectrum of albendazole, a broad-spectrum benzimidazole anthelmintic, across four different parasitic conditions: giardiasis, microfilaria (the larval blood form of filarial worms), macrofilaria (the adult filarial worm), and cestode (tapeworm) infections.

Step 2: Key Concept or Approach:
The right approach is to recall which drug class is the actual drug of choice for each parasite rather than assuming albendazole covers everything just because it has a wide spectrum. Albendazole works by binding to parasite beta-tubulin and blocking microtubule formation, which is lethal to helminth larvae and adult worms in tissues, and it also has activity against circulating microfilariae when combined in filariasis control programmes.

Step 3: Working Through the Options:
For giardiasis, the preferred drugs are metronidazole or tinidazole, which act on the trophozoite's anaerobic metabolism; albendazole is only a second-line alternative, so it does not qualify as a "preferred drug" indication here. For microfilaria, albendazole (often combined with diethylcarbamazine or ivermectin in mass drug administration) is used and included in the standard filariasis treatment regimen. For macrofilaria (the adult worm), diethylcarbamazine remains the primary agent and albendazole is not the preferred choice for killing adult worms. For cestode infections such as hydatid disease and neurocysticercosis, albendazole is clearly the preferred drug because of its excellent tissue penetration into cysts.

Step 4: Conclusion:
Albendazole is the preferred drug for microfilaria and cestode infections, so the correct answer is "2 and 4".