Alternative drugs for Giardia lamblia infections besides metronidazole include which?

• A. Tinidazole or nitazoxanide
• B. Albendazole
• C. Praziquantel
• D. Ivermectin

Answer: (B)

Giardia infections can be treated with drugs that are effective against protozoa in a similar way to metronidazole. The best-known alternatives are tinidazole, which is another nitroimidazole like metronidazole and works by forming reactive nitro radicals that damage Giardia’s DNA, and nitazoxanide, which has activity against Giardia through a different mechanism that disrupts anaerobic energy metabolism. These options are commonly used when metronidazole cannot be used or if a patient needs an alternative due to side effects or intolerance.

Albendazole, while useful against many helminths, does not have reliable efficacy against Giardia and is not typically used as an alternative for Giardia infections. Praziquantel targets trematodes and cestodes, not Giardia, and ivermectin is aimed at many nematodes, not Giardia. Therefore, the most appropriate alternatives among the listed choices are tinidazole and nitazoxanide.