Which of the following agents is effective against both adult and larval forms of parasites?

Ivermectin is an agent known for its broad-spectrum efficacy against various parasitic infections, notably both adult and larval stages of certain parasites. It works by binding to specific receptors in the nervous system and muscle cells of the parasites, leading to paralysis and death. This mechanism of action is effective on mature parasites as well as their larval forms, making it particularly useful in treating conditions like lymphatic filariasis and onchocerciasis.

Other agents mentioned, such as albendazole, piperazine, and mebendazole, primarily target adult forms of parasites or have limited effects on larval stages. For instance, albendazole is more effective against adult worms and may not effectively clear all larval forms, while piperazine is generally limited to treating certain adult nematode infections and is less effective against larval stages. Mebendazole also primarily targets adult parasites. Therefore, the unique dual effectiveness of ivermectin against both life stages sets it apart as the preferred choice in this context.