Re: how do they work

Albendazole - Slow reduction in the ATP/general attack on the parasite metabolism which leads to energy depletion which leads slowly to death.

Fenbendazole - Similar action to mebendazole (glucose/metabolic reduction).

Nitazoxanide - General attack on the worm metabolism targeting specific enzymes.

Ivermectin - General attack directed at the small larvae (paralyze and death) and attack on the reproductive cycle of parasites. It won't do much against the adult worms apart from some reduction in breeding. It is somewhat poor paralyze agent compared to levamisole, pyrantel pamoate etc.