1-lt <1 ->IA

is an antagonist of thiamine (vitamin B₁). Rapidly dividing coccidia have a high requirement for thiamine. Amprolium has a safety margin of ~8:1 when used at the highest recommended level in feed (125-250 ppm). Because amprolium has poor activity against some Eimeria spp, its spectrum has been extended by using it in mixtures with the folic acid antagonists, ethopabate and sulfaquinoxaline. The primary use of amprolium today is for water treatment during clinical outbreaks.