Toltrazuril is an antiprotozoal drug used in veterinary medicine to treat coccidiosis, a parasitic disease. Toltrazuril impurities are substances that are not the active ingredient of the drug but may be present in small amounts during the manufacturing process or storage. These impurities can affect the purity, safety, and efficacy of the drug, and their identification and control are critical for ensuring quality and safety in the final product.