Dithiazanine iodide is an antinematodal agent, a substance administered in the treatment or control of nematode infestations including large roundworms, hookworms, whipworms, and strongyloides. Dithiazanine iodide tablets (Dizan) are administered orally immediately after feeding to dogs. The drug should be used with extreme caution in animals with kidney problems. Gastrointestinal disturbance is a common side effect. The drug's effectiveness may vary.