Displaying 7 results of Isoniazid Impurities Isoniazid is a commonly used medication for the treatment of tuberculosis. However, during its manufacturing process, impurities may arise. These impurities can affect the quality, safety, and efficacy of the medication. Therefore, it is important to identify and quantify these impurities to ensure that the medication is safe for use. Common impurities include isonicotinyl hydrazine, isonicotinic acid, and 4-cyanopyridine.