has role antitubercular agent carbohydrazide isoniazide 4-pyridinecarbohydrazide CHEBI:6030 isonicotinic acid hydrazide isoniazid isonicotinohydrazide isonicotinic hydrazide isonicotinoylhydrazide Isonicotinsaeurehydrazid Isoniazid chebi_ontology pyridine-4-carboxylic acid hydrazide A carbohydrazide obtained by formal condensation between pyridine-4-carboxylic acid and hydrazine. isonicotinic acid drug allergen