Compounds of formula (I) wherein: R1 is heteroaryl optionally substituted by methyl, ethyl, halo or ═O; and R2 is H, methyl or ethyl. and salts thereof are KMO inhibitors and may be useful in the treatment of various disorders, for example acute pancreatitis, chronic kidney disease, other conditions associated with systemic inflammatory response syndrome (SIRS), Huntington's disease, Alzheimer's disease, spinocerebellar ataxias, Parkinson's disease, AIDS-dementia complex, HIV infection, amylotrophic lateral sclerosis (ALS), depression, schizophrenia, sepsis, cardiovascular shock, severe trauma, acute lung injury, acute respiratory distress syndrome, acute cholecystitis, severe burns, pneumonia, extensive surgical procedures, ischemic bowel disease, severe acute hepatic disease, severe acute hepatic encephalopathy or acute renal failure.