Disclosed is a liquid pharmaceutical formulation suitable for oral administration, comprising a suspension of an effective amount of micronized 2-(2-nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexanedione (nitisinone)； and a citric acid buffer having a pH in the range of 2.5 to 3.5. The formulation is useful in the treatment of disorders and diseases in which inhibition of 4-hydroxyphenylpyruvate dioxygenase (HPPD) is desirable, e.g. in hereditary tyrosinaemia type I and also in Parkinson&rsquo；s disease, depression, restless leg syndrome and alkaptonuria.
