The invention concerns a liquid pharmaceutical formulation suitable for oral admimstration, comprising a suspension of an effective amount of micromzed 2-(2- nitro-4-trifluoromethylbenzoyl)-l,3-cyclohexanedione (nitisinone) and 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 .
