There is provided a pharmaceutical dosage form that is suitable for peroral administration to the gastrointestinal tract, which dosage form comprises a pharmaceutical composition in the form of a particulate mixture comprising solid particles of N-butyloxycarbonyl-3-(4-imidazol-1-ylmethylphenyl)-5-iso-butylthiophene-2-sulfonamide (C21), or a pharmaceutically-acceptable salt thereof, admixed with a blend of carrier particles with weight- and/or a volume-based mean diameter, and/or a structural/particle density, that is/are similar to the weight- and/or volume-based mean diameter, and/or the structural/particle density, of the solid particles of C21, and a glidant, which composition is contained within a capsule that is suitable for such peroral administration. Preferred carrier particles have a weight- and/or a volume-based mean diameter that is less than about 100 μm. Preferred carrier particle materials include mannitol. Preferred glidants comprise colloidal silica. Such dosage forms find utility in the treatment of lung diseases, such as idiopathic pulmonary fibrosis, sarcoidosis and respiratory virus-induced tissue damage.