The use of S(-)sodium 2-(4-isobutylphenyl)propionate (the sodium salt of S(+)-ibuprofen) in pharmaceutical compositions for the treatment of inflammation, pain and pyrexia is described. Preferred compositions comprise S(-)sodium 2-(4-isobutylphenyl)propionate dihydrate. Processes to prepare S(-)sodium 2-(4-isobutyl-phenyl)propionate and its use in a process to prepare S(+) 2-(4-isobutylphenyl)propionic acid of high enantiomeric purity are also described.