Thermodynamically stable form of (R) -3-(4-fluorophenyl) sulfonyl amino -1,2,3,4-tetrahydro-9H-carbazole-9-propanoic acid (ramatroban)

摘要

The present invention relates to a thermodynamically stable modification of the active compound ramatroban of formula (I). The thermodynamically stable form is prepared either by melting of the metastable form and subsequent recrystallization or by seeding a solution of the metastable active compound with a seed crystal of the thermodynamically stable form. The thermodynamically stable active compound can be employed as an asthma agent.