Abstract: The present invention relates to the use of (5S)-{[2-(4-carboxyphenyl)ethyl][2-(2-{[3-chloro-4?-(trifluoromethyl)biphenyl-4-yl]methoxy}phenyl)ethyl]-amino}-5,6,7,8-tetrahydroquinoline-2-carboxylic acid of formula (I), prefer-ably in form of one of its salts or solvates or hydrates, preferably (5S)-{[2-(4-carboxyphenyl)ethyl][2-(2-{[3-chloro-4?-(trifluoromethyl)biphenyl-4-yl]methoxy}phenyl)ethyl]-amino}-5,6,7,8-tetrahydroquinoline-2-carboxylic acid in form of monohydrate (I) of formula (I-M-I) or (5S)-{[2-(4-carboxyphenyl)ethyl][2-(2-{[3-chloro-4?-(trifluoromethyl)biphenyl-4-yl]methoxy}phenyl)-ethyl]-amino}-5,6,7,8-tetrahydroquinoline-2-carboxylic acid inform of mono hydrate (II) of formula (I-M-II), in the inhalative treatment of cardiopulmonary and pulmonary disorders, such as pulmonary arterial hypertension (P AH), chronic thromboembolic pulmonary hypertension (CTEPH) and pulmonary hypertension (PH) associated with chronic lung disease (PH group 3) such as pulmonary hypertension in chronic obstructive pulmo