Chloride channel opener

A compound represented by formula (IV):

• wherein L, M and N are hydrogen, hydroxy, halogen, lower alkyl, hydroxy(lower)alkyl, or oxo, wherein at least one of L and M is a group other than hydrogen, and the five-membered ring may have one or more double bonds;
• R′ and R″ are hydrogen, lower alkyl, aryl, alkyl- or aryl-sulfonyl, lower alkenyl or lower alkynyl;
• B is —CH2—CH2—, —CH═CH— or —C≡C—;
• R1 is a saturated or unsaturated bivalent lower or medium aliphatic hydrocarbon residue, which is unsubstituted or substituted with halogen, alkyl, hydroxy, oxo, or aryloxy, and at least one carbon atom in the aliphatic hydrocarbon is optionally substituted by oxygen, nitrogen or sulfur;
• and
• Ra is a saturated or unsaturated lower or medium aliphatic hydrocarbon residue, which is unsubstituted or substituted with halogen, oxo, hydroxy, lower alkoxy, lower alkanoyloxy, cyclo(lower)alkyl, cyclo(lower)alkyloxy, aryl, or aryloxy;
• cyclo(lower)alkyl;
• cyclo(lower)alkyloxy;
• aryl;
• or aryloxy.