To obtain the subject treating agent having a high selectivity against phosphodiesterase type V as a decomposing enzyme for cyclic GMP, and a potent inhibiting action thereto by containing a specific condensed pyridazine- based compound as an active ingredient.
This treating agent for impotentia erigendi is a condensed pyridazine-based compound of formula I {ring C is an unsaturated 5- or 6-membered ring allowed to have a hetero atom; (n) is 0, 1 to 4; R1 is a halogen, a (substituted)alkyl, a (substituted) lower alkyl, etc.; X is NR6 [R6 is H, a (substituted)alkyl, etc.] or N; Y is CO, C(B) (B is H, a halogen, etc.; formula II is a double bond or a single bond} or a pharmacologically permissible salt thereof, concretely e.g. 1-chloro-4-(3-chloro-4-methoxybenzyl)amino-6- cyanophthalazine. Further, the agent is preferably administered by 5μg-100mg for an adult as one time dose through intravenous administration, etc.
KABASAWA YASUHIRO
ABE SHINYA
SHIBAZAKI MASAYOSHI
ISHIHARA HIROKI
KODAMA KOTARO
ADACHI HIDEYUKI
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