The compounds of formula (1) in which R1, R7, R8, R9, R10, R17, R18, R19, R20 and m have the meanings as given in the description, are novel effective inhibitors of type 4 and type 5 phosphodiesterase.式(1)[式中、R1、R7、R8、R9、R10、R17、R18、R19、R20及びmは、明細書中に示される意味を有する]の化合物は、4型及び5型のホスホジエステラーゼの新規の有効な阻害薬である。