Patent ID: RE38970

Claim:
A heterocyclic compound of the formula (I) wherein one of R 1 , R 2 and R 3 is hydroxy, carboxy, alkoxycarbonyl, a group of the formula —NR 9 R 10 wherein R 9 and R 10 are each independently hydrogen atom or lower alkyl, or alkyl or alkenyl substituted by hydroxy, carboxy, sulfonic add group or phosphoric acid group, alkoxy-carbonyl or a group of the formula —NR 9 R 10 wherein R 9 and R 10 are each independently hydrogen atom or lower alkyl, and the other two are each independently hydrogen atom, lower alkyl or lower alkoxy; either R 3 or R 4 is a group of the formula —NHCOR 7 wherein R 7 is alkyl, alkoxyalkyl, alkylthioalkyl, cycloalkyl, cycloalkylalkyl, aryl, arylalkyl or a group of the formula —NHR 8 wherein R 8 is alkyl, cycloalkyl, cycloalkylalkyl, aryl or arylalkyl, and the other is hydrogen atom, lower alkyl or lower alkoxy; R 6 is alkyl, alkenyl, alkoxyalkyl, alkylthioalkyl, cycloalkyl, cycloalkylalkyl or arylalkyl; and Z is or a pharmaceutically acceptable salt thereof, provided that when one of R 1 , R 2 and R 3 its carboxy or alkoxycarbonyl, Z should be a group of the formula