Pancreatitis is classified mainly into acute pancreatitis caused by autodigestion due to intracellular activation of the digestive enzymes produced in the exocrine pancreas and chronic pancreatitis which, by fibrosis, progresses to irreversible functional failure of the pancreas. The etiology of pancreatitis remains to be fully elucidated as yet. The therapeutic approach to acute pancreatitis consists of, to start with, conservative therapies such as removal of causes, pancreatic protection, arrest of pancreatic autodigestion, and removal of pain. Referring to pharmacotherapy, arrest of pancreatic autodigestion is sought by the administration of proteolytic enzyme inhibitors such as gabexate mesylate, camostat mesylate, nafamostat mesylate, urinastatin, and aprotinin. The treatment of chronic pancreatitis consists of therapies analogous to that of acute pancreatitis in relapsing episodes involving abdominal pain and prohibition of alcohol intake and restriction of fat-rich food in remissions. The protease inhibitors in use today for the pharmacotherapy of pancreatitis are only effective in relieving some of the symptoms of pancreatitis and have various side effects, thus being not clinically satisfactory enough.
Meanwhile, the list of therapeutic drugs for pancreatitis under development today includes several compounds such as loxiglumide, which is a cholecystokinin antagonist, and FK480, which is a protease inhibitor. Furthermore, it has been reported that the antiulcer compound irsogladine maleate 2,4-diamino-6-(2,5-dichlorophenyl)-1,3,5-triazine maleate!, which is structurally akin to the compound of the invention, proved efficacious in an animal model of cerulein (hereinafter referred to briefly as Cn)-induced acute pancreatitis (the Proceedings of the 36th Congress of The Japanese Society of Gastroenterology, p.266).
The inventors of the present invention discovered that the 2-amino-4-substituted amino-6-(2,5-dichlorophenyl)-1,3,5-triazine derivative according to the invention has antihepatitis activity, thus being a compound of value as a therapeutic drug for hepatitis, and already filed a patent application (WO96/04914).