1,6-Dimethyl-4-oxo-1,6,7,8,9,9a-hexahydro-4H-pyrido(1,2-a)- pyrimidine-3-carboxamide (Ch-127) protects against the intestinal damage in rats caused by two weeks' daily administration of indomethacin.

1,6-Dimethyl-4-oxo-1,6,7,8,9,9a-hexahydro-4H-pyrido 1,2-a pyrimidine-3-carboxamide (Ch-127) significantly inhibited the intestinal ulceration induced by a single dose of indomethacin (15 mg/kg p.o.). Moreover, indomethacin produced 75% lethality in the dose of 3.5 mg/kg p.o. administered daily for 2 weeks. The concurrent daily administration of Ch-127 (50 mg/kg p.o. +25 mg/kg s.c.) with indomethacin prevented the gastrointestinal mucosa from histologically detectable changes, and none of the animals died. The 80% lethality following the daily administration of naproxen (60 mg/kg p.o.) for two weeks was also significantly decreased by combining it with Ch-127 (50 mg/kg p.o.).