Abstract: A pyrrolopyridazine compound having the formula (I) or a pharmaceutically acceptable salt thereof: wherein, R1 is a C2-C6 alkenyl group, a halogeno C2-C6 alkenyl group, a C3-C7 cycloalkyl group which may be optionally substituted or a C3-C7 cycloalkyl- C1-C6 alkyl group which may be optionally substituted. R2 is a C1-C6 alkyl group. R3 is a hydroxymethyl group, a C2-C6 aliphatic acyloxymethyl group, a C6-C10 arylcarbonyloxymethyl group which may be optionally substituted, a C1-C6 alkoxycarbonyloxymethyl group, a formyl group, a carboxyl group, a C1-C6 alkoxycarbonyl group or a C6-C10 aryloxycarbonyl group which may be optionally substituted. R4 is a C6-C10 aryl group which may be optionally substituted. A is an imino group, an oxygen atom or a sulfur atom. These compounds exhibit excellent gastric acid secretory inhibition activity and gastric mucous membrane protection activity etc. They are useful for prevention or treatment of ulcerative diseases and for Helicobacter pylori infections.

Abstract: A pyrrolopyridazine compound having the formula (I) or a pharmaceutically acceptable salt thereof: 1

Abstract: An optically active pyrrolopyridazine compound of the formula (I) or a pharmaceutically acceptable salt thereof: wherein R1 is alkyl; R2 and R3 are each independently alkyl; R4 is optionally substituted aryl; and A is imino, oxygen or sulfur. The pyrrolopyridazine compound or pharmaceutically acceptable salts thereof of the present invention exhibit excellent gastric acid secretory inhibition activity and gastric mucous membrane protection activity, as well as excellent antibacterial activity against Helicobacter pylori. They are useful medicines and are particularly useful for treating or preventing ulcerative diseases.

Abstract: An optically active pyrrolopyridazine compound of the formula (I) or a pharmaceutically acceptable salt thereof: 1

Abstract: Pyrrolopyridazine derivatives having the general formula. ##STR1## In the above formula, R.sup.1 represents a C.sub.2 -C.sub.6 alkenyl-group, a halogeno-C.sub.2 -C.sub.6 -alkenyl group, a C.sub.6 -C.sub.10 aryl-C.sub.2 -C.sub.6 -alkenyl group, a C.sub.2 -C.sub.6 alkynyl group, a C.sub.3 -C.sub.7 cycloalkyl group, a C.sub.3 -C.sub.7 cycloalkyl-C.sub.1 -C.sub.6 -alkyl group, a C.sub.5 -C.sub.7 cycloalkenyl-C.sub.1 -C.sub.6 -alkyl group or a halogeno-C.sub.1 -C.sub.6 -alkyl group; R.sup.2 and R.sup.3 are the same or different and each represents a hydrogen atom, a C.sub.1 -C.sub.6 alkyl group or a C.sub.6 -C.sub.10 aryl group; R.sup.4 represents a hydrogen atom or a C.sub.1 -C.sub.6 alkyl group; R.sup.5 represents a C.sub.6 -C.sub.