Patent ID: 8101618

Claim:
A compound of the formula (I): wherein: R 1 represents a branched lower alkyl group having from 3 to 9 carbon atoms; R 2 represents pyridyl; R 3 is a 5-membered heteroaryl group having, in the ring, from 1 to 4 hetero atoms selected from a group consisting of a nitrogen atom, a sulfur atom and an oxygen atom, in which at least one hetero atom is a nitrogen atom, which is unsubstituted or substituted with a substituent selected from a substituent group α; R 4 represents a hydrogen atom or a lower alkyl group, wherein the lower alkyl group may be substituted with a halogen atom; X 1 is an oxygen atom; X 2 represents an oxygen atom or a single bond; m indicates an integer of from 0 to 4; substituent group α is selected from: a lower alkoxycarbonyl group, a lower alkylsulfanyl group, a lower alkyl group optionally substituted with a halogen atom, a lower alkoxy group or a hydroxy group, a hydroxy group, a cycloalkyl group, an amino group, an oxo group, a mono-lower alkylamino group and a di-lower alkylamino group; or a pharmaceutically acceptable salt thereof.