1,4-Dihydropyridine derivatives

A compound having the formula (I):

• wherein
• R1 represents a phenyl or pyridyl group, wherein the phenyl or pyridyl group is optionally substituted with a C1 to C3 lower alkylthio group, a C1 mto C3 lower alkyloxy group, a C1 to C3 lower alkyl group, a halogen atom, or a heterocyclic group selected from the group consisting of imidzaopyridine, piperazine, imidazole, morphoine, indole, benzimidazole, indazole, thiophene, and 1H-benzotriazole, wherein the heterocyclic group is optionally substituted with a C1 to C3 lower alkyl group, a trifluoromethyl group, or a halogen atom;
• R2 represents a C1 to C5 lower alkyl group;
• R3 represents a C1 to C8 alkyl, alkenyl or alkynyl group;
• a C3 to C7 cycloalkyl or cycloalkenyl group;
• or a C1 to C4 lower alkyl group or C2 to C3 lower alkenyl group substituted with a phenyl, thienyl, furyl, cyclohexyl, naphthyl, indanyl, 1,1a,6,10b-tetrahydrodibenzo[a,e]-cyclopropac[c]ycloheptene-yl, 5H-dibenzo[a,d]cycloheptene-yl group or 10,11-dihydro-5H-dibenzo[a,d]cyclohepten-yl ring group, wherein the ring group is optionally substituted with a halogen atom, C1 to C3 lower alkyloxy group, or a C1 to C3 lower alkyloxy group substituted with a cycloalkyl or phenyl group;
• R4 represents —A—R5, wherein A represents a C3 to C5 alkynylene group having one triple bond;
• and
• R5 represents a pyridyl, quinolyl, isoquinolyl or pyrimidyl group, each of which may be optionally substituted with a C1 to C3 lower alkyl group, C1 to C3 lower alkoxy group, or a halogen atom.