This invention provides a compound of the formula (I): wherein R.sup.1 represents a (C.sub.1-C.sub.6)alkyl group; R.sup.2 represents a hydrogen atom, a halogen atom, a hydroxy group, a (C.sub.1-C.sub.6) alkyl group or a (C.sub.1-C.sub.6) alkoxy group; R.sup.3, R.sup.4, R.sup.5 and R.sup.6 each independently represents a hydrogen atom, a (C.sub.1-C.sub.6) alkyl, or a halogen atom; R.sup.7 represents a hydrogen atom, a halogen atom, a hydroxy group, a (C.sub.1-C.sub.6) alkyl group optionally substituted with a piperidino group, a (C-.sub.1-C.sub.6)alkoxy group optionally substituted with a 3-7 membered cycloalkyl ring, a hydroxy(C.sub.1-C.sub.6)alkoxy group, a (C.sub.1-C.sub.6)alkoxy-(C.sub.1-C.sub.6)alkyl group, a (C.sub.1-C.sub.6)alkoxy-(C.sub.1-C.sub.6)alkoxy group, a halo (C.sub.1-C.sub.6)alkyl group, a (C.sub.1-C.sub.6)alkylthio group, a (C.sub.1-C.sub.6)alkylsulfinyl group or a (C.sub.1-C.sub.6)alkylsulfonyl group; R.sup.5 represents a (C.sub.1-C.sub.6)alkyl group, a halo(C.sub.1-C.sub.6)alkyl group, a (C.sub.1-C.sub.6)alkoxy group, a hydroxy(C.sub.1-C.sub.6)alkoxy group, a (C.sub.1-C.sub.6)alkoxy-(C.sub.1-C.sub.6)alkyl group or a (C.sub.1-C.sub.6)alkoxy-(C.sub.1-C.sub.6)alkoxy group; or R.sup.7 and R.sup.8, when adjacent to each other, taken together with the carbon atoms to which they are attached form a 5-8 membered carbocyclic or heterocyclic ring, wherein the carbocyclic ring or the heterocyclic ring is unsubstituted or substituted with one or more substituents selected from the group consisting of a hydroxy group, a (C.sub.1-C.sub.6)alkyl group, a (C.sub.1-C.sub.6)alkoxy group and a hydroxy(C.sub.1-C.sub.6)alkyl group; and R.sup.9 represents a hydrogen atom or a halogen atom; or a pharmaceutically acceptable salt or solvate thereof. These compounds are useful for the treatment of disease conditions caused by overactivation of VR1 receptor, such as pain or the like in mammalian. The present invention also provides a pharmaceutical composition comprising the compound of formula (I).