Provided is a compound useful as a therapeutic drug for pain and inflammation caused by various pathological conditions such as neuropathic pain and rheumatoid arthritis. The compound of the formula (I) or a salt thereof [wherein R1 is a methyl group or a hydrogen atom, R2 represents a hydrogen atom, an alkyl group, an alkylcarbonyl group or an aryl carbonyl group, A represents a cycloalkyl group, a cycloalkenyl group, an aryl group or a heteroaryl group (each group may be substituted with a substituent selected from the group consisting of alkyl, alkenyl, cycloalkyl and halogen), n and m each represent an integer of 1, 2 or 3, and p represents an integer of 0, 1, 2 or 3].