The invention provides the following compound (I): ##STR00001## wherein R.sup.1 is methoxy group, hydroxyl group or hydrogen atom; R.sup.2 is hydrogen atom, C.sub.1-4 alkyl group, C.sub.1-4 alkylcarbonyl group or arylcarbonyl group; D is a group of the following formula (A), (B), or (C). ##STR00002## The compound is useful as a medicament for treating neuropathic pain or pain caused by various diseases such as rheumatoid arthritis and osteoarthritis, and inflammation.