The ring-fused heterocyclic compound or a pharmaceutically acceptable salt thereof according to the present invention has a T-type calcium channel regulatory effect, and is useful, for example, as a medicament for treating and/or preventing pruritus. The present invention provides a ring-fused heterocyclic compound represented by the following general formula (I) or a pharmaceutically acceptable salt thereof and the like which has a T-type calcium channel regulatory effect and is useful as a therapeutic and/or preventive agent for pruritus, and the like. ##STR00001##
[wherein, R.sup.1 represents optionally substituted lower alkyl and the like, R.sup.2 represents optionally substituted lower alkyl and the like, R.sup.3 represents the formula (II): ##STR00002##
(wherein, n represents 0 or 1, R.sup.3a represents a hydrogen atom and the like, R.sup.3b represents a hydrogen atom and the like, and R.sup.3c represents a hydrogen atom and the like) and the like, Q represents a hydrogen atom and the like, and W.sup.1 represents a nitrogen atom and the like, W.sup.2 represents a nitrogen atom and the like].

The present invention is directed to cyclopentapyrrole, furopyrrole and azabicycloheptane compounds which are agonists of orexin receptors. The present invention is also directed to uses of the compounds described herein in the potential treatment or prevention of neurological and psychiatric disorders and diseases in which orexin receptors are involved. The present invention is also directed to compositions comprising these compounds. The present invention is also directed to uses of these compositions in the potential prevention or treatment of such diseases in which orexin receptors are involved.

The present invention is directed to cyclopentapyrrole, furopyrrole and azabicycloheptane compounds which are agonists of orexin receptors. The present invention is also directed to uses of the compounds described herein in the potential treatment or prevention of neurological and psychiatric disorders and diseases in which orexin receptors are involved. The present invention is also directed to compositions comprising these compounds. The present invention is also directed to uses of these compositions in the potential prevention or treatment of such diseases in which orexin receptors are involved.