A new analgesic has been developed for T-type calcium channels as therapeutic targets.The present invention provides a T-type calcium channel inhibitor which is a compound represented by formula (1):whereineach of R1 and R2 independently represents —；H or —；OH；R3 represents —；OH；R4 represents —；OH or —；H；R5 represents a straight or branched alkyl or cycloalkyl-alkyl group having one to ten carbon atoms or a straight or branched alkenyl or cycloalkyl-alkenyl group having two to ten carbon atoms,or a pharmaceutically acceptable salt or solvate thereof.The present invention also provides this T-type calcium channel inhibitor, a medicament containing the T-type calcium channel inhibitor, and a therapeutic or prophylactic agent for a disease having an effective T-type calcium channel inhibitory action.
