Abstract: The present invention provides an agent for prevention and/or treatment of itching comprising a substance capable of suppressing the function involved in signal transduction of GPR4 as an active ingredient. It also provides a nitrogen-containing tricyclic compound represented by the formula (I) or a quaternary ammonium salt thereof, or a pharmaceutically acceptable salt thereof; [wherein R1 represents substituted or unsubstituted lower alkyl, etc.; R2 represents hydrogen, substituted or unsubstituted lower alkyl, etc.; R3 and R4 are the same or different and each represents hydrogen, lower alkyl, etc.; n represents 0 or 1; X represents —(CH2)2—, etc.; and Y represents the formula (II); (wherein W represents CH or a nitrogen atom; Z1 and Z2 are the same or different and each represents hydrogen, substituted or unsubstituted lower alkyl, etc.; and Z3 represents hydrogen, substituted or unsubstituted lower alkyl, etc.

Abstract: An antiepileptic agent which contains either a xanthine derivative represented by the formula (I): (I) (wherein R1, R2, and R3 are the same or different and each represents hydrogen, lower alkyl, lower alkenyl, or lower alkynyl; R4 represents cycloalkyl, —(CH2)n.R5, or the formula (II); (II) and X1 and X2 are the same or different and each represents oxygen or sulfur) or a pharmacologically acceptable salt thereof as an active ingredient.