The present invention provides a pharmaceutical composition for use as an NPY Y5 receptor antagonist comprising a compound of the formula (I): ##STR00001## wherein R.sup.1 is lower alkyl, cycloalkyl or the like, R.sup.2 is hydrogen, lower alkyl or the like, n is 1 or 2, X is lower alkylene, lower alkenylene, arylene, cycloalkylene or the like, Y is CONR.sup.7, CSNR.sup.7, NR.sup.7CO, NR.sup.7CS or the like, Z is lower alkyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl or the like and R.sup.7 is hydrogen or lower alkyl, prodrug, pharmaceutically acceptable salt or solvate thereof.