Compounds and methods for treating diseases mediated by a P2X.sub.3 and/or
a P2X.sub.2/3 receptor antagonist, the methods comprising administering
to a subject in need thereof an effective amount of a compound of formula
(I): ##STR00001## wherein D, X, R.sup.1, R.sup.2, R.sup.3, R.sup.4,
R.sup.5, R.sup.6, R.sup.7 and R.sup.8 are as defined herein.