The present invention is directed to quinazolinone compounds of the formula I: ##STR00001## wherein R.sup.1, R.sup.2, R.sup.3, X.sup.1, X.sup.2 X.sup.3 are defined herein. These compounds are antagonists of T-type calcium channels, and are useful in the treatment or prevention of disorders and diseases in which T-type calcium channels are involved. The invention is also directed to pharmaceutical compositions comprising these compounds and the use of these compounds and compositions in the prevention or treatment of such diseases in which T-type calcium channels are involved.