<p>Patients with reduced levels of CYP2D6 isoenzyme, congenital long QT syndrome or history of cardiac arrhythmias; severe CNS depression or comatose states of any cause; hypertensive or hypotensive heart disease of extreme degree. Concomitant use with drugs that prolong QTc interval, CYP2D6 isoenzyme inhibitors and drugs which reduce thioridazine clearance by other mechanisms.</p>