An antiarrhythmic drug that should be avoided in elderly patients because of its major toxicities is:

A. lidocaine
B. quinidine
C. disopyramide
D. diltiazem

c
Rationale: Disopyramide (Norpace) should be avoided in elderly patients because of its major toxicities. Treating elderly patients who have arrhythmias is challenging because of their clearances of certain drugs, changes in hemodynamic re-serve, severe coronary disease, and electrolyte disturbances.