Final answer:
The nurse should administer Amiodarone (Cordarone) to the client with myocardial ischemia experiencing frequent early, wide ventricular complexes.
Step-by-step explanation:
The medication that the nurse should administer for a client with myocardial ischemia who is experiencing frequent early, wide ventricular complexes seen on the cardiac monitor is Amiodarone (Cordarone). Amiodarone is a potassium channel blocker that is used to treat abnormal electrical activity in the heart, specifically cardiac dysrhythmias. By impeding the movement of potassium ions through voltage-gated potassium channels, amiodarone helps stabilize the heart's electrical rhythm and prevent the occurrence of ventricular complexes.