Inotropics (drugs used to increase the pumping ability of the heart) and antiarrhythmics may need TDM. The cardiac glycoside inotropics digoxin and digitoxin have narrow therapeutic windows. Overdose can cause vomiting, diarrhea, confusion, visual disturbances, and cardiac arryhthmias.

Examples of cardiac medications that are monitored by TDM include:

• Digoxin
• Digitoxin
• Procainamide
• N-Acetylprocainamide (NAPA) -the metabolite of procainamide
• Quinidine