What is the primary monitoring parameter for a patient taking diltiazem-SR?

• A. Blood glucose level
• B. Oxygen saturation
• C. Blood pressure
• D. Serum potassium

Answer: (C)

Monitoring blood pressure is the primary concern with diltiazem-SR. This calcium channel blocker lowers blood pressure by relaxing blood vessels and can also slow the heart rate. Because hypotension can compromise organ perfusion, regularly measuring BP—especially after starting therapy or adjusting the dose—helps ensure safety and guides dosing. While heart rate should also be watched for possible bradycardia, the main parameter to monitor is blood pressure. Oxygen saturation, serum potassium, and blood glucose aren’t the primary monitoring targets for this medication, since they’re not directly affected by diltiazem-SR in routine use.