A 65-year-old male with ESRD on hemodialysis presents to the ED with weakness. ECG shows peaked T waves and a widened QRS complex. His serum potassium is 7.5 mEq/L. Which of the following is the most appropriate initial pharmacological agent to stabilize the cardiac membrane?

✓ Correct Answer: Option B

In severe hyperkalemia with ECG changes (peaked T waves, widened QRS), intravenous calcium gluconate is the most appropriate initial step. It directly antagonizes the cardiac effects of hyperkalemia, stabilizing the cardiac membrane, but does not lower potassium levels. Subsequent treatments remove potassium.