A 60-year-old woman has had constipation, weakness, and lethargy for the past 4 days. Three weeks ago, she was diagnosed with inoperable lobular carcinoma of the breast. Laboratory studies show:
Hemoglobin 11 g/dL
Leukocytes 8,000/μL
Sodium 141 mEq/L
Potassium 3.9 mEq/L
Calcium 15.1 mg/dL
Phosphorus 3.5 mEq/L
Albumin 4.5 g/dL
An ECG shows a short QT interval. Intravenous 0.9% saline is administered.
Which of the following is the most appropriate pharmacotherapy?
