Initial Reclast Dose
For osteoporosis, administer Reclast (zoledronic acid) 5 mg as a single intravenous infusion over at least 15 minutes, given once yearly. 1, 2
Dosing by Indication
Osteoporosis (Postmenopausal or Male)
- Standard dose: 5 mg IV infusion once yearly 1, 2, 3
- The infusion must be administered over no less than 15 minutes to minimize renal toxicity and acute phase reactions 2
- This annual dosing regimen has been shown to reduce vertebral fractures by 70% and hip fractures by 41% over 3 years 4
Paget's Disease of Bone
- Single dose: 5 mg IV infusion over 15 minutes 5, 6, 7
- A single infusion produces therapeutic response in 96% of patients, with normalization of alkaline phosphatase in 88.6% 7
- Biochemical remission is maintained for at least 24 months after a single dose 5
- Re-treatment may be considered if relapse occurs, but most patients maintain response for extended periods 6
Cancer with Bone Metastases
- Dose: 4 mg IV infusion over at least 15 minutes every 3-4 weeks 8
- This is a different formulation and dose than osteoporosis treatment—do not confuse the two 2
- The 4 mg dose for cancer should never exceed this amount in a single infusion 2
Critical Pre-Treatment Requirements
Renal Function Assessment
- Measure serum creatinine and calculate creatinine clearance before the first dose 8, 2
- Contraindicated if creatinine clearance <30-35 mL/min 8, 1, 2
- For osteoporosis with CrCl 30-60 mL/min, no dose adjustment is needed for the 5 mg annual dose 8
- For cancer with bone metastases and CrCl 30-60 mL/min, dose reduction is required per FDA labeling 8, 2
Calcium and Vitamin D Optimization
- Correct vitamin D deficiency before administration to prevent severe hypocalcemia 1
- Supplement with 500-1,000 mg calcium daily and 400-800 IU vitamin D daily during treatment 8, 1
- Measure serum calcium before infusion—do not administer if hypocalcemia is present 2
Dental Evaluation
- Perform dental examination and complete any necessary invasive dental work before initiating therapy 8, 1
- This reduces the risk of osteonecrosis of the jaw (ONJ), which occurs in 0.06-2% of patients depending on dose and duration 1, 2
- The risk is lower with the 5 mg annual osteoporosis dose (0.8-2%) compared to the 4 mg monthly cancer dose 1
Hydration
- Ensure adequate hydration before infusion, particularly in patients with hypercalcemia of malignancy 2
- Avoid loop diuretics until patient is adequately rehydrated 2
Contraindications to Initial Dosing
- Hypersensitivity to zoledronic acid or any bisphosphonate 2
- Creatinine clearance <30-35 mL/min 8, 1, 2
- Uncorrected hypocalcemia 1, 2
- Pregnancy or lactation 1
Monitoring Before First Dose
- Serum creatinine and creatinine clearance calculation 8, 2
- Serum calcium, phosphate, magnesium 8, 2
- Complete blood count (hemoglobin/hematocrit) 8
- Vitamin D status (25-hydroxyvitamin D level) 1
- Dental assessment completed 8, 1
Common Pitfalls to Avoid
- Never infuse faster than 15 minutes—this significantly increases risk of acute phase reactions and renal toxicity 1, 2
- Do not use the 4 mg cancer dose for osteoporosis—the approved osteoporosis dose is 5 mg annually 2
- Do not administer without correcting vitamin D deficiency first—this can cause severe, symptomatic hypocalcemia 1
- Do not skip renal function assessment—renal deterioration can progress to dialysis-requiring renal failure 2
- Do not combine with Reclast if patient is already on zoledronic acid for cancer—these contain the same active ingredient 2
Expected Acute Side Effects After First Dose
- Acute phase reaction occurs in 25-40% of patients within first 3 days, including flu-like symptoms, fever, myalgia, and arthralgia 1
- These symptoms typically resolve within 4 days and decrease with subsequent annual infusions 1
- This is NOT an indication to discontinue therapy—it is expected and self-limiting 1
- Premedication with acetaminophen may reduce symptom severity 1