How to Initiate Alendronate and Required Laboratory Testing
Initiate alendronate 70 mg once weekly after confirming osteoporosis by DXA scan, checking serum 25-hydroxyvitamin D levels and correcting deficiency to ≥30 ng/mL, ensuring serum calcium is normal, and assessing renal function (avoid if GFR <35 mL/min/1.73 m²). 1, 2
Pre-Treatment Laboratory Testing
Essential Labs Before Starting Alendronate
Serum 25-hydroxyvitamin D level: Must be checked and corrected before initiating bisphosphonates to prevent hypocalcemia 1
Serum calcium: Must be normal before starting; alendronate is contraindicated in hypocalcemia 1, 2
Renal function (GFR/creatinine clearance): Assess before initiation 1
- Do not use alendronate if GFR <35 mL/min/1.73 m² 1
DXA scan: Required to confirm osteoporosis diagnosis before starting therapy 1
- Measure lumbar spine, femoral neck, and total hip 1
Patient Selection Criteria
Who Should Receive Alendronate
Postmenopausal women with T-score ≤-2.5 at lumbar spine, femoral neck, total hip, or 1/3 radial site 1
Prior fragility fracture regardless of T-score (60% of osteoporotic fractures occur in patients with T-scores >-2.5) 1
Men with primary osteoporosis and T-score ≤-2.5 at DXA measurement sites 1
Cancer survivors with osteoporosis (T-score ≤-2.5) or 10-year fracture probability ≥20% for major osteoporotic fractures or ≥3% for hip fractures based on FRAX 3
Glucocorticoid-induced osteoporosis: Adults ≥40 years with moderate-to-high fracture risk receiving glucocorticoids 1
Dosing Regimen
Standard Treatment Dose
Alendronate 70 mg once weekly is the recommended regimen 1, 2, 4, 5
- This once-weekly dosing is therapeutically equivalent to 10 mg daily, with mean lumbar spine BMD increases of 5.1-7.4% over 1-2 years 4, 5
- Once-weekly dosing provides better convenience and may enhance adherence compared to daily dosing 4, 5
- The 70 mg weekly dose (seven times the daily dose) provides continuous inhibition of bone resorption because osteoclast activity requires 2-3 weeks for completion 6, 7
Alternative Dosing Options
- Prevention of osteoporosis: 35 mg once weekly or 5 mg daily 1
- Combination product: Alendronate/cholecalciferol 70 mg plus 2,800-5,600 IU vitamin D once weekly 1
Mandatory Concurrent Supplementation
Calcium and Vitamin D Requirements
All patients must receive adequate calcium and vitamin D supplementation to optimize therapeutic outcomes and prevent hypocalcemia 1
Inadequate supplementation during alendronate therapy reduces treatment efficacy, as most clinical trials included 500-1,000 mg calcium and 400-800 IU vitamin D daily 1
Contraindications to Check Before Initiating
- Esophageal abnormalities that delay esophageal emptying 1
- Inability to stand or sit upright for at least 30 minutes 1
- Hypocalcemia (must be corrected before starting) 1, 2
- GFR <35 mL/min/1.73 m² 1
- Hypersensitivity to any component 1
Monitoring During Therapy
Follow-Up Laboratory Testing
- Follow-up DXA scan after 1 year of therapy is recommended by the International Society for Clinical Densitometry 3
- Serum 25-hydroxyvitamin D: Check at the same time as DXA scans for patients requiring monitoring 3
- Biochemical markers of bone turnover: Not recommended for monitoring response to therapy 3
Treatment Duration Considerations
- Reevaluate need for continued therapy after 3-5 years of use 1
- Low fracture risk patients: Consider drug discontinuation after 3-5 years 1
- High fracture risk patients: May benefit from longer duration therapy 1
- After >5 years: Consider drug holidays or dose reduction, as fracture protection may persist for up to 5 years after stopping 1
Administration Instructions
Alendronate must be taken in the fasting state with water at least 30 minutes before consuming food or beverages, and patients must remain upright for at least 30 minutes after dosing to minimize esophageal irritation risk 1, 6, 8