When should alendronate (bisphosphonate) be started in patients with osteoporosis?

When to Start Alendronate for Osteoporosis

Start alendronate in postmenopausal women with confirmed osteoporosis (T-score ≤ -2.5 at spine, hip, or femoral neck) or in those with osteopenia (T-score -1.0 to -2.5) who have additional high fracture risk factors, and in men with primary osteoporosis confirmed by DXA scanning. 1

Patient Selection Criteria

Postmenopausal Women - Definite Indications

• T-score ≤ -2.5 at lumbar spine, femoral neck, total hip, or 1/3 radial site 1
• Prior fragility fracture (hip, spine, wrist) regardless of T-score, as 60% of osteoporotic fractures occur in patients with T-scores > -2.5 1
• FRAX 10-year risk ≥ 15% for major osteoporotic fracture or hip fracture risk at or above age-based threshold 1

Postmenopausal Women - Conditional Indications

• Osteopenia (T-score -1.0 to -2.5) with individualized fracture risk assessment showing elevated risk 1
• The American College of Physicians recommends an individualized approach for women over 65 with low bone mass, balancing benefits against harms and costs based on baseline fracture risk 1

Men with Primary Osteoporosis

• T-score ≤ -2.5 at DXA measurement sites 1
• Prior fragility fracture with low bone density 1
• Men aged 70 years and older, or aged 50-69 years with risk factors, should undergo DXA screening first 1

Glucocorticoid-Induced Osteoporosis

• Adults ≥ 40 years with moderate-to-high fracture risk receiving glucocorticoids 2
• Start at initiation of glucocorticoid treatment lasting > 3 months in postmenopausal women and men aged > 50 years 2

Screening Before Treatment Initiation

Required Assessments

• DXA scan of lumbar spine, femoral neck, and total hip to confirm diagnosis 1
• Serum 25(OH)D levels with target ≥ 30 ng/mL before starting bisphosphonates 2
• Serum calcium to exclude hypocalcemia (alendronate is contraindicated in hypocalcemia) 2, 3
• Renal function assessment - alendronate not recommended if creatinine clearance < 35 mL/min/1.73 m² 2, 3

Correct Deficiencies First

• If 25(OH)D < 30 ng/mL: give ergocalciferol 50,000 IU weekly for 8 weeks, then recheck 2
• Ensure adequate calcium (1,000-1,200 mg/day) and vitamin D (800-1,000 IU/day) supplementation 2

Treatment Regimen

Standard Dosing

• Alendronate 70 mg once weekly for treatment of osteoporosis 2, 3
• Alendronate 35 mg once weekly for prevention in postmenopausal women with osteopenia 2
• Alendronate 5 mg daily alternative for prevention 2

Administration Requirements

• Take with at least 6-8 oz of plain water 3
• At least 30 minutes before first food, beverage, or other medication of the day 3
• Remain upright (sitting or standing) for at least 30 minutes after dosing 2

Contraindications to Starting Alendronate

• Esophageal abnormalities that delay esophageal emptying 2
• Inability to stand or sit upright for at least 30 minutes 2
• Hypocalcemia (must be corrected before starting) 2, 3
• Creatinine clearance < 35 mL/min/1.73 m² 2, 3

Evidence for Fracture Reduction

Postmenopausal Women

• Vertebral fractures reduced by 49% (pooled RR 0.51) over 12-36 months 1
• Hip fractures reduced by 33% (pooled RR 0.67) 1
• Radiographic vertebral fractures reduced by 140 per 1000 treated patients over ≥ 36 months 1
• Benefits evident within 12 months of starting treatment 4, 5

Men with Primary Osteoporosis

• Radiographic vertebral fractures reduced by 67% (RR 0.33) with zoledronic acid 1
• Bisphosphonates probably reduce radiographic vertebral fractures by 140 per 1000 treated men (low certainty evidence extrapolated from female data) 1

Duration and Reassessment

• Reevaluate need for continued therapy after 3-5 years of use 1
• Patients at low fracture risk should be considered for drug discontinuation after 3-5 years 1
• Patients at high fracture risk (prior fracture, very low BMD, high-risk medications) may benefit from longer duration 2
• After discontinuation, reassess fracture risk periodically 1

Common Pitfalls to Avoid

• Do not start without correcting vitamin D deficiency - inadequate supplementation reduces treatment efficacy 2
• Do not use in patients unable to follow administration instructions - improper dosing increases esophageal adverse events 2, 3
• Do not abruptly discontinue denosumab without considering sequential alendronate therapy to prevent rebound vertebral fractures 2
• Do not overlook renal function - accumulation occurs with impaired clearance 3