What is the recommended treatment and dosage for Fosamax (alendronate) in patients with osteoporosis?

Fosamax (Alendronate) Treatment for Osteoporosis

Recommended Dosing

For treatment of established osteoporosis in postmenopausal women and men, administer alendronate 70 mg once weekly, which is therapeutically equivalent to 10 mg daily dosing while offering superior convenience and adherence. 1, 2, 3

Standard Treatment Regimens

• Osteoporosis treatment: 70 mg once weekly (preferred) or 10 mg daily 1, 2, 3
• Osteoporosis prevention in postmenopausal women: 35 mg once weekly or 5 mg daily 1, 2, 3
• Combination formulation: Alendronate 70 mg plus vitamin D (2,800-5,600 IU) once weekly is available and recommended 2
• Glucocorticoid-induced osteoporosis: 5 mg daily (or 70 mg weekly based on treatment equivalence) 4, 3

Special Population Considerations

Men with osteoporosis: Use identical dosing to postmenopausal women—70 mg once weekly or 10 mg daily—as efficacy is equivalent regardless of whether osteoporosis is hypogonadal or idiopathic in origin 3

Patients on androgen deprivation therapy (ADT): Alendronate 70 mg weekly is recommended when 10-year fracture probability reaches ≥3% for hip fracture or ≥20% for major osteoporotic fracture using the FRAX algorithm 4

Critical Contraindications and Precautions

Absolute contraindications 2:

• Esophageal abnormalities that delay esophageal emptying
• Inability to stand or sit upright for at least 30 minutes
• Hypocalcemia (must be corrected before initiating therapy)
• Renal impairment with GFR <35 mL/min/1.73 m² 1, 2

Essential Supplementation Requirements

All patients must receive adequate calcium and vitamin D supplementation to optimize treatment efficacy and prevent hypocalcemia 4, 2:

• Calcium: 1,000-1,200 mg daily 4, 2
• Vitamin D: 800-1,000 IU daily 4, 2
• Check serum 25(OH)D levels before initiating therapy, with target levels ≥30 ng/mL 2
• For vitamin D deficiency (25(OH)D <30 ng/mL): ergocalciferol 50,000 IU weekly for 8 weeks, then recheck 2

Administration Instructions

To minimize esophageal irritation and maximize absorption 2, 3:

• Take first thing in the morning after overnight fast
• Swallow with a full glass (6-8 oz) of plain water only
• Remain upright (standing or sitting) for at least 30 minutes
• Do not eat, drink, or take other medications for at least 30 minutes after dosing

Duration of Therapy and Drug Holidays

After 5 years of continuous bisphosphonate therapy, consider a drug holiday or dose reduction in patients at lower fracture risk, as fracture protection may persist for up to 5 years after discontinuation 2. However, continue therapy in high-risk patients (prior hip or vertebral fracture, very low BMD, or ongoing high-dose glucocorticoid use) 2.

Efficacy Data

The once-weekly 70 mg regimen demonstrates therapeutic equivalence to daily 10 mg dosing 3, 5:

• Lumbar spine BMD increases: 5.1% at 12 months with weekly dosing vs. 5.4% with daily dosing 3, 5
• Vertebral fracture risk reduction: 47-48% in women with existing fractures 3
• Multiple vertebral fracture reduction: 87-90% risk reduction 3
• Hip fracture reduction: 51% in women with existing vertebral fractures 3

Monitoring Recommendations

• Baseline DEXA scan before initiating therapy in patients at increased fracture risk 4
• Follow-up DEXA scan after 1-2 years of therapy to assess response 4, 6
• Serum 25(OH)D levels at baseline and periodically during therapy 2
• Biochemical markers of bone turnover are not recommended for routine monitoring 4

Common Pitfalls to Avoid

Do not prescribe alendronate to patients with GFR <35 mL/min/1.73 m², as safety and efficacy are not established in this population 1, 2

Do not initiate therapy in patients with uncorrected hypocalcemia, as bisphosphonates can further lower serum calcium 2

Do not allow patients to lie down within 30 minutes of dosing, as this significantly increases the risk of esophageal ulceration 2, 3

Do not discontinue calcium and vitamin D supplementation during alendronate therapy, as inadequate supplementation reduces treatment efficacy and increases hypocalcemia risk 2

Proton pump inhibitors (PPIs) may decrease calcium absorption and increase fracture risk—monitor patients on concurrent PPI therapy more closely 6