What is Fosamax (alendronate)?

What is Fosamax (Alendronate)?

Fosamax (alendronate) is a first-line bisphosphonate medication that inhibits osteoclast-mediated bone resorption, increases bone mineral density, and reduces fracture risk in patients with osteoporosis. 1

Mechanism of Action

Alendronate works through a specific mechanism:

• Binds preferentially to bone hydroxyapatite at sites of bone resorption, particularly under osteoclasts 1
• Inhibits osteoclast activity without interfering with osteoclast recruitment or attachment 1
• Reduces bone turnover by decreasing the number of remodeling sites 1
• Allows bone formation to exceed bone resorption at these remodeling sites, leading to progressive gains in bone mass 1

Formulations and Dosing

Fosamax is available in several formulations:

• For prevention of osteoporosis: 5 mg daily or 35 mg weekly tablets/solution 2
• For treatment of osteoporosis: 10 mg daily or 70 mg weekly tablets/solution 2
• Combination product: Fosamax Plus D (alendronate with vitamin D) - 70 mg plus 2,800 IU or 5,600 IU weekly 2

The once-weekly dosing regimen (70 mg) is therapeutically equivalent to the daily regimen (10 mg) and offers greater convenience 3.

Clinical Efficacy

Alendronate has demonstrated significant clinical benefits:

• Produces sustained increases in bone mineral density (BMD) in postmenopausal women with or without osteoporosis 4
• Reduces the risk of vertebral fractures by 47-56% in postmenopausal women 4
• Reduces the risk of hip fractures by approximately 50% 4, 5
• Reduces the risk of all clinical fractures by about 30% 5
• Histomorphometric analyses show that alendronate does not impair bone quality 4

Indications

Fosamax is indicated for:

1. Treatment of osteoporosis in postmenopausal women 2
2. Treatment of osteoporosis in men 2
3. Prevention of osteoporosis in postmenopausal women 2
4. Treatment of glucocorticoid-induced osteoporosis 4

Contraindications

Alendronate should not be used in patients with:

• Abnormalities of the esophagus 2
• Inability to stand or sit upright for at least 30 minutes 2
• Hypocalcemia 2
• Hypersensitivity to any component of the product 2
• Patients at increased risk of aspiration should not receive alendronate solution 2

Administration Instructions

Proper administration is crucial to minimize adverse effects:

• Take on an empty stomach with plain water first thing in the morning 6
• Remain upright (sitting or standing) for at least 30 minutes after taking 2
• Wait at least 30 minutes before consuming food, beverages, or other medications 3

Adverse Effects

Common adverse effects include:

• Upper GI symptoms: abdominal pain, nausea, dyspepsia, acid regurgitation 6
• Musculoskeletal pain 6

Rare but serious adverse effects include:

• Osteonecrosis of the jaw 2
• Atypical femoral fractures 2, 7
• Esophageal adverse events (including esophagitis and esophageal ulcers) 6

Place in Therapy

According to current guidelines:

• Bisphosphonates, including alendronate, are recommended as first-line therapy for osteoporosis 2
• The American College of Physicians strongly recommends bisphosphonates to reduce fracture risk in women with known osteoporosis (high-quality evidence) 2
• For men with osteoporosis, bisphosphonates are suggested as initial treatment (conditional recommendation; low-quality evidence) 2
• Treatment duration is typically 5 years, after which continuation should be reassessed 2, 8

Monitoring

• Bone mineral density monitoring is not needed during the initial 5-year treatment period 8
• Adequate calcium (1000-1200 mg) and vitamin D (600-800 IU) supplementation is essential for patients on bisphosphonate therapy 8

Fosamax has been a cornerstone in osteoporosis treatment since its FDA approval in 1995, preventing millions of fractures worldwide 7.