What is the recommended treatment for postmenopausal osteoporosis?

Treatment of Postmenopausal Osteoporosis

Oral bisphosphonates, particularly alendronate, are strongly recommended as first-line treatment for postmenopausal osteoporosis due to their proven efficacy in reducing fracture risk, favorable safety profile, and low cost. 1

First-Line Treatment Options

Oral Bisphosphonates

• Alendronate (Preferred)

  • Dosing: 5 mg daily or 35 mg weekly for prevention; 10 mg daily or 70 mg weekly for treatment 2, 3
  • Effectively reduces risk of vertebral, non-vertebral, and hip fractures 1
  • Should be taken with plain water in the morning after waking and at least 30 minutes before first food or drink 3

• Risedronate

  • Dosing: 5 mg daily, 35 mg weekly, 75 mg on two consecutive days monthly, or 150 mg monthly 2, 4
  • Delayed-release formulation (35 mg weekly) can be taken immediately following breakfast 4
  • Patients should remain upright for 30 minutes after taking 4

• Ibandronate

  • Dosing: 2.5 mg daily, 150 mg monthly oral, or 3 mg IV every three months 2

Alternative Treatment Options

For patients who cannot tolerate oral bisphosphonates or have contraindications:

1. Zoledronic acid (Reclast)

   • Dosing: 5 mg IV annually for treatment; every two years for prevention 2, 1
   • Contraindicated in patients with hypocalcemia, creatinine clearance < 35 mL/min, or acute renal impairment 2

2. Denosumab (Prolia)

   • Dosing: 60 mg subcutaneous injection every six months 2, 1
   • Particularly useful for patients with renal impairment
   • Contraindicated in hypocalcemia 2
   • Requires transition to another antiresorptive agent upon discontinuation to prevent rapid bone loss 1

3. For very high fracture risk patients:

   • Consider anabolic agents (teriparatide, romosozumab) followed by an antiresorptive agent 1
   • Teriparatide: 20 mcg SC daily 2
   • Reserved for patients with prior vertebral fractures, T-score ≤ -3.5, or recent hip fracture 1

Treatment Duration and Monitoring

• Initial treatment duration typically 5 years 1
• After 5 years, reassess fracture risk to determine whether to continue or discontinue treatment 1
• Longer treatment may be considered for patients who remain at high risk 1
• Monitor with bone density measurements (DXA) every 1-3 years 1
  • More frequent monitoring (annually) for patients on glucocorticoids or with previous fractures

Calcium and Vitamin D Supplementation

• All patients should receive calcium (1000-1200 mg/day) and vitamin D (800 IU/day) supplementation 1, 4
• Take calcium supplements, antacids, magnesium-based supplements or laxatives at a different time of day from bisphosphonates 4

Important Precautions and Side Effects

• Oral bisphosphonates:

  • Common side effects: mild upper GI symptoms (abdominal pain, dyspepsia, acid regurgitation) 1, 5
  • Patients should remain upright for 30 minutes after taking to reduce risk of esophageal irritation 4
  • Weekly dosing regimens improve adherence compared to daily dosing 6, 7

• Rare but serious side effects:

  • Osteonecrosis of the jaw
  • Atypical femoral fractures 1
  • Monitor for thigh or groin pain, which may indicate potential atypical femoral fracture 1

Fracture Risk Assessment

Use FRAX risk assessment tool to evaluate fracture risk:

• High Risk: BMD T-score ≤-2.5 but >-3.5 OR FRAX 10-year risk of major osteoporotic fracture ≥20% but <30% or hip fracture ≥3% but <4.5% 1
• Very High Risk: Prior osteoporotic fracture OR BMD T-score ≤-3.5 OR FRAX 10-year risk of major osteoporotic fracture ≥30% or hip ≥4.5% 1

Clinical Pearls

• Combination therapy is not recommended 2
• Bisphosphonates have shown sustained efficacy in clinical trials: alendronate up to 10 years and risedronate up to 7 years 8
• Once-weekly formulations of bisphosphonates have comparable efficacy to daily dosing with improved adherence 6, 7, 8
• Delayed-release risedronate can be taken with food, which may improve tolerability and convenience 7