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Bisphosphonate (bone resorption inhibitor) Pregnancy: Not applicable (post-menopausal use; avoid in women of childbearing age).

Alendronic Acid (Alendronate)

Brand names: Fosamax, Binosto

Adult dose

Dose: Osteoporosis: 70 mg once weekly; Paget's disease: 40 mg daily for 6 months
Route: Oral (strict administration requirements — see notes)
Frequency: Once weekly (osteoporosis)
Max: 70 mg/week (osteoporosis)
Osteoporosis prevention/treatment: 70 mg once weekly. Take in the morning after overnight fast with full glass of water (200 mL minimum). Remain upright for at least 30 min after and before eating/drinking/other medication. Do not lie down. Take calcium and Vit D supplements (2 hours apart from alendronate).

Paediatric dose

Route: Not applicable
Frequency: Not licensed in children
Max: Not applicable
Not licensed for osteoporosis in children. Pamidronate IV used by specialist for childhood osteoporosis (OI).

Dose adjustments

Renal

Avoid if eGFR <35 mL/min (accumulation; no clinical data).

Hepatic

No dose adjustment required.

Clinical pearls

  • Administration technique critical — oesophageal ulceration is preventable with correct technique
  • Drug holiday: review at 5 years — patients with T-score >-2.5 may safely stop
  • Dental care: before starting, dental review and any extractions completed (ONJ risk reduced)
  • Atypical femoral fracture: pain in thigh/groin — X-ray, consider drug holiday
  • Calcium 1000 mg/day and Vitamin D 800 IU/day supplementation essential alongside

Contraindications

  • Oesophageal abnormalities (stricture, achalasia — unable to sit upright)
  • Hypocalcaemia (treat before starting)
  • Unable to sit or stand upright for 30 min
  • eGFR <35 mL/min

Side effects

  • Oesophageal irritation and ulceration (if administration instructions not followed)
  • Abdominal pain and dyspepsia
  • Osteonecrosis of the jaw (rare — especially with IV bisphosphonates; risk with oral after >3 years)
  • Atypical femoral fractures (long-term use >5 years)
  • Hypocalcaemia (transient)

Interactions

  • Calcium, antacids — chelate alendronate; take 2 hours apart
  • NSAIDs — increased risk of GI irritation
  • Aspirin — increased GI effects

Monitoring

  • DEXA at 2–5 years
  • Serum calcium and Vit D
  • Renal function annually
  • Jaw pain

Reference: BNFc; BNF; NICE CG146 Osteoporosis; NOGG Guidelines 2021. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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