ClinCalc Pro
Menu
Calculators Drugs Pathways AI Dx Donate Get the App
Bisphosphonate Pregnancy: C

Alendronic Acid Weekly

Brand names: Fosamax Once Weekly, Binosto

Adult dose

Dose: 70 mg once weekly
Route: oral
Frequency: once weekly
Max: 70 mg/week
Take on empty stomach with full glass of water (200 mL); remain upright for 30 min; no food/drink/medication for 30 min; avoid bedtime dosing

Paediatric dose

Route:
Not licensed in children; specialist use only for osteogenesis imperfecta

Dose adjustments

Renal

Avoid if eGFR <35 ml/min

Hepatic

No dose adjustment required

Clinical pearls

  • Most prescribed bisphosphonate in UK; once-weekly dosing improves adherence vs. daily
  • Drug holiday: after 5 years of use, reassess fracture risk — holiday may be appropriate for low-risk patients
  • Jaw osteonecrosis risk increases with IV bisphosphonates for cancer; oral bisphosphonates for osteoporosis carry much lower risk

Contraindications

  • Oesophageal disorders (stricture, achalasia, inability to sit upright)
  • eGFR <35 ml/min
  • Hypocalcaemia

Side effects

  • Oesophageal reactions (oesophagitis, erosions — severe if position not maintained)
  • Abdominal pain
  • Jaw osteonecrosis (rare, mainly IV bisphosphonates)
  • Atypical femoral fractures (long-term)
  • Hypocalcaemia

Interactions

  • Calcium/antacids/iron (reduce absorption — give 30 min before)
  • NSAIDs/aspirin (GI irritation)
  • PPIs reduce efficacy slightly

Monitoring

  • Bone density (DEXA) every 2 years
  • Dental review before initiation
  • Calcium and vitamin D (supplement before starting)

Reference: BNFc; BNF 86; NICE NG187; RCP guidelines. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

Calculators
Drugs
Pathways