Bisphosphonate — Oral (Weekly) Pregnancy: Contraindicated — bisphosphonates accumulate in bone for years

Alendronic Acid (Rheumatology — Osteoporosis)

Brand names: Fosamax, Binosto

Adult dose

Dose: 70 mg once weekly (osteoporosis); 10 mg once daily (Paget's disease)

Route: Oral

Frequency: Once weekly (osteoporosis) or once daily (Paget's)

Max: 70 mg once weekly

CRITICAL dosing instructions: Take on an empty stomach, first thing in the morning with a full glass of plain water (not mineral water, coffee or juice). Remain UPRIGHT (sitting or standing) for at least 30 minutes after taking. Do not eat, drink (except water) or take other medications for 30 minutes. Never give at bedtime. Alendronate + calcium + vitamin D supplementation required.

Paediatric dose

Route:

Paediatric osteoporosis — seek specialist paediatric bone health opinion; off-label use

Dose adjustments

Renal

Avoid if eGFR <35 mL/min — accumulates in bone; not renally cleared but accumulates

Hepatic

No dose adjustment required

Clinical pearls

MHRA 2008: Severe oesophageal reactions including oesophageal ulcers, strictures, and oesophageal perforation — patients must be counselled about the 30-minute upright rule and stop alendronate immediately if they develop dysphagia, odynophagia, or chest pain
MHRA 2010: Oesophageal cancer — rare reports of oesophageal cancer in bisphosphonate users, though causality not proven; absolute risk very small; benefits far exceed risks in osteoporosis management
FIT trial (NEJM 1996): 10 mg daily alendronate reduced vertebral fracture risk by 47% and hip fracture risk by 51% in women with prior vertebral fracture
First-line oral bisphosphonate for glucocorticoid-induced osteoporosis (GIOP) — rheumatology setting: all patients on prednisolone ≥5 mg for ≥3 months should receive bone protection
Drug holiday: consider after 5–10 years of oral bisphosphonate use; higher atypical femoral fracture risk with duration; low-risk patients (T-score >−2.5) may take 1–2 year holiday with DXA monitoring

Contraindications

Oesophageal disorders (stricture, dysmotility, achalasia)
Inability to sit or stand upright for 30 minutes
Hypocalcaemia
eGFR <35 mL/min

Side effects

Oesophageal irritation, ulceration, and erosions — most important
GI symptoms — abdominal pain, dyspepsia, nausea
Hypocalcaemia
Bone, joint and muscle pain (diffuse — may be severe)
Osteonecrosis of the jaw (rare — lower risk than IV bisphosphonates)
Atypical femoral fractures (after long-term use ≥5 years)

Interactions

Calcium, antacids, iron — reduce absorption; must be separated by ≥30 minutes (or taken 30 min after alendronate in practice — alendronate is always first)
NSAIDs — increased GI mucosal damage; caution with concomitant use

Monitoring

Serum calcium and vitamin D at baseline
Renal function and eGFR before starting
DXA scan every 2 years
Dental review before starting
Thigh/hip pain — atypical femoral fractures

Reference: BNFc; BNF 90; FIT Trial (NEJM 1996); MHRA DSU 2008 (oesophageal reactions); MHRA 2010 (oesophageal cancer); NICE TA204; NOGG Osteoporosis Guidelines. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways