Bisphosphonate (bone resorption inhibitor) Pregnancy: Should NOT be used during pregnancy — no or limited data in pregnant women, and animal studies have shown reproductive toxicity (alendronate given during pregnancy in rats caused dystocia related to hypocalcaemia). Should NOT be used during breast-feeding — it is unknown whether alendronate/metabolites are excreted in human milk and a risk to the newborn/infant cannot be excluded. Fertility: bisphosphonates are incorporated into bone matrix and released gradually over years, so there is a theoretical risk of foetal harm (predominantly skeletal) if a woman becomes pregnant after completing a course; this has not been studied.

Alendronic Acid (Alendronate)

Brand names: Fosamax, Binosto

Alendronic acid (alendronate) is an oral nitrogen-containing bisphosphonate, first-line for the treatment and prevention of osteoporosis and for glucocorticoid-induced bone loss.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: One 70 mg tablet per week

Route: Oral

Frequency: Once weekly

Osteoporosis. Missed dose: take it the following morning after realising it has been missed; do NOT take two tablets on the same day — continue with one tablet a week on the originally scheduled day. Administration (critical to absorption and to reducing oesophageal injury): take on an empty stomach immediately on rising in the morning with plain water only, at least 30 minutes before the first food, drink or other medication of the day; swallow whole with a whole glass of water (not less than 200 mL / 7 fl.oz); do not chew, suck or allow the tablet to dissolve in the mouth (risk of oropharyngeal ulceration); do not lie down for at least 30 minutes and until after the first meal of the day; do not take at bedtime or before arising for the day. Patients should be given a calcium and vitamin D supplement if the diet is inadequate. Duration: the optimal duration of bisphosphonate treatment for osteoporosis has not been established — the need for continued treatment should be re-evaluated periodically on an individual basis, particularly after 5 or more years of use. Elderly: no age-related difference in efficacy or safety in clinical trials — no dose adjustment necessary. Hepatic impairment: no dose adjustment necessary. Paediatric: alendronate sodium is NOT recommended for use in children under 18 years due to insufficient safety and efficacy data in conditions associated with paediatric osteoporosis. Alendronic acid has not been investigated in the treatment of glucocorticoid-induced osteoporosis. Source: eMC SPC for Alendronic Acid 70 mg Film-coated Tablets (§4.2). This SPC is for the 70 mg once-weekly product only — the daily 10 mg regimen appears only in the §4.8 trial data and is not part of this product's posology.

Dose adjustments

Renal

No dose adjustment is necessary in patients with a creatinine clearance greater than 35 mL/min. Alendronate is NOT recommended if creatinine clearance is less than 35 mL/min, as there is no experience in this group.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to the active substance or to any of the excipients
Oesophageal abnormalities and other factors that delay oesophageal emptying, such as stricture or achalasia
Inability to stand or sit upright for at least 30 minutes
Hypocalcaemia

Side effects

Gastrointestinal — common: abdominal pain, dyspepsia, constipation, diarrhoea, flatulence, abdominal distension, acid regurgitation, oesophageal ulcers and dysphagia; uncommon: nausea, vomiting, gastritis, oesophagitis, oesophageal erosions, melaena; rare: oesophageal stricture, oropharyngeal ulceration, upper gastrointestinal perforations, ulcers and bleeding
Musculoskeletal pain (bone, muscle or joints) — reported in about 2.9% on the 70 mg once-weekly tablet in the one-year study; muscle cramps
Nervous system — common: headache, dizziness; common: vertigo; uncommon: dysgeusia
Skin — common: alopecia, pruritus; rare: hypersensitivity reactions including urticaria and angioedema
Rare: symptomatic hypocalcaemia, often in association with predisposing conditions; uncommon: eye inflammation (uveitis, scleritis, episcleritis); very rare: osteonecrosis of the external auditory canal (bisphosphonate class effect)
Osteonecrosis of the jaw — reported in patients with osteoporosis receiving oral bisphosphonates (most reports are with intravenous bisphosphonates in cancer patients); consider risk factors including cancer, chemotherapy, radiotherapy, corticosteroids, angiogenesis inhibitors, smoking, dental disease, poor oral hygiene, periodontal disease and invasive dental procedures (SPC §4.4)

Interactions

Food, drinks (including mineral water) and other medicines are likely to reduce the absorption of alendronate — take at least 30 minutes before the first food, drink or other medication of the day (SPC §4.2, cross-referring to §4.5)
Calcium and vitamin D supplements — should be given if the diet is inadequate, but separated from the dose in line with the administration instructions above (SPC §4.2/§4.4)
NOTE: SPC §4.5 was not present in the fetched source — verify the full interactions section.

Clinical monograph

How it works

It binds avidly to bone mineral and is taken up by osteoclasts, where it inhibits the enzyme farnesyl pyrophosphate synthase, impairing osteoclast function and reducing bone resorption.

Prescribing in practice

To prevent serious oesophageal injury it must be taken on rising with a full glass of plain water, and the patient must remain upright and not lie down or eat until after the post-dose interval; it is contraindicated in oesophageal abnormalities or inability to stay upright.
Correct hypocalcaemia and vitamin D deficiency before starting, and ensure adequate calcium and vitamin D intake during treatment.
Counsel on the rare risks of osteonecrosis of the jaw and atypical femoral fracture, and assess dental health before and during therapy.

Monitoring

Monitor renal function and calcium status, reassess fracture risk periodically and review the need for a treatment break (drug holiday) after several years.

Counselling the patient

Take first thing in the morning with plain water only, then stay upright and avoid food and other medicines until after the recommended interval.
Report any difficulty or pain on swallowing, heartburn, or new thigh, hip or groin pain.
Maintain good oral hygiene and tell your dentist you take this medicine.

Evidence & guidelines

Fracture-prevention efficacy is supported by the FIT trials and reflected in NICE osteoporosis guidance.

Reference: NICE CG146 Osteoporosis; NOGG Guidelines 2021; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways