Alendronic Acid (Alendronate)

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.