ALENDRONIC ACID - Watsons Health


Alendronic acid is drug that inhibits bone resorption through its binding to a substance in the bone called hydroxyapatite and also inhibiting the function of bone resorbing cells called osteoclasts. This substance is poorly absorbed in the gastrointestinal tract and cannot be absorbed well when taken with food.

Alendronic acid is used in the treatment of osteoporosis that occurs during menopause in women and it is also used to increase bone mass in men with osteoporosis. It is also used to treat bone loss due to steroids as well as Paget’s disease of the bone.

Alendronic acid should not be given to people with esophageal problems and those who cannot stand up or sit upright for at least 30 minutes. This should not be given to people with low blood calcium levels, as well as in those who are at risk for aspiration and who have difficulties in swallowing.

Alendronic acid may have the following side effects such as the following:

  • Abdominal pain
  • Dyspepsia
  • Diarrhoea
  • Constipation
  • Esophagitis
  • Esophageal erosions, ulceration, or stricture
  • Peptic ulceration
  • Osteonecrosis of the jaw
  • Bone/joint/muscle pain
  • Femoral fracture
  • Hypocalcaemia
  • Nausea
  • Stevens Johnson syndrome (rare)
  • Toxic epidermal necrolysis (rare)


Take precautions in people who have the following medical conditions:

  • Patient with active gastrointestinal problems
  • History of major gastrointestinal disease such as peptic ulcer, or gastrointestinal bleeding)
  • Surgery of the upper gastrointestinal tract other than pyloroplasty
  • Renal impairment
  • Pregnancy and lactation



Alendronic acid may interact with the following medicines:

  • Antacids
  • Calcium supplements
  • Oral medications containing multivalent cations
  • Aspirin
  • NSAIDs

Symptoms of overdose include the following:

  • Hypocalcaemia
  • Hypophosphataemia
  • Upper GI adverse events (e.g. upset stomach, heartburn, oesophagitis, gastritis, ulcer)

If this happens, keep the patient upright and bring patient to the hospital immediately. The doctor may give milk or antacids to bind alendronate.


Available Brands:

  • Fosavance
  • Fosamax

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