Alendronic Acid

1. Introduction

Alendronic acid, commonly marketed under brand names such as Fosamax and Binosto, is a bisphosphonate used primarily for the prevention and treatment of osteoporosis. It works by inhibiting osteoclast-mediated bone resorption, thereby increasing bone mineral density.

2. Indications

  • Approved Indications:
    • Treatment and prevention of osteoporosis in postmenopausal women.
    • Treatment of osteoporosis in men.
    • Glucocorticoid-induced osteoporosis in patients receiving long-term steroid therapy.
    • Treatment of Paget’s disease of bone.
  • Off-Label Uses:
    • Reduction of fracture risk in high-risk patients.

3. Dosage

  • Osteoporosis (Postmenopausal Women and Men):
    • 10 mg once daily OR 70 mg once weekly.
  • Glucocorticoid-Induced Osteoporosis:
    • 5 mg once daily OR 10 mg once daily (for postmenopausal women not on hormone replacement therapy).
  • Paget’s Disease:
    • 40 mg once daily for 6 months.

4. Administration

  • Take orally with a full glass of water (at least 200 mL).
  • Administer at least 30 minutes before the first food, drink, or medication of the day.
  • Remain upright (sitting or standing) for at least 30 minutes after administration.
  • Avoid lying down immediately to reduce the risk of oesophageal irritation.

5. Forms Available

  • Tablets: 5 mg, 10 mg, 35 mg, 40 mg, 70 mg.
  • Effervescent tablets (Binosto): 70 mg.

6. Side Effects

6.1. Common Side Effects

  • Abdominal pain.
  • Dyspepsia.
  • Musculoskeletal pain (bone, joint, or muscle).
  • Nausea.

6.2. Less Common Side Effects

  • Oesophageal ulcer or irritation.
  • Constipation or diarrhoea.
  • Headache.

6.3. Rare but Serious Side Effects

  • Osteonecrosis of the jaw (ONJ).
  • Atypical femoral fractures.
  • Severe oesophageal reactions (stricture, perforation).
  • Hypocalcaemia.

7. Warnings

  • Contraindicated in patients with oesophageal abnormalities that delay oesophageal emptying.
  • Avoid use in patients who cannot remain upright for 30 minutes.
  • Risk of severe musculoskeletal pain and osteonecrosis of the jaw.

8. Precautions

  • Use with caution in patients with active upper gastrointestinal disorders.
  • Correct hypocalcaemia and vitamin D deficiency before starting therapy.
  • Monitor dental health in patients at risk for osteonecrosis.

9. Interactions

  • Calcium supplements, antacids, or other multivalent cations may interfere with absorption.
  • Avoid simultaneous administration with NSAIDs to reduce gastrointestinal irritation.
  • Alcohol use may exacerbate gastrointestinal side effects.

10. Monitoring Parameters

  • Bone mineral density (BMD) every 1–2 years.
  • Serum calcium and vitamin D levels.
  • Renal function (baseline and periodic).

11. Use in Children

  • Not recommended; safety and efficacy have not been established in paediatric populations.

12. Use in Pregnancy

  • Category C: Risk cannot be ruled out.
  • Use only if the potential benefit justifies the risk to the foetus.
  • Animal studies show adverse skeletal effects on the developing foetus.

13. Use in Elderly

  • No specific dose adjustment needed.
  • Increased susceptibility to gastrointestinal side effects and renal impairment requires careful monitoring.

14. Use in Kidney Disease

  • Avoid use in patients with creatinine clearance <35 mL/min.
  • No dosage adjustment necessary for mild-to-moderate renal impairment.

15. Use in Liver Disease

  • No dosage adjustment required; alendronic acid is not metabolised by the liver.

16. Patient Counselling Points

  • Emphasise taking the tablet with water on an empty stomach.
  • Highlight the need to remain upright for at least 30 minutes after ingestion.
  • Inform about the importance of regular dental check-ups.
  • Advise reporting any signs of jaw pain, severe bone pain, or difficulty swallowing immediately.

17. Table of Brand Names, Manufacturers, and Prices

Brand NameManufacturerPrice (USD)
FosamaxMerck & Co.$30 (70 mg x 4)
BinostoMission Pharmacal$45 (70 mg x 4)
Generic OptionsVarious$15 (70 mg x 4)

18. FAQs (15 Questions)

  1. What is alendronic acid used for?
    Alendronic acid is used for treating osteoporosis, Paget’s disease, and preventing fractures in at-risk patients.
  2. How does alendronic acid work?
    It inhibits bone resorption by osteoclasts, increasing bone density.
  3. Can I take alendronic acid with food?
    No, it should be taken on an empty stomach with water only.
  4. What are the common side effects of alendronic acid?
    Abdominal pain, nausea, and musculoskeletal pain are common.
  5. Are there any serious side effects?
    Yes, osteonecrosis of the jaw and atypical femoral fractures are rare but serious.
  6. Can pregnant women take alendronic acid?
    It is not recommended due to potential risks to the foetus.
  7. Can children use alendronic acid?
    No, its use is not established in children.
  8. How should alendronic acid be stored?
    Store at room temperature, away from moisture and heat.
  9. What happens if I miss a dose?
    Take the dose the next morning; do not take two tablets in one day.
  10. Can I drink alcohol while taking alendronic acid?
    It is best to avoid alcohol to minimise gastrointestinal irritation.
  11. What are the signs of an overdose?
    Symptoms include hypocalcaemia, hypophosphataemia, and upper GI side effects.
  12. Is alendronic acid safe for elderly patients?
    Yes, but with careful monitoring for side effects.
  13. Can alendronic acid interact with other medications?
    Yes, avoid taking it with calcium, antacids, or NSAIDs at the same time.
  14. How long does it take for alendronic acid to work?
    Significant effects on bone density may take 6–12 months.
  15. Do I need regular tests while taking alendronic acid?
    Yes, regular bone density, calcium, and kidney function tests are advised.