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  Alendronate (Fosamax)
 
Author: Donna Karasic, PharmD Last modified: March 31, 2002
 

  INDICATIONS

  • Osteoporosis in men
  • Osteoporosis (prevention and treatment) in postmenopausal women
  • Glucocorticoid-induced osteoporosis
  • Paget's Disease

  DOSAGE

  • Osteoporosis in men: 10mg once daily or 70mg once weekly.
  • Osteoporosis in women: prevention-35mg once weekly or 5mg once daily.
  • Osteoporosis in women: treatment -70mg once weekly or 10mg once daily.
  • Glucocorticoid-induced osteoporosis: 5mg once daily. For Postmenopausal females not on estrogen therapy- 10mg once daily.
  • Paget's Disease: 40mg once daily for 6 months.

  PHARMACOKINETICS

  • Elimination half-life is estimated to exceed 10 years
  • Onset of action is 3 weeks.
  • Oral absorption in men is 0.59% and 0.7% in women.
  • Alendronate is not metabolized.
  • Presence of food and calcium reduces oral absorption significantly.

  ADVERSE EFFECTS

  • Abdominal pain (6.6%)
  • Dyspepsia (3.6%)
  • Constipation (3.1%)
  • Diarrhea (3.1%)
  • Flatulence (2.6%)
  • Esophageal Ulcer (1.5%)
  • Nausea (3.6%)
  • Musculoskeletal pain (6%)

  CONTRAINDICATIONS

  • Hypersensitivity to alendronate or any component of the product
  • Hypocalcemia
  • Esophageal abnormalities which delay esophageal emptying
  • Inability to stand or sit upright for 30 minutes after the dose
  • Creatinine clearance less than 35 ml/min

  DRUG INTERACTIONS

  • Calcium supplements
  • Antacids containing calcium
  • Aspirin

  FORMS

  • 5mg and 10mg tablets (for daily dosing)
  • 35mg, 40mg and 70mg tablets (for weekly dosing)

  MECHANISM OF ACTION

  • Alendronate is an aminobisphosphonate; it inhibits osteoclast-mediated bone resorption
  • It is most similar chemically to pamidronate
  • Alendronate contains a side-chain amino group, which imparts greater potency and specificity than earlier biphosphonates
  • Alendronate localizes preferentially to resorption sites of active bone turnover; bone resorption has been inhibited at doses that have minimal or no effect on bone mineralization
 
IMPORTANT POINTS/RECOMMENDATIONS
  • Dose should be taken with 6-8 ounces of plain water ONLY (no coffee or OJ) first thing in the morning 30 minutes or more before the first food, beverage or medication of the day.
  • Patient must sit or stand upright (do not lie down) for 30 minutes or more after dose is taken to facilitate delivery to the stomach and reduce esophageal irritation.
  • Do not take at bedtime or before arising for the day.
  • Patients should receive supplemental vitamin D and calcium for optimal treatment of osteoporosis.
 
REFERENCES
  1. Hutchison TA & Shahan DR (Eds): ;  Alendronate ;  MICROMEDEX┬« Healthcare Series: MICROMEDEX, Greenwood Village, Colorado (Edition expires 3-2002)

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