Fosamax, Fosamax D (with 2800 IU Vitamin D3)
Classifications: bisphosphonate; regulator, bone metabolism;
Therapeutic: bone metabolism regulator

Prototype: Etidronate
Pregnancy Category: C


5 mg, 10 mg, 35 mg, 40 mg, 70 mg tablets; 70 mg/75 mL oral solution


A bisphosphonate that inhibits osteoclast-mediated bone resorption. Antiresorption mechanism is thought to be localized to resorption sites of active bone turnover and to have minimal to no interference with bone mineralization.

Therapeutic Effect

Alendronate decreases bone resorption, thus minimizing loss of bone density.


Prevention and treatment of osteoporosis in postmenopausal women, Paget's disease. Treatment of glucocorticoid-induced osteoporosis.


Hypersensitivity to alendronate or other bisphosphonates; achalasia, esophageal stricture, severe renal impairment (Clcr <35 mL/min); hypocalcemia; abnormalities; pregnancy (category C); lactation.

Cautious Use

Renal impairment, CHF, hyperphosphatemia, liver disease, fever or infection, active upper GI problems.

Route & Dosage

Treatment of Osteoporosis
Adult: PO 10 mg once/d (max: 40 mg/d) or 70 mg q wk

Prevention of Osteoporosis, Treatment of Steroid-induced Osteoporosis
Adult: PO 5 mg q.d. or 35 mg q wk

Treatment of Paget's Disease
Adult: PO 40 mg once/d for 6 mo

Renal Impairment
Clcr <35 mL/min: use not recommended


  • Correct hypocalcemia before administering alendronate.
  • Administer in the morning at least 30 min before the first food, beverage, or medication. Do not administer within 2 h of calcium-containing foods, beverages, or medications. At least 30 min should elapse after alendronate dose before taking any other drugs.
  • Oral Solution: Use oral syringe for accurate dosage. Give with at least 60 cc (2 oz) of plain water.
  • Tablet: Give with 8 oz of plain water.
  • Keep patient sitting up or ambulating for 30 min after taking drug.
  • Store according to manufacturer's directions.

Adverse Effects (≥1%)

Endocrine: Hypocalcemia, hypophosphatemia. GI: Esophageal irritation and ulceration, nausea, vomiting, abdominal pain, dyspepsia, diarrhea, constipation, flatulence. Other: Arthralgias, myalgias, headache, rash.


Drug: Ranitidine increases alendronate availability. Food: Calcium and food (especially dairy products) reduce alendronate absorption.


Absorption: 0.5–1% from GI tract (absorption significantly decreased by calcium and food). Onset: 3–6 wk. Duration: 12 wk after discontinuation. Distribution: Rapid skeletal uptake. Metabolism: Not metabolized. Elimination: Up to 50% excreted unchanged in urine. Half-Life: Up to 10 h.

Nursing Implications

Assessment & Drug Effects

  • Lab tests: Monitor albumin-adjusted serum calcium, serum phosphate, serum alkaline phosphatase, fasting and 24 h urinary calcium, and serum electrolytes. Periodically monitor renal and liver functions.
  • Diagnostic test: Bone density scan every 12–18 mo.
  • Discontinue drug if the Clcr <35 mL/min.

Patient & Family Education

  • Review directions for taking drug correctly (see ADMINISTRATION).
  • Report fever, especially when accompanied by arthralgia and myalgia.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

© 2006-2022 Last Updated On: 11/20/2022 (0)
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