Oral Bisphosphonates

Introduction

Bisphosphonates (antiresorptive medications) are first-line therapy used for prevention and treatment of osteoporosis. Options include alendronate (oral), ibandronic acid (oral or IV), pamidronate (IV), risedronate (oral), zoledronic acid (IV).



Oral Dosage

  • Alendronate: 10 mg daily or 70 mg once a week
  • Ibandronic acid: 150 mg once monthly
  • Risedronate: 5 mg daily or 35 mg once a week or 150 mg once monthly



Method of Administration

Oral bisphosphonates bioavailability is less than 1% and is greatly decreased with concomitant food and beverages.
  • Each oral tablet should be taken in the morning with at least 6 oz (180 ml) of plain water (not coffee, juice, mineral water, or milk) at least 30 minutes (60 minutes for oral ibandronate) before consuming any food, supplements, or medications. An exception is delayed-release risedronate, which is administered immediately after breakfast with at least 4 oz (120 ml) of plain water.



Missed Dose Management

If patient misses a weekly dose, it can be taken the next day. If more than 1 day has elapsed, that dose is skipped until the next scheduled ingestion.

If a patient misses a monthly dose, it can be taken up to 7 days before the next scheduled dose.



Adverse Effects

Upper gastrointestinal (GI) side effects (reflux, oesophagitis, oesophageal ulcers) are a commonly cited reason for oral bisphosphonate intolerance.

  • The patient should remain upright (sitting or standing) for at least 30 minutes after alendronate and risedronate and 1 hour after ibandronate administration to prevent oesophageal irritation and ulceration.

Both oral and IV bisphosphonates can cause transient hypocalcaemia, but it occurs more frequently after IV than oral administration.

  • Ensure vitamin D status and calcium intake are adequate; if necessary, prescribe supplements (to be taken at a different time of day to oral bisphosphonates).

Rare adverse effects include osteonecrosis of the jaw (ONJ), severe musculoskeletal pain, ocular side effects and subtrochanteric femoral (atypical) fractures.

  • There are rare complications with some dental procedures in people taking bisphosphonates; tell your doctor if you require any dental work and tell your dentist that you are taking this medicine (or have taken it in the past).
  • ONJ occurs more commonly in patients with cancer, receiving higher-dose intravenous bisphosphonate therapy and other risk factors including glucocorticoid therapy and diabetes mellitus.
  • Although rare, some patients have experienced severe musculoskeletal pain (bone, joint, and/or muscle pain) within days, months, or years after starting a bisphosphonate, and symptoms do not always resolve completely with discontinuation of therapy.
  • Ocular side effects including pain, blurred vision, conjunctivitis, uveitis, and scleritis have been reported with most bisphosphonates
  • Drug holidays are controversial; bone density may decrease 5 years after discontinuation of bisphosphonate therapy.



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