Osteoporosis New Zealand

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Medications for the Treatment of Osteoporosis: Bisphosphonates

Bisphosphonates are first line treatment. Two oral tablet formulations are available in New Zealand, alendronate and etidronate. Alendronate is the more potent of these is fully subsidised and widely available with few access restrictions. Current availability criteria are:

• T score ≤ -3.0.
• T score < -2.5 plus fragility fracture.
• History of two significant osteoporotic fractures demonstrated radiologically.
• History of one significant osteoporotic fracture with x-ray confirmation in frail elderly unable to access DEXA scan.
• Glucocorticoids >5 mgs daily either on, or intended to be on, for > 3 months and either a T score of ≤ -1.5 or one significant osteoporotic fracture demonstrated radiologically.

• Bisphosphonates are effective strategies for preventing fracture and are generally well tolerated, although some people experience upper gastrointestinal side effects with the amino bisphosphonates (e.g. alendronate).
• In people with osteoporosis, bisphosphonates combined with adequate calcium and vitamin D, are clearly more beneficial than calcium and vitamin D alone.
• Alendronate has been shown to decrease the risk for fracture at all sites by up to 56% within a few months of commencing treatment.
• Etidronate has demonstrated a lesser level of efficacy in preventing vertebral fractures, but has no proven effect in reducing hip fracture.
• Intermittent parenteral administration of intravenous bisphosphonates is a further option with this class of medications. From 1 September 2010, Zoledronate will be registered for the treatment of osteoporosis in New Zealand. 5 mg IV 1-2 yearly has now been shown to be at least as effective as alendronate in fracture risk reduction in both hip and spine. IV therapy might be considered for the severely osteoporotic intolerant of oral alendronate.
• The ongoing need for bisphosphonate therapy should be reviewed at intervals and in all patients at five years. Ongoing therapy decisions might be based on the severity of osteoporosis, response to therapy, presence of side effects and the potential for adverse effects associated with long-term use, e.g. the low risk of severe suppression of bone turnover.