There is a range of effective and well tolerated medicines now available for the treatment of osteoporosis. Treatment is recommended both for people who are at risk of fracture because they have low bone density and risk factors for osteoporosis, and for those who have already experienced a minimal trauma fracture ( a fracture sustained after a fall from a standing height or less). It is essential that patients taking osteoporosis medications also maintain adequate levels of calcium and vitamin D and exercise regularly, in order to optimise the effectiveness of the medication. Calcium and vitamin D supplementation may be required where there is a deficiency, particularly in elderly people. Some bisphosphonate products include calcium and vitamin D supplements.
Who should be treated?
People with osteoporosis
• Any man or woman who has suffered a fracture after minimal trauma, even if the T-score is above -2.5. Treatment should begin immediately, and a DXA scan performed to establish the extent of bone loss and a baseline for treatment. If the T-score proves to be normal (> -1.0), reconsider treatment, taking into account the patient’s absolute fracture risk.
• No fracture, but a T-score of ≤ -2.5. Treat if risk factors for osteoporosis are present. Treatment may not be necessary in the following circumstances:
o The patient has modifiable risk factors only
o Women under 55 years of age
o Men under 60 years of age
These categories are generally associated with low absolute risk of fracture, but treatment decisions should be made on the basis of individual risk
• Osteoporosis due to secondary causes. In addition to pharmacological treatment for osteoporosis, any suspected underlying causes of bone loss should be investigated and appropriately managed.
People with osteopenia
• Any man or woman with osteopenia (T-score between -1.0 and -2.5) and a minimal trauma fracture should be treated.
• There are limited data on the value of treating people who have osteopenia but have not had a minimal trauma fracture. These patients should be counselled about the need for adequate calcium, vitamin D and exercise, and advised about healthy lifestyle choices. Educate patients about the signs of vertebral fracture, and repeat DXA scan in two to five years, depending on the severity of osteopenia and the patient’s individual risk factors.
People with special circumstances
• All people over the age of 50 on corticosteroid therapy (oral or inhaled) of 7.5 mg per day for at least 3 months and with a T-Score of -1.5 or less should receive drug therapy to prevent osteoporosis. This should be continued for the duration of the corticosteroid therapy.
• Women treated with aromatase inhibitors for breast cancer and men on anti-androgen therapy may benefit from preventive treatment with osteoporosis drugs, depending on the patient’s absolute risk of fracture.
PBS availability of osteoporosis medicines
The PBS subsidises osteoporosis medications on the basis of age, T-score and whether or not the patient has already sustained a minimal trauma fracture. For the prevention of first fractures in people with low bone density, subsidy is currently restricted to people over 70 years of age, with a T-score of ≤ -2.5 or ≤ -3.0, depending on the medication prescribed.
PBS subsidy of osteoporosis medication is available to all people who have suffered a minimal trauma fracture to reduce the risk of further fractures. Subsidy applies regardless of age or T-score.
Types of medicines for osteoporosis
Bisphosphonates inhibit bone resorption, preventing further bone loss and improving bone density over time. They are available as daily, weekly or monthly tablets (alendronate, risedronate), or as an annual infusion (zoledronic acid). Bisphosphonates are indicated (and are available on the PBS) for the prevention of first fracture in men and women with low bone density, to reduce the risk of further fractures in patients who have already sustained a minimal trauma fracture, and to prevent fractures in those undergoing long-term corticosteroid therapy. These drugs are generally well tolerated, with gastro-intestinal discomfort being the most commonly reported side-effect with tablets. This can be minimised by ensuring that the patient remains upright for the recommended period after taking the tablets.
Densoumab (monoclonal antibody against RANK-ligand)
Denosumab inhibits resorptive activity by a different mechanism to that of the bisphosphonates. This drug is given as a 6-monthly subcutaneous injection, and may be an alternative for those who find bisphosphonates difficult to tolerate or who prefer twice-yearly administration to daily or weekly dosing. Denosumab is indicated, and is available on the PBS, for the prevention of first fracture in men and women with low bone density, and to reduce the risk of further fractures in men and women who have already sustained a minimal trauma fracture.
Strontium ranelate both inhibits resorption and increases bone formation, although its main mode of action is uncertain. It taken as a daily powder, dissolved in water. Strontium ranelate is PBS-subsidised only for men and women who have already sustained a minimal trauma fracture, in order to prevent further fractures. There is a small increased risk of myocardial infarction in patients taking this drug, and patients should be evaluated for cardiovascular risk prior to commencing this drug, as well as during treatment.
Raloxifene (selective oestrogen- receptor modulator)
Raloxifene has oestrogen-like effects on bone but oestrogen-antagonist effects on breast and endometrium. It is taken as a daily tablet. Raloxifene is indicated and PBS-subsidised for post-menopausal women who have already sustained a minimal trauma fracture, and is recommended where the patient is at higher risk of vertebral fracture than fractures at other sites.
Hormone replacement therapy
HRT slows the rate of bone loss through restoration of oestrogen levels in post-menopausal women. HRT is now considered to be a safe option for osteoporosis treatment for most younger women (those under 60) who are at risk of minimal trauma fracture, and who also require treatment for menopausal symptoms. Women over 60 should be offered alternative osteoporosis medications, as the risk of cardiovascular events after this age is increased.
Second-line treatments for osteoporosis
Teriparatide (recombinant parathyroid hormone)
Teriparatide stimulates the production of new bone, and is indicated only in cases of severe osteoporosis, where first line treatments have failed. The drug is self-administered as a subcutaneous daily injection using a pre-filled multi-dose delivery pen. Treatment must be initiated by a specialist, but can be continued by a GP. The course of treatment must not exceed 18 months. The PBS subsidises teriparatide treatment for men and women with a T-score ≤-3.0 and two or more minimal trauma fractures, one of which must have occurred after 12 months on an anti-resorptive therapy. After the course of teriparatide has finished, treatment with an anti-resportive drug must begin in order to maintain the new bone that has been built with the teriparatide.