Health Canada is investigating whether long-term use of a drug used to treat osteoporosis and two other calcium-related conditions increases the risk of cancer.

Calcitonin is prescribed as a nasal spray to treat osteoporosis — the thinning of bones — in postmenopausal women. It is also available as a solution for injection to treat Paget's disease and severe hypercalcemia, or high blood calcium.

Osteoporosis leads to brittle, easily fractured bones. (iStock)

Paget's disease is a chronic condition that causes abnormal bone growth, while severe hypercalcemia is a medical emergency that can lead to kidney failure, heart problems and coma.

The European Medicines Agency (EMA) recently recommended that the use of calcitonin be restricted because evidence suggests the drug may increase the risk of cancer.

The agency said calcitonin nasal sprays should no longer be prescribed for the treatment of osteoporosis. Injectable calcitonin should be used for Paget's disease only when other treatments have failed or are inappropriate — and treatment should normally be limited to three months.

Injectable calcitonin should be used only for hypercalcemia caused by cancer, the EMA advised.

Health Canada has made no recommendations about calcitonin use. But the federal department said Tuesday it is reviewing all available information on the drug and any new safety information will be communicated to prescribers and patients as soon as that assessment is completed.

No reports of cancer associated with calcitonin have been reported to Health Canada since the drug was first approved in 1983.

Patients taking a calcitonin medicine should speak to their health-care provider before considering stopping treatment, said Health Canada, noting that other medications are available for osteoporosis, Paget's disease and hypercalcemia.

Calcitonin products currently available in Canada:

• Miacalcin nasal spray, 200 IU, Novartis, DIN 02240775.
• Apo-Calcitonin nasal spray, Apotex., DIN 02247585.
• Sandoz-Calcitonin nasal spray, Sandoz, DIN 02261766.
• Apo-Calcitonin injectable, Apotex, DIN 02246058.
• Calcimar injectable, 200 unit/ml, Sanofi-Aventis, DIN 01926691.
• Caltine injectable, 100 unit/ml, Ferring Inc., DIN 02007134.