US guidelines for the treatment of osteoporosis have been published. The diagnosis of osteoporosis has traditionally been established by the occurrence of fragility fractures or by bone densitometry, which is generally reported in terms of standard deviations (SD) from mean values in young adults (T-score). The World Health Organization (WHO) has defined normal bone mineral density (BMD) for women as a value within one SD of the young adult mean. Values 2.5 SD or more below the mean (T-score -2.5 or below) at the spine, femoral neck, or total hip are defined as osteoporosis. The WHO has developed a computerized model (FRAX) that predicts the 10-year probability of a hip fracture or other major osteoporotic fracture based on clinical risk factors and BMD at the femoral neck.

The In-Brief article on delayed-release risedronate in issue 1360 (Med Lett Drugs Ther 2011; 53:24) included a statement that alendronate is currently the only bisphosphonate available generically. That would have been accurate if we had added "that is FDA-approved for treatment of osteoporosis." Etidronate (Didronel, and others), which was the first bisphosphonate used to treat osteoporosis (Medical Letter 1990; 32:111) but was never approved for such use by the FDA, is also available generically. It is approved for treatment of Paget's disease and for prevention and treatment of heterotropic ossification following hip replacement and in spinal-cord injured patients.

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Many drugs are now marketed for treatment of postmenopausal osteoporosis, but questions remain about their use.

A 10-year study of daily oral alendronate (Fosamax) and a 7-year study of daily oral risedronate (Actonel) indicate that both drugs maintained increases in bone mineral density (BMD) and decreases in markers of bone remodeling throughout the study period. Both drugs are now more commonly taken once weekly. Available data are insufficient to compare fracture rates with alendronate and risedronate, and fracture rates are considered the most important endpoint in osteoporosis studies. Recent reports of severe pain and jaw osteonecrosis with these drugs are disturbing.

Many drugs are now marketed for treatment of post-menopausal osteoporosis (PD Delmas, Lancet 2002; 359:2018). Prevention of this disorder has been complicated by the news that hormone replacement therapy (HRT), which many women have been taking to prevent osteoporosis, increases the incidence of coronary heart disease and that of breast cancer, stroke and pulmonary embolism as well (Medical Letter 2002; 44:78).

Older patients are especially susceptible to drug-induced cognitive impairment. They are more likely to be taking multiple drugs, to have higher blood levels of those drugs because of renal or hepatic dysfunction, and to have pre-existing cognitive problems that make it difficult to detect the role of drugs causing new symptoms or making old ones worse.

Risedronate (Actonel - Procter & Gamble), a pyridinyl bisphosphonate, has been approved by the FDA for oral treatment of Paget's disease of bone. Characterized by excessive bone resorption, bony deformity, disorganized bone remodeling and structural weakness, Paget's disease occurs in up to 3% of people older than 55 in Europe and North America (PD Delmas and PJ Meunier, N Engl J Med, 336:558, 1997).

Tiludronate (Skelid - Sanofi), a chloro-4-phenylthiomethylene bisphosphonate, has been approved by the US Food and Drug Administration (FDA) for treatment of Paget's disease of bone. Characterized by excessive bone resorption and disorganized bone remodeling, Paget's disease occurs in up to 3% of people more than 55 years old in Europe and North America (PD Delmas and PJ Meunier, N Engl J Med, 336:558, Feb 20, 1997).

Two new drugs alendronate (Fosamax - Merck) and salmon calcitonin nasalspray (Miacalcin - Sandoz) are now available in the USA for treatment of postmenopausalosteoporosis. A third drug for treatment of osteoporosis, a slow-release fluoridepreparation (Slow Fluoride -Mission Pharmacal), has been recommended for approvalby an advisory committee of the US Food and Drug Administration (FDA). Various formulationsof fluoride have been available in Europe for this indication for many years.

The bone mass of an average person reaches a maximum at the age of 25 to 30, stays the same for about 15 years, and then progressively declines at a rate of 0.2% to 0.5% per year. At menopause, women go through a period of increased bone resorption (2% per year) for about 10 years and then resume a gradual rate of bone loss. Current strategies for prevention and treatment of Postmenopausal Osteoporosis include increasing calcium intake to maximize peak bone mass, using antiresorptive drugs to decrease postmenopausal resorption, and using other drugs to stimulate bone systhesis (BL Riggs and LJ Melton, III, N Engl J Med, 327:620, Aug 27, 1992).

Disodium pamidronate (Aredia - Ciba-Geigy), an aminohydroxypropilidene bisphosphonate, has been approved by the US Food and Drug Administration for intravenous (IV) treatment of hypercalcemia associated with malignancy, with or without bone metastases. The drug is also being investigated for use in Paget's disease of bone, hyperparathyroidism, and postmenopausal osteoporosis. An oral formulation of pamidronate has been used in Europe, but is not available in the USA.

Gallium nitrate (Ganite - Fujisawa, USA), originally an anticancer drug, was recently marketed for treatment of cancer-associated hypercalcemia that has not responded to hydration. Other drugs used for treatment of hypercalcemia include furosemide (Lasix, and others), the bisphosphonate etidronate (Didronel IV), calcitonin (Calcimar), and plicamycin (Mithracin, formerly mithramycin) (RAB Schaiff et al, Clin Pharm, 8:108, 1989). Newer bisphosphonates are available in Europe.

Etidronate (e ti droe' nate) disodium (Didronel - Norwich Eaton), an oral bisphosphonate available for many years for treatment of Paget's disease (Medical Letter, 20:78, 1978), recently has also been used for treatment of postmenopausal osteoporosis.