ALENDRONATE - A REVIEW OF ITS PHARMACOLOGICAL PROPERTIES AND THERAPEUTIC EFFICACY IN POSTMENOPAUSAL OSTEOPOROSIS

Alendronate is an aminobisphosphonate which appears to attenuate, rath er than completely inhibiting bone turnover by suppressing the activit y of osteoclasts. Clinical trials have established that 10 mg/day oral ly administered alendronate is the optimum dosage. Despite its poor bi oavailability after oral administration, alendronate is highly effecti ve at preventing bone loss associated with the absence of endogenous e strogen. A sustained increase in bone mass was observed during alendro nate therapy without accelerated loss after withdrawal of the drug. In creased bone mass was associated with a reduction in the risk and rate of occurrence of vertebral fractures. A recent study demonstrated a 4 7% reduction in the risk of developing new radiographic vertebral frac tures over 3 years in women with low bone mass and pre-existing verteb ral fractures. There have been few direct comparisons in clinical tria ls. However; when compared with calcium or low dosages of salmon calci tonin (salcatonin) therapy in women with postmenopausal osteoporosis, alendronate induced a sustained increase in bone mass during therapy t hat was not seen with the comparator: In clinical trials alendronate w as generally well tolerated when taken as recommended. Adverse events tended to be transient and usually associated with the upper gastroint estinal tract; the most common events included abdominal pain, nausea, dyspepsia, constipation and diarrhoea, which are also common with oth er bisphosphonates. Of potential concern are the small number of repor ts of patients developing oesophageal ulceration; however this adverse event was attributed to noncompliance with rite manufacturer's recomm endations for administration of the drug. In addition, alendronate has nor been associated with osteomalacia. Studies are still required to establish the long term efficacy of alendronate, particularly with reg ard to other available therapies. Although estrogen replacement therap y is generally considered the treatment of choice for the management o f postmenopausal osteoporosis, many women are unable or unwilling to r eceive estrogens on a long term basis. Thus, alendronate, with its dem onstrated beneficial effects and its good, tolerability profile (when taken as recommended), is a promising alternative treatment option for the management of postmenopausal osteoporosis.