Intravenous pamidronate compared with oral alendronate for the treatment of postmenopausal osteoporosis

There are several options for the treatment of osteoporosis in postmenopausal women. One of the options is treatment with bisphosphonates, which are very potent inhibitors of osteoclast-mediated bone resorption in vitro and in vivo. The most potent bisphosphonates have a nitrogen side chain and can be given orally or intravenously (i.v.). In the present study we evaluated retrospectively the effect of intravenously administered pamidronate (60 mg monthly) in comparison with oral alendronate with regard to bone mineral density (BMD) and vertebral fractures. A total of 117 consecutive women aged 46 to 78 years were seen in the outpatient clinic because of postmenopausal osteoporosis. Three-year follow-up data were available for a total of 45 patients treated with pamidronate i.v. and 40 patients on alendronate for at least three years. In the pamidronate group mean T score of lumbar spine BMD increased from -3.49 +/- 0.72 to -2.81 +/- 0.74 SDs after three years of treatment (p < 0.001). In the 40 patients treated with alendronate we observed an increase in the T score from -2.95 +/- 0.67 to -2.33 +/- 0.74 SDs (p < 0.001) during the same observation period. X-rays of the lumbar and thoracic spine were analysed from 25 patients in each group who had been treated for at least three years. At baseline nine patients (36%) in the pamidronate group had one or more vertebral fractures compared with seven patients (28%) in the alendronate group. After three years of treatment no new fractures were observed, while only three women in the pamidronate group and two in the alendronate group showed a deterioration of one or more pre-existing vertebral fractures (p = ns between groups). This retrospective analysis demonstrates that monthly intravenous administration of pamidronate is at least as good as alendronate taken orally in the treatment of women with postmenopausal osteoporosis, with regard to improvement of bone mineral density of the lumbar spine. We conclude that it is a good alternative for the more widely used oral bisphosphonates as it is effective, well-tolerated and easy to administer.