Maintained improvement in calcium balance and bone mineral content in patients with osteoporosis treated with the bisphosphonate APD.

The effects of the (3-amino-1-hydroxypropylidene)-1,1-bisphosphonate (APD) in osteoporosis were investigated in a series of open studies. Seven patients received a high dose of 600 mg/day of APD orally and showed an increase in calcium balance of 5.5 mmol/day (P less than 0.01) within a period of 10 days. In a group of 14 patients with osteoporosis, receiving a low dose of 150 mg/day of APD continuously, the mean calcium balance rose from -0.72 +/- 0.59 mmol/day before treatment to 1.33 +/- 0.87 mmol/day (P less than 0.005) after 1 year. In 24 patients treated with APD 150 mg/day for a mean period of 3.7 years (range 1.4-6.2) repeated dual photon absorptiometry measurements of the lumbar spine showed a mean rate of increase in bone mineral content of 3.1 +/- 1.0% per year (P less than 0.005). This yearly gain in bone mineral content appeared continuous for several years of treatment. In a comparable group of 19 patients with osteoporosis who also received conventional care and treatment but no APD, no significant changes in bone mineral content were found. Addition of a low dose of APD to conventional treatment of osteoporosis does not only prevent bone loss but induces a continuous gain in bone mass. These results justify long-term prospective studies with uninterrupted low dose APD treatment in osteoporosis.