Effective oral treatment of severe Paget's disease of bone with APD (3-amino-1-hydroxypropylidene-1,1-bisphosphonate); a comparison with combined calcitonin + EHDP (1-hydroxyethylidene-1,1-bisphosphonate).

Ten patients with severe Paget's disease of bone and serum alkaline phosphatase (sAP) greater than 900 IU/l were treated for six months with the oral diphosphonate APD, (3-amino-1-hydroxypropylidene-1, 1-bisphosphonate). By the end of the treatment period there was a reduction in the log mean urine hydroxyproline (uHP) and the log mean sAP of 92% and 87% respectively. In four patients both sAP and uHP fell to within the normal range and remained normal for at least six months after therapy was stopped. Bone scintigraphy showed a fall in 99mTc-MDP uptake in sites of active Paget's disease in all patients and histomorphometry showed no increase in osteoid. Repair of radiological osteolytic lesions was observed in 6/6 patients and progression of tibial osteolytic wedges was arrested in 5/5 patients and reversed in four. This improvement persisted six months after completion of therapy but further wedge progression occurred in one patient whose urine HP remained elevated. There were no serious effects though five patients complained of nausea. The clinical and biochemical responses to APD were equivalent to those observed in the same patients during a previous six month course of combined therapy with human calcitonin (CT) + EHDP except that there was additional biochemical and radiological evidence of bone healing. This study confirms PAD as an effective treatment of severe Paget's disease of bone.