Abstract
Patients with Paget's disease of bone were treated with oral disodium dihydrogen ethylidene-1-hydroxy-1,1-bisphosphonate (EHBP), a drug that is known to stimulate renal tubular reabsorption of orthophosphate. After 2 weeks of treatment, plasma P sub(i), rose from 1.02 to 1.67 mmol/l. No increase in P sub(i) was observed with the related drug, dichloromethylene bisphosphonate, which also reduces bone turnover in Paget's disease. Intravenous EHBP caused a more rapid increase in plasma P sub(i), but maximum hyperphosphatemia was not observed until 7-11 days after treatment commenced. It is therefore unlikely that this effect is due to an immediate action of EHBP on the luminal face of the renal brush border P sub(i) transporter. After 2 weeks of oral EHBP, the increase in the P sub(i) concentration in patients' erythrocytes was 31% compared with 64% in plasma. In blood platelets and leukocytes, negligible changes in cellular P sub(i) occurred.