Postmarketing surveillance of the safety of cyclic etidronate

To evaluate the safety of cyclic etidronate in routine clinical practice, we obtained information from 550 general practices in the United Kingdom that provide the medical records to the General Practice Research Database. A group of 7977 patients taking cyclic etidronate and two age-, gender-, and practice-matched control groups, one with osteoporosis and one without, were analyzed. For the group taking cyclic etidronate, the average age was 71.6 years and follow-up was 10,328 person-years. Conditions that do not induce osteoporosis generally occurred in these patients at a rate comparable to that in the control groups. The incidence of osteomalacia was low and comparable between patients taking cyclic etidronate and controls with osteoporosis. No medically significant increases in frequency were observed among patients taking cyclic etidronate for a broad group of diseases that may potentially be induced by exposure to the drug. These data support the favorable risk:benefit ratio of cyclic etidronate.