The use of cyclical etidronate in osteoporosis: changes after completion of 3 years treatment.

An open study over 4 yr has been conducted to determine the efficacy of cyclical etidronate treatment in patients from the community, with osteoporosis and in those at risk who attended an osteoporosis clinic; and to clarify whether bone remodelling returns to baseline values and bone mass is maintained after completion of a 3 yr course of treatment. One hundred and fifteen female patients, with and without osteoporotic fractures (n = 62 and 53, respectively), who were unsuitable for, or declined, hormone replacement therapy, received 3 yr cyclical etidronate treatment (400 mg etidronate disodium for 14 days followed by 500 mg elemental calcium for 76 days repeated in 3-monthly cycles) and 1 yr treatment-free follow-up. There was an overall increase in lumbar spine bone density (patients without fractures 2.6%, P < 0.001; with fractures 4.3%, P < 0.01) with minimal change at the femoral neck. The serum concentration of bone formation markers (osteocalcin and bone alkaline phosphatase) fell in response to treatment to a nadir at 6/12 (75 and 83% of baseline, respectively; P < 0.001). A cohort of patients (n = 29), 14 without fractures and 15 with fractures, was studied in more detail. After completion of treatment in the following treatment-free year, there was a resurgence of bone turnover (osteocalcin and bone alkaline phosphatase 117 and 122% of baseline, respectively; P < 0.05 and P < 0.01) with some evidence of maintenance of bone mass already gained. There is no evidence of persistent suppression of bone turnover after completion of treatment.