Protracted use, up to 6 years, of an oral aminobisphosphonate in patients with established osteoporosis

In osteoporotic women (n:163), 63.8 (+/-8.1) years old and 15.2 (+/-8.3) years since menopause, oral (200mg/day) pamidronate was administered during protracted periods, up to 6 years. During the first 4 years of therapy significant increases from basal in both, lumbar spine and femoral neck were reported (p<0.01). Patients who underwent to 5-6 years of treatment also showed positive results in both skeletal sites. Whole body mineral content estimated a 23,8g/year mean gain during a 4-year period. Biochemical bone markers of resorption and formation reflected a variable degree of bone turnover decrease. Such changes were more pronounced at the beginning, and remained steady after the first year of continuous therapy. Calcemia remained between normal range without any hypocalcemic episode being reported. Phosphatemia, within normal range, showed a smooth trend to increase. PTH remained within normal range and vitamin D tended to slightly increase. The total number of new bone fractures and total number of patients with new fractures were less frequent during the pamidronate treatment period than before (p<0.01). Indeed, the relative risk (RR) of fracture was estimated comparing the treatment lapse, 495 patient/year, vs a pretreatment period of 1,814 patient/year. Overall RR resulted less than 1 (RR = 0.83; CI 95% = 0.53-1.26). In total, hip, forearm and "other" fractures, RR was also less than 1 and remained over 1 in vertebral fractures. The latter can be explained because our sample started its treatment probably in a period of increased spine crushing. Overall fracture results, in a sample of patients as own controls and in spite of differences in ages, suggested that during treatment, patients improved their skeletal biomechanical competence, mainly in sites where cortical bone plays a meaningful role, as in femoral neck. It is concluded that pamidronate is an effective tool to ameliorate the skeletal conditions of postmenopausal osteoporotic women.