CHANGES IN BIOCHEMICAL MARKERS AND BONE MASS AFTER WITHDRAWAL OF IBANDRONATE TREATMENT - PREDICTION OF BONE MASS CHANGES DURING TREATMENT

The study was a 1 year randomized, double-blind, placebo-controlled st udy of ibandronate treatment in post menopausal, osteopenic women. Par ticipants were followed for 1 pear after withdrawal of treatment. All women were at least 10 years past menopause and had a baseline bone mi neral density (BMD) at the distal forearm at least 1.5 standard deviat ions below the premenopausal mean peak value, A total of 141 women (78 %) completed the first year, and 119 women (66%) the second year of th e study. The dose-response data of the first year have been published previously (Ravn et al, Bone 19;527-533;1996). In this study, we analy zed the biochemical markers as predictors of response in bone mass dur ing ibandronate treatment, and report withdrawal data from the last ye ar of the study, when ibandronate was discontinued. The relative chang e in the biochemical markers was significantly correlated to the respo nse in BMD, At 12 months, the r values ranged from -0.29 to -0.47 (p < 0.01) and were highest for CrossLaps (uCL) and osteocalcin (OCN-MID). The quartiles of women with the most reduced concentrations of uCL an d OCN-MID during treatment showed a 360-430% higher response in BMD co mpared to quartiles with less reduced concentrations (p < 0.01), Durin g the withdrawal period, uCL and alkaline phosphatase (AP) returned to baseline values 12 months after discontinuation of treatment in all g roups, whereas OCN-MID and bone-specific AP were still reduced 10%-25% in the groups previously treated with the highest doses of ibandronat e (1.0-5.0 mg) (p < 0.01), In the withdrawal period, BMD decreased equ ally in all groups (analysis of variance; not significant); with a lin ear rate of 2%/year on average (p < 0.05 to < 0.001) at the spine and femur. In conclusion, uCL and OCN-MID can be used to predict the respo nse in bone mass during ibandronate treatment. The bone loss that resu mes after withdrawal of ibandronate treatment is of a magnitude simila r to that of normal postmenopausal bone loss. (C) 1998 by Elsevier Sci ence Inc. All rights reserved.