Rapid suppression of bone resorption marker levels with ibandronate therapy in a bisphosphonate-naïve population.

This 6-mo open-label study assessed the pattern of bone turnover marker (BTM) level changes in bisphosphonate-naïve women with postmenopausal osteoporosis treated with monthly oral ibandronate 150mg and the correlation between month 1 and month 6 serum C-terminal cross-linking telopeptide of type I collagen (sCTX) levels. The following BTMs were monitored: sCTX, urinary N-terminal telopeptide of type I collagen (uNTX), serum procollagen type 1 N-terminal propeptide (PINP), serum osteocalcin (OC), and serum bone-specific alkaline phosphatase (bALP). BTM levels were measured immediately before dosing at baseline and months 1, 2, 3, and 6, and 7d after dosing at baseline and month 4. A multiple regression model was applied to determine whether month 1 sCTX response predicted month 6 sCTX change. sCTX levels declined 70% 7d after dosing at baseline and month 4. Predosing sCTX declined 55% at month 6. The pattern of uNTX reduction was similar to sCTX. Bone formation markers PINP, OC, and bALP declined gradually over time. Month 1 sCTX change was a significant predictor of Month 6 change (p=0.0001). Once monthly 150mg oral ibandronate treatment reduced BTMs in women with osteoporosis. sCTX reduction occurred within 7d and was sustained over 6mo. Month 1 sCTX predicted month 6 sCTX.