Monthly ibandronate suppresses serum CTX-I within 3 days and maintains a monthly fluctuating pattern of suppression.
Bone turnover markers such as serum C-terminal cross-linking telopeptide of type I collagen (CTX-I) can be used to assess drug efficacy in osteoporosis. This study evaluated the pattern of CTX-I suppression in postmenopausal osteoporotic women receiving ibandronate. Ibandronate decreased serum CTX-I levels within 3 days of therapy initiation. Over 6 months, the levels remained suppressed below baseline.


BACKGROUND
This randomized, double-blind, placebo-controlled study evaluated the rapidity of onset and pattern of suppression of the bone resorption marker serum CTX-I in women with postmenopausal osteoporosis (PMO) who received once-monthly oral ibandronate.


METHODS
Women diagnosed with PMO received once-monthly oral ibandronate (150 mg) or placebo for 6 months. Serum CTX-I was measured at baseline and after study dose administration on day 3 (month 1 only) and days 7, 14, 21, and 28 (months 1-6). Bone-specific alkaline phosphatase was measured on days 7 and 28 (months 1-6).


RESULTS
This study enrolled 67 women: 49 received ibandronate, 17 received placebo, and one took no study drug. At day 3, median reduction in serum CTX-I from baseline was 70.2% with ibandronate and 6.0% with placebo (difference, -64.2%; 95% confidence interval, -80.3% to -46.2%; p < 0.0001). In women receiving ibandronate, serum CTX-I levels remained consistently below baseline, exhibiting a regular monthly fluctuating pattern of suppression over 6 months. Ibandronate was well-tolerated.


CONCLUSIONS
Monthly ibandronate decreased serum CTX-I within 3 days. Over 6 months, in women receiving once-monthly ibandronate, serum CTX-I remained suppressed below baseline. A monthly fluctuation, related to time from last dose, was observed.
Binkley
N
N
Osteoporosis Clinical Center and Research Program, University of Wisconsin, 2870 University Avenue, Suite 100, Madison, WI 53705, USA. nbinkley@wisc.edu
Silverman
S L
SL
Simonelli
C
C
Santiago
N
N
Kohles
J D
JD
Dasic
G
G
Sunyecz
J A
JA
D050071:Bone Density Conservation Agents / Q000627:therapeutic use*; D016723:Bone Remodeling / Q000187:drug effects*; D001862:Bone Resorption / Q000097:blood / Q000188:drug therapy* / Q000517:prevention & control; D024042:Collagen Type I / Q000097:blood*; D004164:Diphosphonates / Q000627:therapeutic use*; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D000077557:Ibandronic Acid; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000097:blood / Q000188:drug therapy*; D010455:Peptides / Q000097:blood*; D011446:Prospective Studies; D016896:Treatment Outcome
D050071:Bone Density Conservation Agents; D024042:Collagen Type I; D004164:Diphosphonates; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D000077557:Ibandronic Acid