Changes in urinary NTX levels in patients with primary osteoporosis undergoing long-term bisphosphonate treatment.
BACKGROUND
Bisphosphonates, antiresorptive drugs, are widely used to treat osteoporosis patients. However, recent reports indicated that several osteoporosis patients who underwent long-term bisphosphonate therapy subsequently developed severe suppression of bone turnover. We investigated whether urinary crosslinked N-telopeptide of type I collagen (NTX), a bone resorption marker, in osteoporosis patients was highly suppressed during long-term treatment with alendronate or risedronate.


METHODS
We investigated 87 primary osteoporosis outpatients who were treated with alendronate or risedronate for more than 2 years. All patients were women, with an average age of 72.6 years. Altogether, 49 patients were treated with alendronate and 38 with risedronate, and the average administration period was 3.5 years. We defined high suppression as NTX being reduced <9.3 nmol bone collagen equivalent/mmol.Cr and a 35% decrease from baseline.


RESULTS
In total, 11 of 87 patients (12.6%) had high NTX suppression based on the above criteria. The incidences of high suppression of NTX at 1,2,3,and 4 years after starting the treatment were 0%, 1.1%, 11.9%, and 4.7%, respectively. The average age, bone mineral density, and NTX values at baseline and the administration period were not associated with high suppression of NTX during alendronate or risedronate treatment. Regarding suppression of NTX during long-term treatment, there was no significant difference between alendronate and risedronate.


CONCLUSIONS
The results suggested that long-term treatment with bisphosphonates necessitates careful follow-up of the patients.
Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, South-1, West-16, Chuo-ku, Sapporo, 060-8543, Japan.
Kousuke
K
Iba
Junichi
J
Takada
Naoko
N
Hatakeyama
Yasuhiro
Y
Ozasa
Takuro
T
Wada
Toshihiko
T
Yamashita
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019386:Alendronate / Q000627:therapeutic use; D050071:Bone Density Conservation Agents / Q000627:therapeutic use*; D024042:Collagen Type I / Q000652:urine*; D004164:Diphosphonates / Q000627:therapeutic use*; D012968:Etidronic Acid / Q000031:analogs & derivatives / Q000627:therapeutic use; D005260:Female; D006801:Humans; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000188:drug therapy / Q000652:urine*; D010455:Peptides / Q000652:urine*; D000068296:Risedronic Acid
D050071:Bone Density Conservation Agents; D024042:Collagen Type I; D004164:Diphosphonates; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D000068296:Risedronic Acid; D012968:Etidronic Acid; D019386:Alendronate