Effects of PTH and alendronate on type I collagen isomerization in postmenopausal women with osteoporosis: the PaTH study.
Fracture efficacy of PTH and alendronate (ALN) is only partly explained by changes in BMD, and bone collagen properties have been suggested to play a role. We analyzed the effects of PTH(1-84) and ALN on urinary alphaalpha/betabeta CTX ratio, a marker of type I collagen isomerization and maturation in postmenopausal women with osteoporosis. In the first year of the previously published PaTH study, postmenopausal women with osteoporosis were assigned to PTH(1-84) (100 microg/d; n = 119), ALN (10 mg/d; n = 60), or PTH and ALN together (n = 59). We analyzed patients on ALN alone (n = 60) and a similar number of patients assigned to PTH alone (n = 63). During the second year, women on PTH in the first year were reallocated to placebo (n = 31) or ALN (n = 32) and women with ALN continued on ALN. During the first year, there was no significant change in alphaalpha/betabeta CTX ratio with PTH or ALN. At 24 mo, there was a marked increase of the alphaalpha/betabeta CTX ratio in women who had received PTH during the first year, followed by a second year of placebo (median: +45.5, p < 0.001) or ALN (+55.2%, p < 0.001). Conversely, the alphaalpha/betabeta CTX ratio only slightly increased (+16%, p < 0.05) after 2 yr of continued ALN. In conclusion, treatment with PTH(1-84) for 1 yr followed by 1 yr of placebo or ALN may be associated with decreased type I collagen isomerization. The influence of these biochemical changes of type I collagen on bone fracture resistance remains to be studied.
Garnero
Patrick
P
INSERM Research Unit 664, Lyon, France
Bauer
Doug C
DC
Mareau
Emmanuel
E
Bilezikian
John P
JP
Greenspan
Susan L
SL
Rosen
Clifford
C
Black
Dennis
D
D000368:Aged; D000369:Aged, 80 and over; D019386:Alendronate / Q000494:pharmacology / Q000627:therapeutic use*; D015415:Biomarkers / Q000378:metabolism; D001842:Bone and Bones / Q000187:drug effects / Q000378:metabolism; D024042:Collagen Type I / Q000737:chemistry* / Q000652:urine; D005260:Female; D006801:Humans; D007536:Isomerism; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000188:drug therapy* / Q000652:urine; D010281:Parathyroid Hormone / Q000494:pharmacology / Q000627:therapeutic use*; D010919:Placebos
D015415:Biomarkers; D024042:Collagen Type I; D010281:Parathyroid Hormone; D010919:Placebos; D019386:Alendronate