title: Effects of a single injection of teriparatide on bone turnover markers in postmenopausal women.
abstract: This study investigated the effects of a single administration of teriparatide on bone turnover markers in postmenopausal women. Teriparatide caused a transient increase in bone resorption and inhibition of bone formation followed by a subsequent increase in bone formation and a decrease in resorption that lasted at least 1 week.
  
  
  BACKGROUND
  This study aims to investigate the effects of a single subcutaneous administration of teriparatide on bone turnover markers to elucidate why once weekly intermittent administration of teriparatide is effective on osteoporosis.
  
  
  METHODS
  Pharmacokinetics and calcium metabolism and bone turnover parameters were measured in 30 postmenopausal women after two doses of teriparatide (28.2 or 56.5 μg injection) or placebo in a randomized, double-blind, placebo-controlled study.
  
  
  RESULTS
  Teriparatide plasma concentration increased in a dose-dependent manner, and the maximum concentration was achieved 1 h after injection. Serum levels of calcium and phosphorus were transiently increased and decreased after teriparatide injection, respectively. Calcium metabolism returned to baseline levels 24 h later. Two days after injection, the serum level of 1,25-dihydroxy vitamin D was increased by ~80 % from baseline for both doses of teriparatide. Serum levels of osteocalcin and procollagen type I N-terminal propeptide decreased during the first 24 h followed by a ~10 % increase for 14 days. The serum level of cross-linked N-telopeptide (NTX) of type I collagen increased during the first 24 h followed by a 10 to 12 % dose-dependent suppression from baseline for 14 days. Urinary cross-linked C-telopeptide of type I collagen changes occurred in the same direction as serum NTX, but not dose dependently.
  
  
  CONCLUSIONS
  A single administration of teriparatide caused an immediate, transient increase in bone resorption and inhibited bone formation followed by an increase in bone formation and decrease in resorption for ≥1 week. These findings may provide proof for the effect of a once-weekly regimen of teriparatide on bone turnover.
authors.affiliation: Department of Internal Medicine, Research Institute and Practice for Involutional Diseases, 1610-1 Meisei, Misato, Azumino, Nagano, 399-8101, Japan. ripid@fc4.so-net.ne.jp
authors.forename: M
authors.initials: M
authors.lastname: Shiraki
authors.forename: T
authors.initials: T
authors.lastname: Sugimoto
authors.forename: T
authors.initials: T
authors.lastname: Nakamura
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood / Q000652:urine; D050071:Bone Density Conservation Agents / Q000008:administration & dosage* / Q000009:adverse effects / Q000097:blood / Q000494:pharmacology; D016723:Bone Remodeling / Q000187:drug effects*; D001862:Bone Resorption / Q000378:metabolism / Q000517:prevention & control; D002118:Calcium / Q000097:blood / Q000652:urine; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D007279:Injections, Subcutaneous; D008875:Middle Aged; D010012:Osteogenesis / Q000187:drug effects; D017698:Postmenopause / Q000378:metabolism / Q000502:physiology*; D019379:Teriparatide / Q000008:administration & dosage* / Q000009:adverse effects / Q000097:blood / Q000494:pharmacology
chemical_list: D015415:Biomarkers; D050071:Bone Density Conservation Agents; D019379:Teriparatide; D002118:Calcium