Safety of daily teriparatide treatment: a post hoc analysis of a Phase III study to investigate the possible association of teriparatide treatment with calcium homeostasis in patients with serum procollagen type I N-terminal propeptide elevation
Authors Yamamoto T, Tsujimoto M, Sowa H
Received 26 February 2015
Accepted for publication 15 April 2015
Published 6 July 2015 Volume 2015:10 Pages 1101—1109
Checked for plagiarism Yes
Review by Single-blind
Peer reviewer comments 4
Editor who approved publication: Dr Richard Walker
Takanori Yamamoto,1 Mika Tsujimoto,2 Hideaki Sowa1
1Medical Science, Lilly Research Laboratories, Medicines Development Unit Japan, 2Asia Pacific Statistical Science-Japan, Science and Regulatory Affairs, LRL MDU-Japan, Eli Lilly Japan K.K, Kobe, Hyogo, Japan
Objective: Serum procollagen type I N-terminal propeptide (PINP), a representative marker of bone anabolic action, is strongly related to bone mineral density during teriparatide therapy. This post hoc study analyzed data from a Phase III study (ClinicalTrials.gov identifier NCT00433160) to determine if there was an association between serum PINP elevation and serum calcium concentration or calcium metabolism-related disorders.
Research design and methods: Japanese subjects with osteoporosis at high risk of fracture were randomized 2:1 to teriparatide 20 µg/day (n=137) or placebo (n=70) for a 12-month double-blind treatment period, followed by 12 months of open-label teriparatide treatment of all subjects.
Main outcome measures: Serum PINP levels were measured at baseline, and after 1, 3, 6, 12, 18, and 24 months of treatment. Serum calcium levels were measured at baseline, and after 1, 3, 6, 9, 12, 15, 18, 21, and 24 months of treatment.
Results: Serum PINP increased from baseline to 1 month of treatment and then remained high through 24 months. Twenty-eight of 195 subjects experienced PINP elevations >200 µg/L during teriparatide treatment. Serum calcium concentration in both the teriparatide and placebo groups remained within the normal range. There was no clinically relevant difference in serum calcium concentration between subjects with PINP >200 µg/L and subjects with PINP ≤200 µg/L. Two subjects experienced hypercalcemia and recovered without altering teriparatide treatment. Adverse events possibly related to calcium metabolism disorders included periarthritis calcarea (one subject) and chondrocalcinosis pyrophosphate (two subjects), but neither was accompanied with a significant increase in PINP or serum calcium concentration.
Conclusion: Although the moderate size of this study prevented statistical analysis of any potential association between calcium metabolism-related disorders and elevated PINP, this analysis suggests that there was no association between serum PINP elevation during daily teriparatide treatment and serum calcium concentration or calcium metabolism-related disorders in Japanese subjects.
Keywords: teriparatide, osteoporosis, hypercalcemia, procollagen type I N-terminal propeptide, bone metabolism markers
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