Administration of teriparatide for four years cyclically compared to two years daily in treatment Naïve and alendronate treated women.

Purpose: We evaluated if equivalent doses of TPTD given cyclically over 4-years could increase BMD >2-years of daily TPTD in 2 cohorts of women; previously untreated (Rx-Naïve) and women previously treated with ALN (ALN-Rx).

Methods: In Rx-Naïve, women were randomized to daily TPTD for 24 months (Daily; n = 23) or cyclic TPTD for 48 months (3 months on, 3 months off; Cyclic; n = 25). In ALN-Rx, women were randomized to continued ALN plus daily TPTD for 24 months, followed by ALN alone for 24 months (Daily; n = 21) or TPTD for 48 months (3 months on, 3 months off) while ALN was continued (Cyclic; n = 20). BMD (DXA) was measured at spine (LS), total hip (TH) and femoral neck (FN). The primary analysis compared 4 years of cyclic therapy to 2 years of daily therapy in RX-naïve and ALN-RX cohorts.

Results: In Rx-Naïve, BMD changes at 24 months after Daily TPTD vs. 48 months after Cyclic TPTD were: LS 8.6% vs. 6.9%; TH 2.5% vs. 2.6%, and FN 1.6% vs. 2.2%. None of the BMD changes differed significantly between groups but all changes were significant over time within each group (p < 0.01 except for FN where p = 0.17 Daily; p = 0.09 Cyclic). In ALN-Rx, BMD changes at 24 months after Daily TPTD vs. 48 months after Cyclic TPTD were: LS 7.5% vs. 7.2%; TH 3.8% vs. 4.1%, and FN 3.2% vs. 2.5%. There were no differences between groups but all changes were significant within each group (p < 0.01).

Conclusion: The same cumulative dose of TPTD given cyclically for 4-years, does not increase BMD more than standard daily TPTD over 2-years in either Rx-Naïve or ALN-Rx women.

Trial Registration: NCT00668941.