Zoledronic acid sequential to teriparatide may promote greater inhibition of bone resorption than zoledronic acid alone.

BACKGROUND

Teriparatide (TPTD) should be followed by an antiresorptive to maximize bone mineral density gain and anti-fracture protection. Infrequent zoledronic acid (ZOL) administration has demonstrated effectiveness. The duration of ZOL effect following TPTD is unknown.

OBJECTIVE

To evaluate the effect of ZOL on bone resorption marker in a post-TPTD ZOL-alone scenario in osteoporotic patients.

DESIGN

Retrospective cohort study.

METHODS

Patients treated with TPTD followed by ZOL (TPTD-ZOL) or with a single ZOL infusion were identified in the database of a tertiary referral center. Clinical and laboratory data, including C-terminal telopeptide of type I collagen (CTX) following ZOL treatment, were compared.

RESULTS

Twenty-six patients (93% women) treated with TPTD-ZOL and 41 with ZOL were comparable in age (median 70.1 69.6 years,  = 0.6) and sex. Timing of CTX measurement post-ZOL was the same, median 1.0 year. CTX was lower following TPTD-ZOL (median 142.1 184.2 pg/mL,  = 0.005). In a multivariable regression model (controlled for baseline characteristics), pretreatment with TPTD strongly predicted CTX <150 pg/mL, 1 year following ZOL (odds ratio = 7.5, 95% CI 1.3-58.1,  = 0.03). In a subgroup with sequential CTX measurements following one ZOL, significantly lower levels persisted in the TPTD-ZOL group for a median of 4.4 years follow-up.

CONCLUSION

ZOL-administered sequential to TPTD yielded deeper and more prolonged bone resorption suppression than ZOL alone. Prospective data are needed to confirm whether in a sequential treatment scenario, subsequent ZOL dosing interval should be less frequent.