Safety and efficacy of a novel salmon calcitonin (sCT) technology-based oral formulation in healthy postmenopausal women: acute and 3-month effects on biomarkers of bone turnover.

Unlabelled: Oral administration of calcitonin could improve compliance to long-term treatment. Efficacy and safety of a novel oral formulation was assessed on 277 postmenopausal women. The results show (1) effective enteral absorption, (2) marked inhibition of bone resorption with minimal alteration of formation, and (3) reproducibility of responses over 3 months.

Introduction: We have recently introduced an Eligen technology-based oral formulation of salmon calcitonin (sCT) that effectively delivers the hormone to the circulation. The efficacy and safety during longer-term administration, however, has not been investigated in the target population.

Materials And Methods: This was a multicenter, randomized, double-blind, placebo-controlled, dose-ranging clinical trial including 277 healthy postmenopausal women 55-85 years of age. Women received treatment with either daily (0.15, 0.4, 1.0, or 2.5 mg) or intermittent doses (1.0 mg, every other day) of sCT combined with the delivery agent (8-[N-2-hydroxi-5-chloro-benzoyl]-amino-caprylic acid, 200 mg) or placebo for 3 months. All participants received 1,000 mg calcium plus 400 IU vitamin D daily throughout the study. Efficacy parameters were the acute and/or pre-dose changes in serum and urinary C-terminal telopeptide of type I collagen (CTx), N-mid osteocalcin (OC), bone-specific alkaline phosphatase (BSALP), calcium, and parathyroid hormone (PTH) measured by established immunoassays.

Results: After the first dose, sCT evoked dose-dependent decreases in serum CTx (-60.8% to -81.8% from baseline) compared with placebo, reaching nadirs 2-3 h after drug intake, after which, gradual increases were observed. The simultaneous acute changes in OC were statistically nonsignificant. Area under the curve (AUC) of serum CTx responses at months 1 and 3 showed strong correlation with those at baseline (both r = 0.78, p < 0.001). At month 3, the placebo-corrected changes in the pre-dose value of serum and urinary CTx were significant only in the 1.0-mg dose group (-18.9% and -20.5%, respectively, p < 0.05). The placebo-corrected change in OC was -8.6 (p = 0.09), whereas the change in BSALP was -7.3 (p = 0.02). The oral formulation was well tolerated, with mild to moderate gastrointestinal and skin manifestations apparent mainly in the high-dose groups.

Conclusion: The results of this 3-month trial show that the novel Eligen technology-based oral formulation of sCT has potential to become a safe and effective treatment for postmenopausal bone loss. Future trials are needed to assess the impact of long-term administration on changes in BMD and fracture risk.