The Comparison of Ibandronate and Zoledronic Acid After Denosumab Discontinuation

Overview

This study is a prospective, multicenter, open-label, randomized non-inferiority trial comparing intravenous ibandronate and zoledronic acid as sequential therapy after denosumab discontinuation in postmenopausal women with osteoporosis. This trial primarily targets patients with short-term denosumab exposure (less than three years) and is conducted as a preliminary investigation. The findings are expected to provide foundational evidence to inform the design of future studies assessing sequential therapies following longer-term denosumab treatment.

Osteoporosis has been recognized by the World Health Organization (WHO) as the second most prevalent global epidemic disease, following coronary heart disease. Untreated osteoporosis may lead to a vicious cycle of recurrent fractures, resulting in disability and even mortality. In clinical practice, antiresorptive agents are commonly used as first-line therapy. Denosumab is widely preferred due to its convenient administration and potent suppression of bone turnover. However, its antiresorptive effect is reversible; discontinuation of denosumab is associated with rebound increases in bone turnover markers (BTMs) and rapid bone mineral density (BMD) loss. Therefore, subsequent antiresorptive therapy is required to prevent fracture occurrence. Zoledronic acid has been shown to effectively suppress post-denosumab rebound bone turnover and is currently considered the standard sequential treatment following denosumab discontinuation. The objective of this study is to demonstrate that ibandronate, when used as a sequential therapy after denosumab discontinuation, provides protection comparable to zoledronic acid in patients with short-term denosumab exposure (\< 3 years). This study aims to generate preliminary clinical evidence to support future trials and to offer an alternative post-denosumab treatment strategy in clinical practice. Participants will receive one year of ibandronate or zoledronic acid therapy, initiated 6 months (± 1 week) after the last dose of denosumab, followed by a total of two years of follow-up. Eligible participants will be randomized in a 1:1 ratio, with an estimated sample size of 26 patients per group.