Proactive Therapeutic Drug MONiToring to Guide Suppressive Antibiotic Therapy with DALBAvaNcin ( > 12 weeks) in Osteoarticular Infections (MONTALBANO)

Introduction: Long-term dalbavancin use is increasingly adopted off-label for osteoarticular infections (OAIs), but data on administration timing and long-term effects beyond 12 weeks are scarce. This study evaluated the pharmacological efficacy of proactive therapeutic drug monitoring (TDM) to optimize dalbavancin administration. Methods: This single-center, retrospective study included adult OAI patients treated with ≥4 doses of dalbavancin from July 2022 to October 2024. Initial doses were given on days 1, 8, and 43. From the third dose onward, Cmin and Cmax values informed dosing schedules via log-linear regression models, targeting  mg L−1. The primary outcome was the pharmacological efficacy of dalbavancin, assessed by the proportion of patients with  mg L−1 and ≥4 mg L−1 after the third dose. Clinical outcomes and safety data were collected as descriptive data. Results: A total of 33 patients provided 118 Cmin determinations. Pharmacological efficacy was achieved in 93118 (78.8 %) and 114118 (96.6 %) determinations for Cmin thresholds of ≥8 mg L−1 and ≥4 mg L−1, respectively. Efficacy improved when considering only determinations at the correct timing. A total of 18 (54.5 %) patients are still in treatment, while 11 (33.3 %) completed therapy with clinical success. Three patients experienced a relapse after the end of the treatment, while one patient experienced failure, and no adverse events were reported. Conclusions: Dalbavancin is a viable option for prolonged OAI management when other therapies are unavailable or high-risk. Proactive TDM effectively supports this approach by ensuring adequate drug exposure while preventing accumulation.