Aim dalbavancin, a lipo-glycopeptide antibiotic effective against Gram-positive bacteria (including methicillin-resistant Staphylococcus aureus ), allows extended dosing interval due to its peculiar pharmacokinetics. Despite being registered for treatment of acute skin infections, off-label use has shown promise in various settings, particularly in osteo-articular infections. This study aims to assess dalbavancin's pharmacological efficacy and its safety and clinical success in patients treated according to personalized schedules guided by Therapeutic Drug Monitoring (TDM), particularly in long-term therapies. Methods non-interventional, retrospective, single-center pharmacological study. We included adult patients with at least one dalbavancin TDM determination from July 1, 2022 to February 1, 2024 and treated with outpatient parenteral antimicrobial therapy. We recorded dalbavancin trough concentration (Cmin) and its peak concentration (Cmax) and employed log-linear regression models to predict the timing of dalbavancin dosing, aiming to sustain Cmin levels above 4 or 8.04 mg/L, according to recent literature. Data regarding index infections, patients’ characteristics, outcomes, and adverse events were also collected. Results we included 32 patients, whose clinical and microbiological characteristics are depicted in Table 1 . Regarding the primary outcome , 132/134 (98.5%) trough concentration was &gt;4 mg/L, while 112/134 (83.6%) was &gt;8.04 mg/L. For the secondary outcomes , 2/32 patients experienced an adverse event correlated to dalbavancin: (i) exanthema one week after the start of therapy and (ii) exanthema, conjunctivitis, angioedema, and nausea one month after the start of therapy. Moreover, we observed 4/32 clinical unsuccess (one failure during treatment, one relapse after the end of therapy, one switch to another antibiotic, and one isolation of non-susceptible microorganism). Conclusions a TDM-based approach with the use of a log-linear regression model allows a more precise timing of dalbavancin administration by maintaining sufficient concentration of circulating drugs. This approach is promising for infections requiring a long-term treatment, such as orthopedic infection where source control is not possible. For any tables or figures, please contact the authors directly.

A THERAPEUTIC DRUG-MONITORING APPROACH FOR DALBAVANCIN (MONTALBANO)