Appropriateness of loading dose and TDM in patients treated with teicoplanin: a single-centre observational retrospective cohort study comparing single-daily and thrice-weekly regimens

Objectives: To assess the appropriateness of teicoplanin loading dose and therapeutic drug monitoring (TDM) in single-daily regimen (SDR) versus thrice-weekly regimen (TWR), and to compare safety and effectiveness. Methods: This single-centre observational retrospective cohort study included adult patients treated with TDM-based teicoplanin for infections between April 2015 and December 2021. Appropriateness of loading dose and TDM, adverse events (AEs) and clinical outcomes were evaluated. A post hoc analysis assessed achievement of target TDM concentrations following appropriate loading dose. Results: Among 183 patients (103 SDR, 80 TWR), appropriate loading doses were less frequent in the SDR group [33/103 (35.9%, missing = 11) versus 56/80 (72.7%, missing = 3); P < 0.001]. First TDM was less commonly performed as recommended in the SDR group on Day 4 [89/103 (86.4%) versus 79/80 (98.8%); P = 0.002] and on Day 7 [31/103 (30.1%) versus 47/80 (58.8%); P < 0.001]. No significant differences were observed in AEs [15/103 (14.6%) versus 8/80 (10%); P = 0.38] or clinical success [60/103 (58.3%) versus 49/80 (61.3%); P = 0.681] between groups. Post hoc analysis showed that 2/16 (13%) patients with deep infections and 9/11 (82%) with non-deep infections on a TWR achieved target concentrations after loading dose. Conclusions: Higher adherence to loading dose and TDM recommendations was observed for TWR compared with SDR. However, the TWR often failed to achieve adequate TDM levels for higher targets, highlighting the need for optimized TWR loading dose strategies.