4CPS-235 Assessment of therapeutic drug monitoring in outpatient parenteral antimicrobial therapy (OPAT) in paediatric patients

<h3>Background and Importance</h3> Outpatient parenteral antimicrobial treatment (OPAT) allows intravenous antimicrobial administration at home, providing an alternative to inpatient care that particularly benefits paediatric patients and their caregivers. Paediatric population has significant intra- and inter-individual variability in drug exposure and underrepresentation in clinical trials, leading to an increased drug-associated toxicity risk. Thus, proactive therapeutic drug monitoring (TDM) may optimise dosages, enhancing efficacy while minimising adverse effects. <h3>Aim and Objectives</h3> To determine how many OPAT episodes in paediatric patients underwent TDM out of those that could benefit from it. Moreover, to evaluate the alteration of any laboratory parameters related to antimicrobial toxicity. <h3>Material and Methods</h3> Retrospective, single-centre study involved paediatric patients (&lt;18 years) on OPAT from January 2019 to December 2023. Patients treated with aminoglycosides, linezolid, teicoplanin and voriconazole were considered TDM candidates. Demographic, clinical, analytical, OPAT episode outcome and TDM variables were collected. <h3>Results</h3> The study included 24 patients, 8 (33.3%) females, with a mean age of 11.8 (±5.5) years at the onset of the episode. Most patients belonged to the following departments: pneumology (16.7%), paediatric liver transplant (33.3%), cystic fibrosis (16.7%) and oncohaematology (12.5%). The median treatment duration was 15 days (IQR 12.5–20.5). A total of 243 OPAT episodes were reviewed, of which 39 (16.0%) had TDM indication. However, TDM was only performed in 12 (30.8%) episodes. Aminoglycosides were involved in 18 episodes with five (27.8%) undergoing TDM; teicoplanin in 16, with two (12.5%) underwent TDM; linezolid in three, with one (33.3%) subjected to TDM; and voriconazole in five, all of which were monitored (100.0%). Among the episodes subjected to TDM, five (41.7%) showed out-of-range values in the initial assessment. Of the 39 episodes that could have benefited from TDM, nine (23.1%) were prematurely discontinued, of which four received TDM. Regarding potential drug related toxicity, analytical results were available for 26 (66.7%) episodes, with 18 (69.2%) exhibiting out-of-range values. Among these, three episodes suffered hepatic alterations (two treated with voriconazole, one with teicoplanin) and one renal alteration (treated with aminoglycosides) along the episode, with TDM conducted in three of them. <h3>Conclusion and Relevance</h3> TDM is performed in a limited number of paediatric OPAT episodes, often revealing out-of-range values. Furthermore, despite analytical monitoring, altered parameters persist, highlighting the need for toxicity surveillance along the episodes to enhance patient safety and optimise treatment efficacy. <h3>References and/or Acknowledgements</h3> <h3>Conflict of Interest</h3> No conflict of interest