Pilot Pharmacokinetic Study in Healthy Adults Using Intravascular Microdialysis Catheters Modified for Use in Paediatric Patients to Assess Vancomycin Blood Levels

BACKGROUND AND OBJECTIVE: Exhaustive pharmacokinetic (PK) studies in paediatric patients are unavailable for most antibiotics and feasibility of PK studies is limited by challenges, such as low blood volume and venipuncture-related pain. Microdialysis (MD) represents a promising method to overcome these obstacles. The aim of this proof-of-concept study was to develop and validate modified MD catheters that can be used to obtain concentration–time profiles of antibiotics in paediatric patients. METHODS: Following extensive in vitro MD experiments, a prospective open-labelled study in ten healthy adult volunteers (HVs) was conducted. Subjects received a single intravenous dose of 1000 mg vancomycin, then plasma and intravascular microdialysate were sampled over 24 h. In vivo MD probe calibration was conducted using the retrodialysis technique. Plasma protein binding was measured using ultrafiltration. Confirmation of the measurements was performed using a Bland-Altman plot, relevant PK parameters were calculated, and a pharmacometric model was established. RESULTS: No safety issues were encountered. The concentration–time curves of microdialysate and plasma measurements showed good alignment. The Bland-Altman plot yielded a mean bias of 0.19 mg/L and 95% limits of agreement of − 9.34 to 9.71 mg/L. A two-compartment model best described plasma PK, model-based estimates for recovery of the MD probes being in high agreement with the observed values. Quantified estimates of fraction unbound were comparable between plasma and microdialysate (p = 0.56). CONCLUSIONS: An innovative MD catheter that can be inserted into small intravenous lines was successfully developed and applied in HV. This proof-of-concept study is encouraging and opens the way to further experiments leading towards future use of MD in paediatric patients. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s40262-022-01190-7.