Therapeutic Drug Monitoring of High-dose Sulbactam in Pediatric Patients: Preliminary Data From a Prospective Observational Pharmacokinetic Study

Background: Rates of carbapenem-resistant Acinetobacter baumannii are rising in Thailand. Although high-dose (HD) sulbactam is recommended for treating carbapenem-resistant A. baumannii infections, data on plasma sulbactam concentrations in children are limited. We aimed to evaluate plasma sulbactam concentrations and pharmacokinetic-pharmacodynamic (PK-PD) target achievement in pediatric patients. Methods: Prospective study data (January–November 2023) on children (1 month–18 years) who received sulbactam every 6–8 hours were analyzed. Mid-dosing ( C mid , 50% f T) and trough ( C trough , 100% f T) concentrations were evaluated. PK-PD target achievement [50% f T > minimum inhibitory concentration (MIC), 100% f T > MIC] was evaluated using Clinical and Laboratory Standards Institute 2024 MIC cutoffs and MIC data of isolates of Acinetobacter calcoaceticus–baumannii complex from this study. Results: Thirty-five patients (median age 50 months) were categorized into standard-dose (SD) or HD groups. The geometric mean C mid was higher in the HD (41.3 mg/L) versus SD (19.5 mg/L) groups ( P = 0.006). Among 101 isolates of Acinetobacter calcoaceticus–baumannii complex, the MIC50 and MIC90 (concentrations that inhibit 50% and 90% of isolates of the A. calcoaceticus–baumannii complex) were 16 and 128 mg/L, respectively. The HD group achieved C mid >MIC50 in 87.5% of the patients compared with 63.6% in SD ( P = 0.17). Within the HD group, patients with augmented renal clearance (ARC) had lower C mid (geometric mean 31.9 mg/L) compared with non-ARC (geometric mean 63.4 mg/L) ( P = 0.04). Conclusions: HD sulbactam resulted in higher C mid and PK-PD achievement. ARC significantly compromised plasma sulbactam concentration. HD sulbactam may be preferable for treating critically ill pediatric patients and those with ARC, especially during the empirical period.