Evaluation of Serum Acetaminophen Concentration Utility for Closure of Patent Ductus Arteriosus.

Objective: Acetaminophen for patent ductus arteriosus (PDA) closure has gained popularity over the last decade; however, therapeutic drug monitoring for this indication remains uncertain. The exact timing and goal trough serum acetaminophen concentration ranges are not well defined. The purpose of our study is to evaluate the impact of therapeutic drug monitoring on both PDA closure rates and identify real-world risk of hepatotoxicity.

Methods: Retrospective single-center chart review of neonates admitted to the neonatal intensive care unit (NICU) between April 2016 and August 2022 with at least 1 serum acetaminophen concentration to monitor for PDA closure. Acetaminophen was initiated at 15 mg/kg administered intravenously every 6 hours and a trough serum concentration was obtained prior to the sixth or seventh dose. PDA closure was confirmed radiographically with corresponding provider documentation. Associations of efficacy to closure were -analyzed using descriptive statistics.

Results: Thirty-eight neonates were included in the analysis, of which 18 (47%) achieved PDA closure. First serum acetaminophen trough concentration was obtained before the seventh dose [IQR, 6-8] and ranged from undetectable (< 5 mg/L) to 30.8 mg/L. Subgroup analysis of first concentrations revealed therapeutic trough, defined as 10 to 20 mg/L, did not correlate to PDA closure (no closure median concentration = 14.7 [IQR, 13-15.6] vs closure median concentration = 15.4 [IQR, 11.4-18.5], p = 0.42), or duration of treatment. No neonate experienced acetaminophen-associated toxicity.

Conclusions: PDA closure did not correlate to serum acetaminophen trough concentration. The regimen of 15 mg/kg every 6 hours appears safe as no neonate experienced acetaminophen toxicity or discontinued treatment early.