Determination of etoposide serum concentrations in small pediatric samples by an improved method of reversed-phase...

Area of Science:

• Pharmacology
• Analytical Chemistry
• Pediatric Oncology

Background:

• Existing etoposide measurement assays require large sample volumes, limiting their use in pediatric settings.
• Accurate monitoring of etoposide serum levels is crucial for optimizing treatment in pediatric cancer patients.

Purpose of the Study:

• To develop and validate an improved, sensitive method for determining etoposide serum concentrations in pediatric patients.
• To establish a practical assay suitable for routine use in a pediatric oncology practice.

Main Methods:

• Development of a high-performance liquid chromatography (HPLC) method with fixed-wavelength ultraviolet detection.
• Extraction of etoposide from small serum samples (0.2 ml) using dichloromethane.
• Quantification using diphenylhydantoin as an internal standard.

Main Results:

• The improved assay demonstrated high extraction efficiency (85.7% for etoposide).
• The method achieved a lower limit of detection of 50 ng/ml and a linear quantitation range of 0.05-50 microg/ml.
• Each measurement was completed rapidly, within 5 minutes.

Conclusions:

• The developed HPLC assay provides a sensitive and efficient method for routine etoposide serum level measurement in pediatric oncology.
• This assay addresses the limitations of previous methods by requiring significantly smaller sample volumes.
• The findings support the clinical utility of this assay for therapeutic drug monitoring in children undergoing etoposide treatment.