Validated HPLC method for ceftriaxone from dried blood spots for pharmacokinetic studies and therapeutic drug monitoring in neonatal population.

Background: Pharmacokinetic evaluation is essential for the precise dosing of ceftriaxone in neonates. There is a need for developing a sensitive, affordable and convenient analytical method that can estimate ceftriaxone from dried blood spot (DBS) samples of neonates. Method: An HPLC-UV method was developed and validated as per ICH M10 for ceftriaxone from DBS and plasma using an Inertsil-ODS-3V column with gradient elution. DBS samples were extracted with methanol. Clinical validation was performed using neonatal samples. Results: The developed plasma- and DBS-based-HPLC method were linear from 2-700 µg/ml and 2-500 µg/ml, respectively, for ceftriaxone. Bland-Altman analysis indicated a strong interconvertibility between the plasma and DBS assays. Conclusion: Observed concentrations in clinical samples were comparable to the predicted concentrations, proving the clinical validity of the method.

Neonatal meningitis is usually treated with the drug ceftriaxone. It is essential to determine the amount of ceftriaxone in the blood for precise dosing that is safe and effective in newborn children. Dried blood spot (DBS) sampling from a heel prick is a less invasive sample collection method for newborn children than withdrawing blood from a vein. In this study we developed a robust analytical method based on a commonly available analytical platform to measure ceftriaxone in DBS samples. The results of ceftriaxone analysis obtained using the developed DBS-based method were compared with the results of traditional plasma sample analysis to make sure that they are accurate and reproducible. The range of analysis of the method is 2­500 µg/ml, which is suitable for the measurement of ceftriaxone concentration levels in newborns' blood. The effect of varying proportions of red blood cells in whole blood (30­50%) and volume of blood (20­60 µl) applied on the DBS card were not found to influence the results. The method was validated with clinical samples from newborn children and resulted in the expected concentrations. The developed method is affordable and can be used for therapeutic drug monitoring and precise dosing of ceftriaxone in newborn children.