Dried plasma spots for therapeutic monitoring of amikacin: Validation of an UHPLC-MS/MS assay and pharmacokinetic application

•Amikacin and creatinine can be measured in clinically relevant concentrations in DPS using UHPLC-MS/MS.•Amikacin was stable in DPS for 2 days at room temperature.•Amikacin and creatinine concentrations in dried plasma spots and plasma are similar.•Pharmacokinetic estimations using dried plasma or plasma concentrations were essentially the same. Amikacin (AMI) is an aminoglycoside antibiotic widely used in the treatment of severe infections caused by multi-resistant bacteria, with established exposition targets in therapeutic drug monitoring (TDM). The usual specimen for AMI concentration measurement is plasma or serum. The access to TDM of AMI in Developing Countries is constrained by the limited availability of laboratories performing the quantitation of this drug. In this context, the use of dried microsamples, such as dried plasma spots (DPS) could be an alternative to allow reduced specimen transportation and storage costs in resource-limited settings, increasing the access to TDM of AMI. This study aimed to develop and validate the first report of simultaneous determination of AMI and creatinine (CRE) in DPS, using UHPLC-MS/MS. Precision, accuracy and stability assays showed acceptable results. AMI was stable in DPS for 14 days at 6 °C, 2 days at 22 °C, and one day at 42 °C. CRE was stable during 14 days at all tested temperatures. AMI and CRE concentrations in DPS and plasma were compared by Passing-Bablok regression and Bland and Altmann plots and presented comparable results. Estimates of patient’s clearance, volume of distribution and suggested doses of AMI were also similar using DPS or plasma concentrations. The assay provides a useful logistic alternative to allow more widespread access to dose individualization of AMI in limited resources settings.