Is preloading with amikacin a measure able to mitigate sequestration? A preliminary in vitro study

Amikacin is sequestered in polyacrylonitrile filters. Methods mitigating sequestration are unknown. Amikacin elimination in a polyacrylonitrile-derived filter preloaded with amikacin was studied in a preliminary study. Amikacin concentrations were determined using an immunochemical method. Prismaflex™, Baxter-Gambro, and the ST™150 filter were used. Sessions were performed in a continuous diafiltration mode. Diafiltration flow rate was set to 2500 mL/h and filtration to 500 mL/h pre- and 1000 mL/h post-dilution. Net loss was set to zero. In sessions with preload, a 150 mg dose of amikacin was injected in the first 1 L bag of physiological saline when starting the priming. NeckEpur method was used for pharmacokinetic calculations. In the central compartment (CC), the mean initial concentration in the sessions without and with preload was 81.8 ± 6.0 mg/L. There were no significant differences in the AUC and AUC without or with preload. The preloading dose induced a significant increase in the AUC . Compared with sessions without preload, the clearance from the CC in sessions with preload decreased from 4.94 ± 0.43 to 3.75 ± 0.32 L/h, respectively. The elimination rates by diafiltration and sequestration in the sessions without and with preload were 82.3 ± 6.2/17.8 ± 6.2% and 125 ± 9.2%/0 ± 0%, respectively. The 150 mg loading dose was eliminated by diafiltration (42.5%) and by sequestration (57.5%). Preloading filter with amikacin modifies the disposition of amikacin by preventing further sequestration. Studies are needed to define an efficient preloading dosage regimen in actual condition of use.