Interaction of azithromycin and methylprednisolone with ex-vivo extracorporeal membrane oxygenation circuits (ECMO)

BackgroundAzithromycin and methylprednisolone are two medications that are commonly used in patients who require ECMO support. Unfortunately, ECMO support can decrease drug concentrations through adsorption to circuit components. Such interactions have not been well described for either azithromycin or methylprednisolone. This study determined the extraction of these medications by ECMO circuits in an <i>ex-vivo</i> system.MethodsMedications were administered to closed-loop, blood-primed ECMO circuits to attain target therapeutic concentrations. Drug concentration remaining in the circuit was measured over 6 h. The difference in medication recovery was compared between the ECMO circuits and controls using two-sample t-tests.ResultsConcentrations of azithromycin and methylprednisolone remained constant in control experiments over time, indicating medication stability in blood. There was no statistical difference in percent recovery after 6 h between control experiments and the ECMO circuits for either azithromycin (<i>p</i> = .32) or methylprednisolone (<i>p</i> = .17).DiscussionAzithromycin and methylprednisolone did not significantly interact with <i>ex-vivo</i> ECMO circuits. While these studies do not account for all <i>in-vivo</i> pharmacokinetic changes that may occur as a result of ECMO and critical illness, they suggest that standard dosing may be adequate to achieve therapeutic concentrations of azithromycin and methylprednisolone.