Population Pharmacokinetics of Levosimendan and its Metabolites in Critically Ill Neonates and Children Supported or Not by Extracorporeal Membrane Oxygenation.

backgroundLevosimendan (LVSMD) is a calcium-sensitizer inotropic and vasodilator agent whose use might have a beneficial effect on the weaning of venoarterial extracorporeal membrane oxygenation (VA-ECMO). In light of LVSMD pharmacological characteristics, we hypothesized that ECMO may induce major pharmacokinetic (PK) modifications for LVSMD and its metabolites.

objectiveThe aim of this study was to investigate the PK of LVSMD and its metabolites, and to assess the effects of ECMO on PK parameters.

methodsWe conducted a multicentric, prospective study (NCT03681379). Twenty-seven infusions of LVSMD were performed, allowing for the collection of 255 blood samples. Non-linear mixed-effects modeling software (MONOLIX®) was used to develop a parent-metabolite PK model of LVSMD and its metabolites.

resultsMost patients received a 0.2 µg/kg/min infusion of LVSMD over 24 h. After elimination of non-reliable samples or concentrations below the limit of quantification, 166, 101 and 85 samples were considered for LVSMD, OR-1855 and OR-1896, respectively, of which 81, 53 and 41, respectively, were drawn under ECMO conditions. Parent-metabolite PK modeling revealed that a two-compartment model with first-order elimination best described LVSMD PK. Use of a transit compartment allowed for an explanation of the delayed appearance of circulating OR-1855 and OR-1896, with the latter following a first-order elimination. Patient weight influenced the central volume of distribution and elimination of LVSMD. ECMO support increased the elimination rate of LVSMD by 78%, and ECMO also slowed down the metabolite formation rate by 85% for OR-1855, which in turn is converted to the active metabolite OR-1896, 14% slower than without ECMO. Simulated data revealed that standard dosing may not be appropriate for patients under ECMO, with a decrease in the steady-state concentration of LVSMD and lower exposure to the active metabolite OR-1896.

conclusionsECMO altered PK parameters for LVSMD and its metabolites. An infusion of LVSMD over 48 h, instead of 24 h, with a slightly higher dose may promote synthesis of the active metabolite OR-1896, which is responsible for the long-term efficacy of LVSMD. Further trials evaluating ECMO effects using a PK/pharmacodynamic approach may be of interest. REGISTRATION: ClinicalTrials.gov identifier number NCT03681379.