This is an open-label pharmacokinetics (PK) study. It aims to assess the PK parameters of metamizole and its metabolites following a single IV administration of metamizole (10mg/kg) in children less than 6 years of age.~Thirty-nine children, 3-72 months of age, undergoing elective surgery at the University of Basel Children's Hospital, will receive, on the day of surgical procedure, a single dose of metamizole 10 mg/kg. After this dose, blood and saliva samples will be obtained at predetermined post-dose time points to measure concentrations of metamizole and its metabolites. The maximal duration of subject participation will be 24 hours. Plasma PK parameters (AUC, Cmax, Tmax, t1/2) of each analyte will be derived using noncompartmental methods. A population PK approach will be applied to characterize inter-subject variability and quantify the potential influence of age, sex and body weight on the PK parameters.~There are no published pharmacokinetic studies of metamizole in pediatrics. Furthermore, although Swissmedic provides no dose information for IV administration in infants with a body weight of less than 9 kg, IV is the most frequently used route of administration for direct postoperative analgesia in pediatrics, including infants with body weights of less than 9 kg. Due to the absence of data and the lack of any dosing recommendation for infants with a body weight less than 9 kg, the IV administration of metamizole in infants is off-label and inconsistent across hospitals and prescribing paediatricians.
This study aims to assess the PK parameters of metamizole following a single IV administration of metamizole in children less than 6 years of age.