title: Population pharmacokinetics of phenobarbital in infants with neonatal encephalopathy treated with therapeutic hypothermia.
abstract: OBJECTIVE
  Phenobarbital is the first-line treatment for neonatal seizures. Many neonates with hypoxic ischemic encephalopathy are treated with therapeutic hypothermia, and about 40% have clinical seizures. Little is known about the pharmacokinetics of phenobarbital in infants with hypoxic ischemic encephalopathy who undergo therapeutic hypothermia. The objective of this study was to determine the effect of therapeutic hypothermia on phenobarbital pharmacokinetics, taking into account maturational changes.
  
  
  METHODS
  Level 3 neonatal ICU.
  
  
  METHODS
  Infants with hypoxic ischemic encephalopathy and suspected seizures, all treated with phenobarbital. Some of these infants also received treatment with therapeutic hypothermia.
  
  
  METHODS
  None.
  
  
  METHODS
  A retrospective cohort study of 39 infants with hypoxic ischemic encephalopathy treated with phenobarbital (20 were treated with therapeutic hypothermia and 19 were not).
  
  
  RESULTS
  Data on phenobarbital plasma concentrations were collected in 39 subjects with hypoxic ischemic encephalopathy with or without therapeutic hypothermia. Using nonlinear mixed-effects modeling, population pharmacokinetics of phenobarbital were developed with a total of 164 plasma concentrations. A one-compartment model best described the pharmacokinetics. The clearance of phenobarbital was linearly related to body weight and matured with increasing age with a maturation half-life of 22.1 days. Therapeutic hypothermia did not influence the pharmacokinetic parameters of phenobarbital.
  
  
  CONCLUSIONS
  Therapeutic hypothermia does not influence the clearance of phenobarbital after accounting for weight and age. Standard phenobarbital dosing is appropriate for the initial treatment of seizures in neonates with hypoxic ischemic encephalopathy treated with therapeutic hypothermia.
authors.affiliation: Department of Pediatrics, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Renée A
authors.initials: RA
authors.lastname: Shellhaas
authors.forename: Chee M
authors.initials: CM
authors.lastname: Ng
authors.forename: Christina H
authors.initials: CH
authors.lastname: Dillon
authors.forename: John D E
authors.initials: JD
authors.lastname: Barks
authors.forename: Varsha
authors.initials: V
authors.lastname: Bhatt-Mehta
mesh_terms: D000367:Age Factors; D000927:Anticonvulsants / Q000493:pharmacokinetics* / Q000627:therapeutic use; D001831:Body Temperature; D001835:Body Weight; D005260:Female; D006801:Humans; D007036:Hypothermia, Induced; D020925:Hypoxia-Ischemia, Brain / Q000150:complications / Q000628:therapy*; D007231:Infant, Newborn; D008297:Male; D010634:Phenobarbital / Q000493:pharmacokinetics* / Q000627:therapeutic use; D012189:Retrospective Studies; D012640:Seizures / Q000150:complications / Q000188:drug therapy
chemical_list: D000927:Anticonvulsants; D010634:Phenobarbital