title: Therapeutic Drug Monitoring of Pentobarbital: Experience at an Academic Medical Center.
abstract: BACKGROUND
  Pentobarbital is used for management of intractable seizures and for reducing elevated intracranial pressure. Dosing of pentobarbital can be aided by therapeutic drug monitoring (TDM). There is no commercially available automated assay for measurement of pentobarbital serum/plasma concentrations; consequently, chromatography-based assays are often used.
  
  
  METHODS
  Pentobarbital TDM was studied over a 14-year period at an academic medical center. 154 patients (94 adult, 60 pediatric) were identified who had pentobarbital levels ordered at least once during a hospital encounter. Chart review included patient diagnosis, indication for pentobarbital therapy, recent or concomitant medication with other barbiturates, patient disposition, organ donation, pentobarbital dosing changes, and neurosurgical procedures. Pentobarbital serum/plasma concentrations were determined on an automated clinical chemistry platform with a laboratory-developed test adapted from a urine barbiturates immunoassay.
  
  
  RESULTS
  Chart review showed therapeutic use of pentobarbital generally consistent with previously published literature. The most common errors observed involved confusion in barbiturate names (eg, mix-up of pentobarbital and phenobarbital in test ordering or in provider notes) that seemed to have minimal impact on TDM effectiveness, with pentobarbital serum/plasma concentrations generally within target ranges. The laboratory-developed pentobarbital immunoassay showed cross-reactivity with phenobarbital and butalbital that was eliminated by alkaline and heat pretreatment. The immunoassay was linear to 20 mcg/mL and correlated closely with gas chromatography-mass spectrometry measurements at a reference laboratory.
  
  
  CONCLUSIONS
  Pentobarbital TDM can be performed by immunoassay on an automated clinical chemistry platform, providing an alternative to chromatography-based methods. Confusion in barbiturate names is common, especially pentobarbital and phenobarbital.
authors.affiliation: Department of Pathology, University of Iowa Hospitals and Clinics, Iowa City, Iowa.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Humble
authors.forename: Alexandra
authors.initials: A
authors.lastname: Ehlers
authors.forename: Brittany L
authors.initials: BL
authors.lastname: Pakalniskis
authors.forename: Cory
authors.initials: C
authors.lastname: Morris
authors.forename: Denny
authors.initials: D
authors.lastname: Drees
authors.forename: Jeff
authors.initials: J
authors.lastname: Kulhavy
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Krasowski
mesh_terms: D000046:Academic Medical Centers; D000328:Adult; D002648:Child; D002675:Child, Preschool; D016903:Drug Monitoring / Q000379:methods*; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D006801:Humans; D006993:Hypnotics and Sedatives / Q000493:pharmacokinetics*; D007118:Immunoassay / Q000379:methods; D007223:Infant; D008297:Male; D008875:Middle Aged; D010424:Pentobarbital / Q000493:pharmacokinetics*; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D006993:Hypnotics and Sedatives; D010424:Pentobarbital