title: Injectable sodium pentobarbital: Stability at room temperature.
abstract: BACKGROUND
  Sodium pentobarbital (Nembutal) is a barbiturate used in research as an anesthetic in many animal models. The injectable form of this drug has lately become difficult to procure and prohibitively expensive. Due to this lack of availability, researchers have begun to compound injectable sodium pentobarbital from so-called "nonpharmaceutical" pentobarbital. Some oversight agencies have objected to this practice, claiming a lack of quality control and degradation of the drug. We sought with this study to establish both: 1) a protocol for the preparation of injectable sodium pentobarbital, and 2) standard operating procedures to monitor the quality of the preparation and degradation of the drug over time.
  
  
  METHODS
  Our preparation consists of a mixture of sodium pentobarbital in alkaline aqueous solution, propylene glycol, and ethanol. Pentobarbital content in this preparation was assayed by high-pressure liquid chromatography (HPLC). We also assayed pentobarbital content over time in preparations of various ages up to 6 years old.
  
  
  RESULTS
  We determined that the drug degraded at a maximum of 0.5% per year in our preparation (alkaline water/propylene glycol/ethanol) when stored in the dark at room temperature. A yellow discoloration developed after about 2 years, which we have arbitrarily determined disqualifies the preparation from use as an anesthetic. Attempts to spectroscopically assay this discoloration were not successful.
  Pentobarbital sodium (CID: 14075609).
authors.affiliation: A. T. Still University of Health Sciences, Department of Physiology, Kirksville, MO 63501, United States.
authors.forename: Sydney M
authors.initials: SM
authors.lastname: Priest
authors.affiliation: A. T. Still University of Health Sciences, Department of Physiology, Kirksville, MO 63501, United States. Electronic address: tgeisbuhler@atsu.edu.
authors.forename: Timothy P
authors.initials: TP
authors.lastname: Geisbuhler
mesh_terms: D000759:Adjuvants, Anesthesia / Q000008:administration & dosage / Q000737:chemistry / Q000592:standards; D000818:Animals; D002626:Chemistry, Pharmaceutical; D002851:Chromatography, High Pressure Liquid; D004339:Drug Compounding / Q000379:methods / Q000592:standards; D004355:Drug Stability; D004356:Drug Storage; D007267:Injections; D010424:Pentobarbital / Q000008:administration & dosage / Q000737:chemistry / Q000592:standards; D013056:Spectrophotometry, Ultraviolet; D013997:Time Factors
chemical_list: D000759:Adjuvants, Anesthesia; D010424:Pentobarbital
keywords: High-pressure liquid chromatography; Nembutal; Pentobarbital; Stability