Modified Method for Measuring Potentiation of Barbiturate Anesthesia and its Relationship to Hypothermia

Abstract

Pretreatment of mice with a pheno-thiazine depressant drug potentiates the action of hexobarbital. Under these conditions doses of 40 mg/kg intraperitoneally or 25 mgAg intravenously of hexobarbital (which alone were not anesthetic) caused loss of righting reflex within 15 minutes. By using 3 doses of the phenothiazine and determining the percentage of mice which lost this reflex at each dose level, the ED50[plus or minus]SE for the potentiating activity of a. phenothiazine was calculated by log-probit methods. Use of this method showed that although a phenothiazine caused both hypothermia and potentiation of hexobarbital at the same dose levels, these pharmacologic properties are independent of each other.