An objective evaluation of tranquillizers as preanaesthetic medication: effect on adrenocortical function

Abstract

The present study was undertaken to evaluate the tranquillizers objectively as premedicating drugs. The sedative effects of placebo, hydroxyzine (2.5 mg/kg), diazepam (0.2 mg/kg) and nitrazepam (0.2 mg/kg) were judged both subjectively by the double-blind method and objectively by measurement of free Cortisol levels in the plasma of 54 patients. These agents were administered by mouth at 8.00 pm on the day before operation and at 7:00 am on the day of operation just after the first blood sampling. In order to avoid the diurnal variation in the plasma Cortisol level, the plasma levels of the same patients at 7:00, 7:30, 8:00, and 8:30 am on the previous day served as controls to the values at corresponding times on the operative day. While placebo had no measurable effects, diazepam and nitrazepam clearly decreased plasma free Cortisol levels at 8:30 am and hydroxyzine significantly reduced the value at 8:00 am. The sedative effects of these tranquillizing agents and the ineffectiveness of the placebo definitely correlated with the alterations in plasma Cortisol levels. The clinical application of these findings was also discussed. © 1969 Canadian Anesthesiologists.