The effect of chlorpromazine and reserpine on sedation and convulsive thresholds in schizophrenic patients

Abstract 1. 1. The effects of chlorpromazine and reserpine, in normal clinical doses, on both sedation and convulsive thresholds have been studied in a group of eleven chronic catatonic, schizophrenic patients. 2. 2. The sedation threshold was determined by injecting sodium amytal intravenously, the method being based on that of Shagass (1955). Because of the inaccessibility of the patients, a clinical threshold of sleep was used. The method of assessing the EEG threshold was modified in many cases as the original method did not give clear results. 3. 3. The convulsive threshold was determined by injecting hexazol intravenously, the method being based on that of Ulett et al. (1954). It was found necessary to modify the method as the end-point was reached after too few injections and the drug appeared to have a delayed effect, resulting in convulsions after the test was finished. 4. 4. The thresholds were determined in the normal and after pre-medication with: ( a ) chlorpromazine and ( b ) reserpine. Following reserpine, in normal clinical doses, neither the sedation threshold, nor the convulsive threshold showed any significant change. The same was true of the convulsive threshold after pre-treatment with chlorpromazine. 5. 5. After chlorpromazine there were significant changes in the sedation thresholds in a number of patients. These changes were consistent, being a lowering of the sedation threshold. The relation of these findings to the possible mode of action of the drugs and the reports of the occurrence of spontaneous seizures when they are used, is discussed.