A Psychological and Physiological Evaluation of the Effects of Intravenous Diazepam

¹ Consultant Psychiatrist, Department of Psychiatry, St. George's Hospital Medical School, Atkinson Morley's Hospital, 31 Copse Hill, London SW20 0NE
² Psychologist, Department of Psychiatry, St. George's Hospital Medical School, Atkinson Morley's Hospital, 31 Copse Hill, London SW20 0NE
³ Registrar, Department of Psychiatry, St. George's Hospital Medical School, Atkinson Morley's Hospital, 31 Copse Hill, London SW20 0NE, Department of Physiology, University College London, Gower Street, London WC1

1. Intravenous diazepam (10 mg.) was slowly infused into 15 anxious patients over a ten-minute period, to determine the psychological and physiological effects of the drug. The infusion had been preceded by a similar placebo procedure in which only the solvent had been injected. It was found that on the Clyde Mood Scale the patients were statistically significantly less `Dizzy' (`sick to the stomach, dizzy, jittery, and shaky') and less `Unhappy'(`sad, down-hearted, troubled and worried') at the end of the experimental procedure. They were not significantly more `Friendly', or `Sleepy' or less `Aggressive' or `Clear-thinking'.

2. There had been a significant reduction in Observer and Self-Ratings of anxiety, and this was accompanied by a significant reduction in physiological arousal, as evidenced by a fall in forearm blood flow and heart rate by the end of the experiment. It is likely that these changes were due to the diazepam.

3. When the mean values of these measurements during `Diazepam' were compared with the `Placebo' period, it was found that the Observer (OR) and Self-Rating (SR) of anxiety were significantly less during the active medication, but the differences in forearm blood flow (FBF) and heart rate (HR) were not statistically significant. The maximal effect of the infusion on anxiety (OR and SR), and physiological arousal (FBF and HR), was seen during the period 20-30 minutes after the administration of diazepam ended.

4. A group of 5 normal controls were also studied and were found to be significantly less `Clear-thinking' after 5 mg. of diazepam.

5. Finger pulse amplitude increased after diazepam, indicating cutaneous vasodilatation. Blood pressure, respiration and sweat gland activity were not significantly affected.

6. Pain at the site of injection of i.v. diazepam, and a method of overcoming this, is discussed and the mode of action of the benzodiazepines on the limbic system is commented on.