Hypnotic effect of chlormethiazole in geriatric patients during long-term treatment

The hypnotic effect of chlormethiazole was studied for 3 months in 20 geriatric in-patients. Registered variables were the percentage of patients asleep at 10 pm and 6 am and the observed number of awakenings. Mental and somatic variables were rated according to the Crichton Geriatric Behavioural Rating Scale. Observations were made every second week. In 11 of the patients the plasma concentration of chlormethiazole was measured at regular intervals. No systematic significant change with time was observed for the percentage of patients asleep at 10 pm or for the number of awakenings. A significant decrease occurred in the percentage of patients asleep at 6 am. The long-term treatment with chlormethiazole did not cause any deterioration in the patients' behaviour, according to the geriatric rating scheme. Observed peak plasma levels of chlormethiazole did not change significantly during the study. Great interindividual variations in the plasma concentrations were observed. The results indicate that chlormethiazole is lastingly effective as a hypnotic agent in geriatric patients.