Coffee consumption, cigarette smoking and reporting of drowsiness in anxious patients treated with benzodiazepines or placebo.

Data obtained from anxious outpatients treated with either chlordiazepoxide or diazepam (n = 533) or placebo (n = 285) were used to explore the impact of coffee/tea and cigarette consumption upon the frequency of reporting of drowsiness after 2 weeks of treatment. Strong evidence was provided that both cigarette smoking and coffee drinking affect the frequency with which drowsiness is reported by patients receiving the two benzodiazepines. However, not only the magnitude but also the direction of the impact of coffee consumption upon drowsiness depends upon the level of cigarette smoking and vice versa. For patients smoking less than or equal to 1 pack of cigarettes/day, drowsiness is reported less frequently by heavy coffee users while for patients smoking greater than 1 pack of cigarettes/day, drowsiness is reported more frequently by heavy coffee users. Similarly, for patients drinking less than or equal to 2 cups of coffee/day, drowsiness occurs less frequently among heavier smokers while for patients drinking greater than 2 cups of coffee/day, drowsiness occurs more frequently among heavier smokers. These results are consistent with reports that particular substances contained in coffee and tea and in cigarette smoke stimulate the synthesis of hepatic enzymes which metabolize both the benzodiazepines here studied and the substances which have stimulated enzyme synthesis.