Comparison of Sedative Effects between Alprazolam and Diazepam in Healthy Subjects

This study was designed to compare the sedative effects of alprazolam and diazepam in healthy subjects using the choice reaction time test (CRTT) and the visual analogue self-rating scales. The subjects were 22 male volunteers, 19 to 23 yr old. Eleven subjects had high neuroticism (HN) levels determined by Maudsley Personality Inventory, and 11 had lower neuroticism (LN) levels. Subjects took a single 0.8 mg dose of alprazolam or a single 5 mg dose of diazepam in a-cross-over design using a double-blind method. Subjects were allowed to practice the CRTT to reach a plateau level of learning curve before entering the experimental sessions. The absorption rate of alprazolam was suggested to be delayed by food intake. The 0.8 mg alprazolam produced almost equivalent sedative effects to 5 mg diazepam in the CRTT performance of HN subjects. Alprazolam produced relatively marked subjective sedative effects such as "drowsiness" and "mentally slow" in LN subjects as compared to diazepam. With both drugs, the subjective sedative' effects and the decrease in blood pressure and pulse rate were found in LN subjects.