[Comparison of premedication regimes. A randomized, controlled trial]

The effect of two premedication regimes with different benzodiazepines on anxiety, hemodynamic data, sympatho-adrenal activity, and bispectral index (BIS) was evaluated during the variable time period prior to induction of anesthesia.

This prospective, double-blind study was performed with 50 ASA class I and II patients. Patients were randomized either to group I: evenings 22.00 hours 50 mg chlorazepate dipotassium (CD), mornings 07.00 hours 25 mg CD, placebo 30 min prior to anesthesia (on demand) or group II: evenings 50 mg CD, mornings placebo, 7.5 mg midazolam on demand.

In group I the BIS dropped after administration of 25 mg CD and was significantly lower at 08.00, 09.00 and 10.00 hours compared to baseline (mean+/-SD; 90+/-5, 87+/-7 and 87+/-7, respectively vs. 95+/-4; p<0.05), whereas the BIS of group II did not decrease significantly. Both groups did not differ significantly with respect to all variables obtained throughout the study period.

We conclude that 50 mg CD the evening before surgery prevented an increase of anxiety and sympatho-adrenal activity in both groups and might therefore be sufficient as premedication. Fixed time application of 25 mg CD at 07.00 hours or 7.5 mg midazolam 30 min prior to anesthesia did not further affect these variables preoperatively.