[Plasma concentration and amnesia following lormetazepam and flunitrazepam in i.v. premedication]

The correlation between serum levels and degree of amnesia following 0.03 mg/kg lormetazepam or 0.02 mg/kg flunitrazepam was analysed in a prospective randomised single-blind study evaluating 20 patients with ASA classification I in each group. Blood specimens were drawn and amnesia tests performed 20, 40 and 60 min. after drug administration. The plasma level of lormetazepam was 1.8 to 2.0 times higher than that of flunitrazepam; however, the difference of lormetazepam concentrations was considerably large between the investigated individuals. There was no difference in the degree of amnesia, but also no correlation with plasma levels was measured. A serum level breakpoint for the occurrence of amnesia could not be defined.