Pharmacokinetic evaluation of new drugs during the last 20 years presents results of clinical trials performed with males or both sex samples without sex-related description and analysis. The aim of this trial was to investigate the sex-related pharmacokinetic differences of benzodiazepina (lorazepam) in healthy subjects of both sexes. A single oral dose of lorazepam 2 mg was administred 7 males (M) and 8 females (F). Blood samples to assess lorazepam plasma concentration by HPLC were obtained before and at different times following drug intake. Kinetic parameters were calculated for each subject. Peak levels (C_MAX) were 19,66 ng/mL (M= 16,28 ±2,51 ng/mL, F= 23.04 ±6.12 ng/mL). The time to reach maximum concentration (t_MAX) was between 1h (n= 7; M= 3, F= 4) and 1,5 hs (n= 4; M= 2, F=2). The biological elimination half-life (t_1/2) was 11,33 hs (M= 11.98 ±2.39 hs, F= 10.68 ±2,69 hs) and the Area Under the concentration-time Curve 0 to 48 hs (AUC_0-48) reached a maximum of 199,46 ng/mL·h (M= 168,36 ±28,09 ng/mL·h, F= 230,57 ±100,38 ng/mL·h). At +1h females showed higher values than males, significant differences in lorazepam levels were observed only at +1.5hs (M= 14,69 ng/mL, F= 19,18 ng/mL, p= 0,033) but no significant differences was obtained when comparing pharmacokinetic parameters by sex. Lorazepam was well tolerated by all subjects. In conclusions, the analysis of pharmacokinetic parameters by sex with lorazepam showed as light variation, new trials with larger samples must be made to determine whether or not the pharmacokinetic profile is sex-dependent. The perfomance of clinical trials to evaluate sex-related differences is very important to help optimize clinical use and drug prescription.

lorazepam; pharmacokinetics; sex-related differences; healthy subjects