Sex differences in diazepam protein binding in patients with renal insufficiency.

Sex differences in the extent of binding of diazepam to plasma protein were assessed in a series of patients with renal insufficiency previously described by Kangas et al. Among identifiable independent variables, sex alone accounted for the greatest proportion of variability in percent unbound diazepam (r = 0.33), whereas age and serum creatinine accounted for practically none. The mean (+/- SE) percent unbound among females (10.8 +/- 2.8%) was larger (p less than 0.1) than among males (5.8 +/- 1.3%). Since only the unbound fraction of diazepam in plasma is available for pharmacologic activity, the intensity and duration of diazepam's clinical action in patients with renal insufficiency might differ between males and females.