Adult age and ex vivo protein binding of lorazepam, oxazepam and temazepam in healthy subjects.

To see if adult age correlates with ex vivo protein binding of lorazepam, oxazepam and temazepam in healthy subjects. Sixty healthy drug free subjects were recruited in the age groups 18-39, 40-64 and ≥65 years. Plasma albumin concentrations were determined. Ex vivo unbound fractions (f(u)) were assessed by spiking samples and measuring the free and total concentrations. No correlation of age with f(u) was seen. The study was powered to demonstrate a change in f(u) of ≥7-10%. A decline in plasma albumin concentration of ~0.03 g l(-1) year(-1) was seen with increasing age (P= 0.032) and was associated with increased f(u) of lorazepam (P= 0.009) and oxazepam (P= 0.014). There was no association of adult age with ex vivo f(u) of lorazepam, oxazepam or temazepam in healthy subjects.