抄録
The concentration of diazepam in plasma and mixed saliva of normal human subjects was determined by gas-liquid chromatography/electron capture analysis after receiving a single venous or oral dose of diazepam (5 mg). The binding of diazepam to plasma protein in these subjects was determined using equilibrium dialysis or ultrafiltration method. A correlation of 0.720(p<0.01) was observed between salivary and plasma diazepam. Mean salivary diazepam was 2.4%(±0.2%) of the plasma diazepam. Mean free fraction of diazepam in plasma was 1.4% (±0.1%) by equilibrium dialysis or 1.5% (±0.2%) by ultrafiltration. Free diazepam concentration in plasma was better correlated to diazepam-induced subjective sedative effects such as "drowsiness", "feeble", "clumsy", and "mentally slow", than total diazepam concentration in plasma. The similar finding was also found in diazepam-induced subjective antianxiety effect such as "relaxed". The results suggest that the measurement of free diazepam concentration in plasma is of value in psychopharmacological studies. However, salivary diazepam concentration do not predict accurately the plasma total or unbound drug concentrations in an individual.
