LACK OF PHARMACOKINETIC INTERACTION BETWEEN VINPOCETINE AND OXAZEPAM

The influence of multiple doses of vinpocetine (10 mg three times dail y) on the steady state plasma concentrations of oxazepam (10 mg three times daily) was studied in 16 healthy subjects. The mean (+/- s.d.) A UC (ng ml(-1) h(-1)) of oxazepam over 24 h during combined treatment w as 4716 +/- 2296 and for oxazepam treatment alone it was 4737 +/- 2448 (95% confidence intervals for ratio of means = 95.4-103.7%). The degr ee of plasma protein binding of oxazepam was 98.11 +/- 0.32% and was n ot affected by vinpocetine. Independent of vinpocetine treatment a sig nificant diurnal change in the plasma binding of oxazepam was observed ; the free drug fraction was 20% higher during the night than during t he day. C-max and AUC values based on total oxazepam in plasma were 10 % lower during the night. The results indicate a lack of influence of vinpocetine on oxazepam kinetics. Diurnal changes in the plasma bindin g of oxazepam probably have no clinical consequences.