In-vivo and in-vitro studies on the effect of Huang-Lian-Jie-Du-Tang on nimodipine transport across rat blood-brain barrier.

Huang-Lian-Jie-Du-Tang (HLJDT), an aqueous extract of Rhizoma Coptidis, Radix Scutellariae, Cortex Phellodendri and Fructus Gardeniae (3:2:2:3) is an important multi-herb remedy in traditional Chinese medicine (TCM). The aim of this study was to evaluate the effect of HLJDT on nimodipine transport across rat blood-brain barrier (BBB). It was found that in-vivo the brain concentrations of nimodipine significantly increased when rats were pretreated with HLJDT. In-vitro, the serum of HLJDT-treated rats increased the accumulation of nimodipine in primary cultured rat brain microvessel endothelial cells (rBMECs) and decreased the expression of P-glycoprotein (P-gp) on rBMECs. Our previous study showed that the peak concentration of baicalin and berberine in rats after administration of HLJDT was 5 mug mL(-1) and 10 ng mL(-1), respectively. This study showed that 5 mug mL(-1) baicalin significantly increased the accumulation of nimodipine in rBMECs, while 10 ng mL(-1) berberine had no effect on the accumulation of nimodipine in rBMECs. Both the in-vivo and in-vitro experimental findings indicated that HLJDT pretreatment may alter the transport of nimodipine across rat BBB.