Effect of cyclosporine A on the pharmacokinetics of ginkgolide B in rats

The paper is aimed to investigate the effect of cyclosporine A (CyA) on the pharmacokinetics of ginkgolide B (GB) in rats, and to look for the mechanism of the changes in pharmacokinetic behaviors of GB.  GB concentration in plasma, brain homogenate and urine samples of rats was determined by LC-MS.  Effects of CyA on plasma levels, brain distributions as well as urinary excretions after intravenous administration of GB were evaluated.  CyA coadministrated intravenously at 10 mg·kg⁻¹ or 20 mg·kg⁻¹ significantly increased AUC_{0−360 min} (P < 0.01) and decreased total CL of GB in rats.  While coadministrated CYP3A inhibitor     itraconazole (ICZ) has no appreciable effect on the pharmacokinetic behavior of GB.  CyA increased the brain uptake of GB in a dose-dependent manner.  The brain distribution of GB was significantly increased at 5 min by different doses of CyA (P < 0.001), while at 20 and 60 min only high dose of CyA could significantly increase the levels of GB in the brain (P < 0.01 and P < 0.001).  Different P-gp inhibitors CyA or verapamil (VER) or digoxin (DGX) decreased the urinary GB excretion, the urinary excretion of GB in 0−8 h were about 34.8% (P < 0.001), 59.4% (P < 0.001) and 79.7% (P < 0.05) of the control, separately.  No appreciable effect of ICZ was   observed on urinary excretion of GB.  Coadministration of P-gp inhibitors CyA could significantly increase the plasma level, accelerate the brain distribution and decrease the urinary excretion of GB.