The effects of berberine on the pharmacokinetics of cyclosporin A in healthy volunteers.

The effects of berberine (BBR) on the pharmacokinetics of ciclosporin A (CsA) were examined in healthy volunteers. Six healthy male volunteers were orally treated with 0.3 g BBR, twice daily for 10 days. Pharmacokinetic investigations on CsA at 6 mg/kg were done both before and at the end of the BBR treatment period. Another six healthy male volunteers were involved in the pharmacokinetic study with 3 mg CsA/kg, in which the subjects orally received the second single dose of 3 mg CsA/kg, followed by a single oral dose of 0.3 g BBR. The blood CsA concentrations were determined by fluorescence polarization immunoassay. In the pharmacokinetic study with 6 mg CsA/kg, BBR caused no significant changes in the pharmacokinetic parameters of CsA. However, in the trial with 3 mg CsA/kg, the average percentage increase in area under the blood concentration-time curve of CsA was 19.2% (P < 0.05) and the mean C12 increased to 123 microg/l from 104 microg/l (P < 0.05), without altering elimination half-life (t(1/2)), maximum blood drug concentration (Cmax), time to Cmax (tmax), apparent oral clearance (CL/F). The present results suggest that BBR can increase the oral bioavailability of CsA at the dosage of 3 mg/kg. The BBR-mediated increase in CsA bioavailability may be partly attributed to a decrease in liver and/or intestinal metabolism through the inhibition of CYP3A4 in the liver and/or gut wall. The BBR-induced increase in emptying time of stomach and small intestine might be another reason for the increase in CsA bioavailability. However, the speculation should be proved by further investigation. 2006 Prous Science.