Different effects of (+)­borneol and (­)­borneol on the pharmacokinetics of osthole in rats following oral administration.

ABSTRACT

Osthole is the primary active component of a number of herbal plants such as the Cnidium monnieri fruit. In traditional Chinese herb medicine, osthole is commonly used in combination with borneol to obtain improved pharmacological effects. The aim of the present study was to investigate the effect of borneol enantiomers on the pharmacokinetics of osthole. An appropriate high­performance liquid chromatography (HPLC) method was applied to determine the concentrations of osthole in plasma. Following oral administration of osthole alone or combined with borneol in rats, blood samples were collected and analyzed by HPLC. The results demonstrated that there were statistically significant differences in the pharmacokinetic parameters of osthole between osthole administration alone and co­administration with borneol. When combined with synthetic borneol, the AUC0­t, AUC0­∞ and Cmax of osthole increased by 48.153, 104.708 and 92.630%, respectively, while the CL/F decreased by 51.251%. When combined with (+)­borneol, the AUC0­t, AUC0­∞ and Cmax of osthole were increased by 61.561, 78.167, and 51.769%, respectively, while the CL/F decreased by 44.174% (P<0.01). In addition, when combined with (­)­borneol, the AUC0­t, AUC0­∞ and Cmax of osthole increased by 115.856, 167.786 and 271.289%, respectively, while the CL/F decreased by 60.686% (P<0.01). These results indicated that borneol may enhance gastrointestinal absorption and inhibit the metabolism of osthole. In addition, the promotional effect of (­)­borneol on the pharmacokinetic parameters of osthole was greater than that of (+)­borneol.