Determination of cepharanthine in rat plasma by LC-MS/MS and its application to a pharmacokinetic study

Cepharanthine (CPA) has been reported to possess a wide range of pharmacological activities.

This study investigates the pharmacokinetic characteristics after oral or intravenous administration of CPA by using a sensitive and rapid LC-MS/MS method.

A sensitive and rapid LC-MS/MS method was developed for the determination of CPA in Sprague-Dawley rat plasma. Twelve rats were equally randomized into two groups, including the intravenous group (1 mg/kg) and the oral group (10 mg/kg). Blood samples (250 μL) were collected at designated time points and determined using this method. The pharmacokinetic parameters were calculated.

The calibration curve was linear within the range of 0.1-200 ng/mL (r = 0.999) with the lower limit of quantification at 0.1 ng/mL. After 1 mg/kg intravenous injection, the concentration of CPA reached a maximum of 153.17 ± 16.18 ng/mL and the t_1/2 was 6.76 ± 1.21 h. After oral administration of 10 mg/kg of CPA, CPA was not readily absorbed and reached C_max 46.89 ± 5.25 ng/mL at approximately 2.67 h. The t_1/2 was 11.02 ± 1.32 h. The absolute bioavailability of CPA by oral route was 5.65 ± 0.35%, and the bioavailability was poor.

The results indicate that the bioavailability of CPA was poor in rats, and further research should be conducted to investigate the reason for its poor bioavailability and address this problem.