A UPLC-MS/MS method for determination of cepharanthine in rat plasma and its pharmacokinetics

To establish and validate a sensitive and reliable ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for quantitative analysis of cepharanthine in rat plasma.

Plasma samples were treated using the protein precipitation method. Chromatographic separation was performed on column maintained at 50 ℃. Gradient elution was employed with mobile phases composed of (A) 0.05% formic acid aqueous solution containing 1 mmol/L ammonium formate and (B) 0.1% formic acid in acetonitrile at a flow rate of 0.40 mL/min. Mass spectrometric detection was carried out using an electrospray ionization (ESI) source in a positive-ion mode with multiple reaction monitoring (MRM). Mass transition m/z 607.3→576.2 was adopted for cepharanthine and m/z 260.2→ 116.1 for propranolol, the internal standard. This method was validated and used to quantify cepharanthine in plasma samples collected from rats following a single intragastric administration to investigate its pharmacokinetic profile.

Cepharanthine proved to be linear in rat plasma over the concentration range of 0.1 to 80 ng/mL. The intra-and inter-batch accuracies ranged from -0.43% to 11.73%, and precisions from 3.04% to 13.83%. The recovery rates of quality control samples ranged from 86.70% to 88.48%. The accuracy and precision met the standards across six lots of the matrix. The quality control samples remained stable under the following conditions: 24 hours of storage in the autosampler at 15 ℃, followed by three freeze-thaw cycles, and 10 days of storage at -20 ℃. All these met the requirements for bioanalytical analysis of samples. Pharmacokinetic studies showed that the time to maximum concentration (T_max) was 6 to 12 h, the maximum concentration (C_max) was (12.31±3.78) ng/mL, the terminal elimination half-life (t_1/2) was (10.07±0.66) h, and the mean residence time (MRT_0-t) was (24.80±1.98) h after intragastric administration of 3 mg/kg cepharanthine to rats.

This study has established a UPLC-MS/MS method for quantitative analysis of cepharanthine in the rat plasma matrix, which is simple and sensitive, with a lower limit of quantification of 0.1 ng/mL.