小型猪血浆中二丙酸倍他米松及其代谢物倍他米松的LC-MS/MS同时测定方法的建立及在药动学研究中的应用

目的：建立同时测定小型猪血浆中二丙酸倍他米松及其代谢物倍他米松的LC-MS/MS法,并研究小型猪皮肤外用二丙酸倍他米松乳膏后,二丙酸倍他米松及倍他米松的药动学特征。方法：血浆样品经酸化后以乙醚-环己烷（4∶1）提取,LC-MS/MS分析,以Hedera ODS-2（150 mm×2.1 mm,5μm）为分析柱,流动相为5 mmol·L-1醋酸铵水溶液（含0.1%乙酸）–甲醇,梯度洗脱。二丙酸倍他米松、倍他米松及内标布地奈德的监测离子对分别为m/z 563.2（M＋CH3COO]-）→483.1、m/z 451.2（M＋CH3COO]-）→361.0和m/z 489.3（M＋CH3COO]-）→357.1。对小型猪外用二丙酸倍他米松乳膏后其血浆中二丙酸倍他米松及代谢物倍他米松的浓度进行测定,并计算主要药动学参数。结果：二丙酸倍他米松血药浓度在26.85~644.4 ng·L-1范围内线性关系良好,倍他米松血药浓度在10.62~637.2 ng·L-1范围内线性关系良好。结论：本方法专属性强、简便、灵敏,可用于血浆样本中二丙酸倍他米松及其代谢物倍他米松的测定及药动学研究。

Simuitaneous Determination of Betamethasone Dipropionate and Its Active Metabolite Betamethasone in Miniature Pig Plasma by LC-MS/MS and Its Application in Pharmacokinetic Study

Objective： To establish a liquid chromatography-tandem mass spectrometry（LC-MS/MS） method for the simultaneous determination of betamethasone dipropionate and its active metabolite betamethasone in miniature pig plasma and to investigate their pharmacokinetics after transdermal administration with betamethasone dipropionate cream in miniature pigs. Methods： After acidifi cated with acetic acid, the plasma sample was extracted with ethyl ether-cyclohexane（4：1） and then analyzed by LC-MS/MS. Chromatographic separation was performed on an Hedera ODS-2（150 mm×2.1 mm,5 μm） column with a gradient elution system of 5 mmol·L-1 ammonium acetate buffer containing 0.1% acetic acid- methanol. An atmospheric pressure chemical ionization source was applied and performed in negative ion mode. The ion transitions recorded in multiple reaction monitoring mode were m/z 563.2（M＋CH3COO]-）→483.1 for betamethasone dipropionate, m/z 451.2（M＋CH3COO]-）→361.0 for betamethasone and m/z 489.3（M＋CH3COO]-）→357.1 for the internal standard, respectively. Results： The calibration curves were linear over the range of 26.85-644.4 ng·L-1 for betamethasone dipropionate and 10.62-637.2 ng·L-1 for betamethasone, respectively. Conclusion： The developed method is specifi c, simple and sensitive. It can be applied to the determination of betamethasone dipropionate and its metabolite in plasma samples and the related pharmacokinetics study.