HPLC-MS/MS method for determination of betamethasone in human plasma with application to a dichorionic twin pregnancy pharmacokinetic and placental transfers studies

Abstract Betamethasone (BET) is a synthetic glucocorticoid recommended for pregnant women at imminent risk of preterm birth before 34 weeks to reduce neonatal complications. There are different techniques to describe BET plasma quantification. However, none quantified the plasmatic concentration of BET in dichorionic (DC) twin pregnancies using LC-MS. Our objectives were to develop and validate a method for quantifying BET by LC-MS for pharmacokinetic (PK) and placental transfer studies in DC twin pregnancies. Blood samples were collected after intramuscular administration of a single BET dose containing 6 mg disodium phosphate + 6 mg acetate. BET was determined in plasma by liquid-liquid extraction. The method showed linearity in the range of 2-250 ng/mL, as well as precision and accuracy with a coefficient of variation and relative standard errors ≤ 15%. Additionally, the method presented selectivity and did not present matrix or carry-over effect. Stability tests also presented coefficient of variation and relative standard errors ≤ 15%. This is the first study which describe maternal and fetal plasma concentrations of BET in a DC twin pregnancy. The BET PK parameters were AUC0-∞, CL/F, Vd/F, Cmax, Tmax of 292.20 h*ng/mL, 39.08 L/h, 278.72 L, 25.55 ng/mL and 0.58 h, respectively. The placental transfer ratios of umbilical vein/maternal vein and intervillous space/maternal vein were 0.14 and 0.19 and 0.40 and 0.27 for both twins, respectively. However, a clinical study with more subjects is imperative to confirm this higher concentration of BET in the intervillous space.

摘要：倍他米松（Betamethasone，BET）是一种合成糖皮质激素，被推荐用于34周前存在早产风险的孕妇，以降低新生儿并发症的发生风险。目前已有多种用于定量检测BET血浆浓度的技术，但尚无采用液相色谱-质谱联用法（LC-MS）针对双绒毛膜（dichorionic，DC）双胎妊娠孕妇体内BET血浆浓度开展定量检测的相关研究。本研究旨在开发并验证一种采用LC-MS定量检测BET的方法，以用于双绒毛膜双胎妊娠的药代动力学（pharmacokinetic，PK）研究及胎盘转运研究。受试者单次肌肉注射含6mg磷酸倍他米松二钠与6mg醋酸倍他米松的BET制剂后采集血样，采用液液萃取法对血浆中的BET进行定量分析。该方法在2~250 ng/mL范围内呈现良好线性，其精密度与准确度的变异系数及相对标准误差均≤15%。此外，该方法具有良好的选择性，未观察到基质效应与交叉残留效应。稳定性试验结果显示，其变异系数及相对标准误差同样≤15%。本研究为首次报道双绒毛膜双胎妊娠孕妇及胎儿体内BET血浆浓度的研究。受试者的BET药代动力学参数分别为：AUC₀-∞为292.20 h·ng/mL、CL/F为39.08 L/h、Vd/F为278.72 L、Cmax为25.55 ng/mL、Tmax为0.58 h。两名胎儿的脐静脉/母静脉胎盘转运比以及绒毛间隙/母静脉胎盘转运比分别为0.14、0.19与0.40、0.27。不过，仍需开展更大样本量的临床研究以验证绒毛间隙中BET浓度更高这一结论。