An UPLC-MS/MS method to monitor Estriol injection and comparison of pharmacokinetic characteristics after irradiation

To develop an UPLC-MS/MS method for the accurate quantification of Estriol (E3), a new radioprotective agent, and observe the variation in pharmacokinetic characteristics of E3 after irradiation. As a hormone drug, the gender differences of E3 metabolism were also concerned here. Various chromatographic and mass spectrometric conditions of E3 were optimized. The specificity, linearity, precision and accuracy of UPLC-MS/MS method were validated. Twenty SD rats, half male and half female, were administered with intramuscular (im) injection of 2.7 ​mg/kg E3, and then divided randomly into two groups, sham-irradiated group (Con) and irradiated group (IR). IR group was irradiated to 7 ​Gy of γ-rays. Blood samples were collected at different times post-irradiation and E3 concentrations were detected. The changes of concentration-time variation and pharmacokinetic parameters for E3 after irradiation were investigated, together with metabolic differences between male and female rats. The range of the calibration curve of UPLC-MS/MS for E3 was 1.00–200.0 ​ng/mL. Con group reached maximum concentration (Cmax) (77.57 ​± ​18.71) ng/mL at (0.68 ​± ​0.29) h (Tmax) after im injection. The drug concentration-time profiles and pharmacokinetic parameters of E3 were consistent before and after irradiation. The areas under time curve (AUC0-t) of E3 were (353 ​± ​74) h·ng/mL for Con group, and (299 ​± ​74) h·ng/mL for IR group (P ​> ​0.05). There were also no statistical differences in pharmacokinetic parameters between female and male rats. The elimination half-lifes (T1/2) of males and females were (3.02 ​± ​0.68) h and (3.01 ​± ​0.42) h in Con group, and (3.64 ​± ​0.51) h and (3.38 ​± ​0.60) h in IR group, respectively (P ​> ​0.05). A rapid and sensitive UPLC-MS/MS method for determination of E3 was established. The pharmacokinetic characteristics of E3 in rat were not affected by 7 ​Gy irradiation and gender differences. This study provided a theoretical basis for the development and application of new radiation injury treatment drug. •A rapid and sensitive UPLC-MS/MS method was established for the determination of Estriol (E3), which is a new radioresistant drug.•The preclinical pharmacokinetics of E3 injection in vivo was explored and the metabolic half-life was 3-4 h in rat plasma after intramuscular administration.•After 7 ​Gy γ-ray irradiation, the tendency of drug concentration-time profiles and pharmacokinetic parameters of E3 in irradiated rats were consistent and