Trace level quantification of deuterated 17beta-estradiol and estrone in ovariectomized mouse plasma and brain using liquid chromatography/tandem mass spectrometry following dansylation reaction.
A sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) method coupled with dansylation was developed for the simultaneous quantification of exogenously administered deuterated 17beta-estradiol-d4 (E2-d4) and its metabolite, estrone-d4 (E1-d4), in mouse plasma and brain homogenates. The dansylation reaction was simple, fast, and sensitive, and a lower limit of quantification of 50 pg/mL was achieved by using 50 microL of mouse plasma. Interference from endogenous 17beta-estradiol and estrone in plasma and brain samples was minimized by the use of deuterated-E2 as well by utilizing ovariectomized (OVX) mice. The recovery of dansylated derivative exceeded 83% and the reaction was completed within approximately 3 min. The intra- and inter-day assay precision were better than 12.9% and assay accuracy ranged between 92-104% for E1-d4 and E2-d4 in plasma, respectively. The absorption of E2-d4 at both 1 and 3 mg/kg P.O. was rapid, reaching peak plasma concentrations (Cmax) at 5 min post-dose that was the earliest time point obtained, and were 1.1 and 13.8 ng/mL, respectively; the Cmax values for the estrone metabolite, E1-d4, were 1.1 and 43.2 ng/mL, respectively. The area-under-the-plasma-time curve (AUC(0-2 h)) values were determined to be 0.65 and 2.90 ng. h/mL for E2-d4 and 0.77 and 6.74 ng. h/mL for E1-d4, respectively, at 1 and 3 mg/kg. The mean brain-to-plasma ratio for E1-d4 and E2-d4 after P.O. administration of E2-d4 to the OVX mice at 1 and 3 mg/kg indicated that both E1-d4 and E2-d4 were present in the brain as well as in the circulation.
Department of Drug Metabolism, Merck Research Laboratories, Rahway, NJ 07065, USA. yuanquing_xia@merck.com
Yuan-Qing
YQ
Xia
Steve W
SW
Chang
Shefali
S
Patel
Ray
R
Bakhtiar
Bindhu
B
Karanam
David C
DC
Evans
D000818:Animals; D001921:Brain / Q000378:metabolism*; D001923:Brain Chemistry; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003619:Dansyl Compounds / Q000737:chemistry; D003903:Deuterium; D004958:Estradiol / Q000097:blood* / Q000737:chemistry / Q000493:pharmacokinetics; D004970:Estrone / Q000097:blood*; D051379:Mice; D010052:Ovariectomy; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
D003619:Dansyl Compounds; D004970:Estrone; D004958:Estradiol; D003903:Deuterium