Application of 1-alkylamines to a liquid chromatographic/turbo ionspray tandem mass spectrometric method for quantifying metabolites of a new bone anabolic agent, TAK-778, in human serum.
We investigated the application of alkylamines, as additives to the mobile phase, to a quantification method for the metabolites, M-III and M-IV, of TAK-778, which is a new bone anabolic agent, in human serum using liquid chromatography/tandem mass spectrometry (LC/MS/MS). Prior to setting up the analytical method, we found that 1-alkylamines co-existing with M-III and M-IV in the turbo ionsprayed solution formed 1-alkylammonium adduct molecules of these metabolites during the ionization process, and the abundance of the adduct ions was considerably higher than that of protonated molecules ([M + H](+)s) of these metabolites. Based on these findings, we investigated a variety of 1-alkylamines and their spiked concentrations in the mobile phase for LC/MS/MS analysis to obtain higher sensitivities for the quantification of these metabolites. After these examinations, we found that 1-hexylamine at a final concentration of 0.05 mmol l(-1) was the most suitable additive for the mobile phase, and set the selected reaction monitoring (SRM) ions for the 1-hexylammonium adduct molecule and [M + H](+), allowing about a fivefold gain in the SRM chromatographic peak compared with that without 1-hexylamine. The adduct ion was considered to be formed by interaction between the amino group of 1-hexylamine and the phosphoryl group of M-III and M-IV. The internal standard (I.S.) used was deuterated M-III for each metabolite. The analytes and I.S. were extracted with diethyl ether from serum samples at neutral pH and injected into the LC/MS/MS system with a turbo ionspray interface. The limit of quantification for both analytes was 0.5 ng ml(-1) when 0.1 ml of serum was used, and the calibration curves were linear in the range 0.5-100 ng ml(-1). The method was precise; the intra- and inter-day precisions of the method were not more than 5.6%. The accuracy of the method was good, with deviations between added and calculated concentrations of M-III and M-IV being typically within 16.6%. This method provided reliable pharmacokinetic data for M-III and M-IV after the intramuscular administration of TAK-778 sustained-release formulation in humans.
Drug Analysis and Pharmacokinetics Research Laboratories, Pharmaceutical Research Division, Takeda Chemical Industries Ltd., 2-17-85 Juso-Honmachi, Yodogawa-ku, Osaka 532-8686, Japan. teshima_kouichirou@takeda.co.jp
Koichiro
K
Teshima
Takahiro
T
Kondo
Chie
C
Maeda
Tsuneo
T
Oda
Toshiaki
T
Hagimoto
Ryoichi
R
Tsukuda
Yoshinobu
Y
Yoshimura
D000478:Alkylation; D000588:Amines / Q000737:chemistry*; D001582:Benzothiepins / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D001711:Biotransformation; D001774:Blood Chemical Analysis / Q000295:instrumentation / Q000379:methods; D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007273:Injections, Intramuscular; D013058:Mass Spectrometry / Q000379:methods*; D012015:Reference Standards; D012680:Sensitivity and Specificity
D000588:Amines; D001582:Benzothiepins; C120450:TAK 778