title: Betamethasone in pregnancy: influence of maternal body weight and multiple gestation on pharmacokinetics.
abstract: OBJECTIVE
  The goals of the study were to estimate the pharmacokinetic parameters of standard dose betamethasone in a large obstetrics population and evaluate the effect of maternal body size and multiple gestation on the pharmacokinetic parameters and their observed variability.
  
  
  METHODS
  This was a prospective pharmacokinetic study. Liquid chromatography mass spectrometry was used to measure betamethasone plasma concentrations. Pharmacokinetic parameters and significant clinical covariates were estimated with mixed effect modeling. Bootstrap analysis confirmed validity of the model.
  
  
  RESULTS
  Two hundred seventy-four blood samples from 77 patients were obtained. The greatest effect on pharmacokinetic variability was observed with maternal lean body weight (LBW). The relationship between the pharmacokinetic parameters and LBW remained linear over a wide range of maternal body sizes. Multiple gestations did not affect the pharmacokinetic parameters.
  
  
  CONCLUSIONS
  Individualization of betamethasone dosing by maternal LBW reduces variability in drug exposure. Mutiple gestations do not require betamethasone dosing adjustment, because pharmacokinetics are the same as singleton gestations.
authors.affiliation: Division of Maternal Fetal Medicine, Department of Obstetric and Gynecology, University of Illinois at Chicago, Chicago, IL, USA. 3micaela@gmail.com
authors.forename: Micaela
authors.initials: M
authors.lastname: Della Torre
authors.forename: Judith U
authors.initials: JU
authors.lastname: Hibbard
authors.forename: Hyunyoung
authors.initials: H
authors.lastname: Jeong
authors.forename: James H
authors.initials: JH
authors.lastname: Fischer
mesh_terms: D000293:Adolescent; D000328:Adult; D019540:Area Under Curve; D001499:Bayes Theorem; D001623:Betamethasone / Q000097:blood / Q000493:pharmacokinetics*; D015992:Body Mass Index; D001835:Body Weight; D002853:Chromatography, Liquid; D005260:Female; D005938:Glucocorticoids / Q000097:blood / Q000493:pharmacokinetics*; D006801:Humans; D008875:Middle Aged; D011247:Pregnancy; D011272:Pregnancy, Multiple; D011446:Prospective Studies; D053719:Tandem Mass Spectrometry
chemical_list: D005938:Glucocorticoids; D001623:Betamethasone
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