Respiratory benefit in preterm lambs is progressively lost when the concentration of fetal plasma betamethasone is titrated below two nanograms per milliliter
Erin L. Fee, Tsukasa Takahashi, Yuki Takahashi, Sean Carter, Michael W. Clarke, Mark A. Milad, Haruo Usuda, Hideyuki Ikeda, Yusaku Kumagai, Yuya Saito, Demelza J. Ireland, John P. Newnham, Masatoshi Saito, Alan H. Jobe, Matthew W. Kemp
Abstract
Lung maturation benefits in preterm lambs were progressively lost when fetal plasma betamethasone concentrations fell below 2 ng/mL. The effective floor threshold for a robust, lung-maturing exposure likely lies between 1 and 2 ng betamethasone per milliliter of plasma. Hypothalamic pituitary adrenal axis signaling and immunocyte populations remained materially disrupted at subtherapeutic steroid concentrations. These data demonstrate the potential to improve antenatal steroid therapy using reduced dose regimens informed by glucocorticoid pharmacokinetics and pharmacodynamics.