Methods
Patients A cross-sectional pharmacokinetic study of singleton and twin
pregnancies was performed, including pregnant women underwent tocolysis
in the local hospital because of preterm labour from August 2018 to
September 2019. This study was approved by the local Ethics Research
Committee (protocol number 8676/2017) of University Hospital of the
Ribeirão Preto Medical School (São Paulo, Brazil), and patients gave
signed informed consent. The study protocol was registered on the
Brazilian Registry of Clinical Trials (ReBEC,
www.ensaiosclinicos.gov.br) under ID number RBR-2v2mwkz. Participation
in the study was limited to the inpatient population to ensure
compliance with serial blood sampling. Thirty-five pregnant women,
between 24 and 34 weeks of gestation, and >18 years old
were clinically eligible for the antenatal corticosteroid treatment and
were approached for enrollment. The following exclusion criteria were
applied: use of tobacco, alcohol or illegal substances; maternal
diseases with vasculopathy identified by laboratory tests or signals of
placental insufficiency; the use of drugs that interact with BET; or
maternal desire to withdraw. Finally, the data from 26 pregnant women,
divided into three groups (9 singleton pregnancies, 9 DC and 8 MC twin
pregnancies) were analyzed.