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Human maternal and fetal plasma glyceryl trinitrate concentrations
Mark A Bustard1, Greg Ryan, Gareth Seaward
1Department of Pharmacology and Toxicology, Queen's University, Kingston General Hospital, 76 Stuart Street, Kingston, Ontario, Canada K7L 2V7.
American Journal of Obstetrics and Gynecology
|January 8, 2004
Summary
Transdermal glyceryl trinitrate (GTN) use during pregnancy results in low fetal GTN levels. Maternal GTN concentrations are measurable, but fetal levels remain below assay sensitivity, indicating minimal fetal exposure.
Area of Science:
- Pharmacology
- Obstetrics
- Maternal-Fetal Medicine
Background:
- Transdermal glyceryl trinitrate (GTN) is used tocolytically in pregnancy.
- Understanding maternal-fetal drug transfer is crucial for obstetric safety.
Purpose of the Study:
- To quantify maternal and fetal steady-state concentrations of GTN and its metabolites.
- To assess fetal exposure during transdermal GTN administration for obstetric indications.
Main Methods:
- Transdermal GTN (0.4 mg/h) applied prior to fetal blood sampling.
- Maternal venous (MV) and fetal venous (FV) plasma samples collected.
- Assays for GTN and dinitrate metabolites.
Main Results:
- Maternal steady-state GTN concentration: 4.3+/-0.84 nmol/L.
- Dinitrate metabolites detectable but not quantifiable in maternal plasma.
- GTN detectable but not quantifiable (<1 nmol/L) in fetal plasma.
Conclusions:
- The fetal/maternal GTN plasma concentration ratio is <0.23.
- Transdermal GTN administration results in minimal fetal GTN levels at the time of sampling.