Related Experiment Videos
Maternal kinetics of morphine during labour
E Gerdin1, T Salmonson, B Lindberg
1Department of Obstetrics and Gynecology, Akademiska Hospital, Uppsala University, Sweden.
Journal of Perinatal Medicine
|January 1, 1990
Summary
Parturients eliminate morphine faster than non-pregnant women, with a shorter half-life and higher clearance. This rapid morphine clearance may reduce fetal exposure during labor, impacting obstetric analgesic choices.
Area of Science:
- Pharmacology
- Obstetrics
- Clinical Pharmacy
Background:
- Parenteral morphine is used for pain relief during labor.
- Understanding morphine pharmacokinetics in pregnancy is crucial for maternal and fetal safety.
Purpose of the Study:
- To compare the disposition of parenterally administered morphine in nulliparous parturients versus healthy non-pregnant women.
- To assess the impact of pregnancy on morphine's pharmacokinetic parameters and metabolite formation.
Main Methods:
- Morphine administered intravenously or intramuscularly to 13 parturients and 6 non-pregnant women.
- Serial blood sampling up to 360 minutes post-dose, including umbilical cord blood at delivery.
- Plasma concentrations of morphine and morphine-3-glucuronide (M3G) were quantified.
Main Results:
- Shorter elimination half-life (43 vs. 84 min) and higher plasma clearance (3.4 vs. 2.0 L/min) of morphine in parturients.
- Faster M3G peak concentration time (11 vs. 21 min) and higher M3G/morphine ratio at 10 min in parturients.
- No detectable morphine in most infants, suggesting limited fetal exposure.
Conclusions:
- Parturients exhibit significantly faster morphine elimination compared to non-pregnant women.
- Rapid maternal morphine clearance may limit fetal exposure, potentially influencing the selection of obstetric analgesics.
- Further research could explore alternative analgesics with different pharmacokinetic profiles in laboring patients.