Human perinatal distribution of butorphanol

Area of Science:

• Pharmacology
• Obstetrics
• Neonatology

Background:

• Butorphanol is an analgesic used in obstetric care.
• Understanding its perinatal distribution is crucial for maternal and neonatal safety.

Purpose of the Study:

• To investigate the maternal-neonatal transfer of butorphanol.
• To quantify butorphanol excretion into breast milk.
• To assess the potential infant exposure to butorphanol via breast milk.

Main Methods:

• Maternal and neonatal serum concentrations were measured after parenteral butorphanol administration.
• Butorphanol levels in breast milk were analyzed following oral and intramuscular routes.
• Milk-to-serum concentration ratios were calculated.

Main Results:

• Butorphanol readily crosses the placental barrier, with neonatal serum levels comparable to maternal levels.
• The drug was detected in breast milk after both oral and intramuscular administration.
• Milk-to-serum ratios were 0.7 (intramuscular) and 1.9 (oral).
• Estimated daily infant exposure via breast milk was found to be negligible.

Conclusions:

• Butorphanol demonstrates favorable maternal-neonatal transfer and milk excretion characteristics.
• The safety and efficacy profile supports its use as an obstetric analgesic.
• Potential infant exposure is minimal, suggesting a good safety margin.