beta-Endorphin in obstetric analgesia.

Rapid and prolonged analgesia was obtained in all of 14 obstetric patients who received synthetic human beta-endorphin intrathecally at the time of delivery. Normal uterine contractions were maintained and all women were fully conscious and highly cooperative in the delivery process. No depression of respiration rate, cardiovascular or central nervous system was observed in any of the patients. Conditions of the infants evaluated by Apgar scoring were excellent. beta-endorphin must be administered intrathecally because it does not cross the blood-brain barrier; for the same reason, beta-endorphin cannot enter the central nervous system of the fetus as do opiates or other drugs commonly used as anesthetics or analgesics at the time of delivery.