Effect of drugs used in obstetrics on the constriction by oxygen of the ductus arteriosus of the rabbit fetus.

The tone of the ductus arteriosus of the rabbit fetus near term constricted by oxygen (PO2 = 20 kPa) was relaxed reversibly by the drugs chlorpromazine, promethazine, drotaverine, papaverine, diazepam, propanidid, isoxsuprine, pethidine, 5-ethyl-5-(1-methyl-propyl) 2-thiobarbituric acid, and furosemide. Ethyl alcohol, on the other hand, caused constriction of the fetal ductus arteriosus. These drugs if used in obstetrics may disturb the newborn's adaptation to extrauterine life by inhibiting the postnatal closure of the ductus arteriosus. On the other hand, the constrictive effect of alcohol may adversely affect the fetus. The results make it necessary to investigate the effect of the drugs applied during the perinatal period on the adaptation of newborns to extrauterine life.