Oxytocin, also known as oxytocin, is a uterine contraction drug that can be extracted or chemically synthesized from the posterior lobe of the pituitary gland of animals. The chemical synthesis does not contain vasopressin, has no pressor effect, and has selective excitatory effect on uterine smooth muscle to enhance its contraction. The uterus in labor is most sensitive to oxytocin (increased estrogen secretion), and the immature uterus is not responsive to this product. Uterine responsiveness to oxytocin is low in the first or second trimester of pregnancy, but increases gradually in the second trimester and peaks before labor. Small doses can strengthen the rhythmic contraction of the smooth muscle at the bottom of the uterus, strengthen its contraction force, accelerate the contraction frequency, and the contraction nature is similar to natural labor, and maintain polarity and symmetry, so it is clinically used for oxytocin and induced labor. The large dose makes the uterine muscle show tonic contraction, which is clinically used to compress the blood vessels between the muscle fibers, prevent postpartum hemorrhage and postpartum rehabilitation insufficiency, and promote lactation, shrink the mammary duct, and promote milk discharge from the breast, but can not increase the secretion of milk, only promote milk discharge. It should be noted that the dose and drop speed should be strictly controlled when used for oxytocin or induction of labor, so as not to cause tetanic uterine contraction, resulting in fetal asphyxia death or uterine rupture. It is prohibited when the head basin is not balanced, the fetus is not in the right position or other abnormalities of the birth canal, poor uterine contraction, a history of cesarean section and more than 3 times of menstruation. The oxytocin preparations isolated from the pituitary of cattle and pigs can cause allergic reactions, and the rapid infusion can cause mild vasodilation and drop blood pressure. The fastest drop rate is not more than 40 to 60 drops per minute. A larger dose is also used for postpartum hemorrhage, fetal overgrowth, etc. In recent years, it has been found that this product has a good effect on pulmonary hemoptysis, and has a good effect on gastrointestinal dysfunction after vagectomy or abdominal operation. Oral administration is ineffective, easy to be destroyed by digestive fluid, but can be absorbed by the oral mucosa, intravenous infusion of 0.01IU in 1 to 3 minutes can cause the physiological contraction of the uterus (rhythmical, polar, symmetrical), holding time is short, half-life is only 2.5 to 3 minutes, large doses make the uterine muscle show tonic contraction. It has a synergistic effect with prostaglandins. Uterine contractions are often combined with ergot preparations to treat postpartum hemorrhage; Abortion is inevitable; It is mainly used for late pregnancy induced labor and delayed labor caused by uterine contraction weakness during labor. For oxytocin sensitivity test; For oxytocin irritation test; Assist postpartum milk discharge; Hemoptysis; Postoperative gastrointestinal peristalsis was delayed.