Oxytocin is a drug of choice for stimulating
contractions, which acts on the smooth muscle of the uterus and its responds,
depends on the threshold of excitability of the uterine. The posterior
pituitary along with ADH secretes oxytocin, which is similar to vasopressin that causes hypertension while synthetic oxytocin cause
hypotension when given as a rapid IV bolus. Some studies suggest that the
preservative chlorobutanol is responsible for these haemodynamic changes.
