Tocolytic agents are medicines that are given to women in preterm labor to prolong pregnancy for at least 48 hours to enable administration of antenatal corticosteroids, magnesium sulfate, or buy a bit more time for maternal transport to a tertiary care facility. Tocolytics have been shown to improve infant morbidity and mortality rates. Tocolytics may also be called anti-contraction medications or labor suppressants.
Terbutaline has been one of the most commonly used tocolytic agents. Through an action on beta2 receptors, terbutaline increases cyclic AMP, which decreases intracellular calcium levels, thereby decreasing myometrial contractility (the myometrium is the middle layer of the uterine wall and is responsible for inducing uterine contractions). Terbutaline should not be used to treat premature labor that has already lasted more than 48 to 72 hours. Benefits of terbutaline must also be weighed up against its risks, as serious and sometimes fatal side effects have been reported after the use of terbutaline in pregnant women.
