For the treatment and prophylaxis of premature labour
Ritodrine is beta-2 adrenergic agonist. It binds to beta-2 adrenergic receptors on outer membrane of myometrial cell, activates adenyl cyclase to increase the level of cAMP which decreases intracellular calcium and leads to a decrease of uterine contractions.
LD<sub>50</sub>=64mg/kg (mice, IV); LD<sub>50</sub>=540 mg/kg (mice, oral); LD<sub>50</sub>=85 mg/kg (rat, IV)
1.7-2.6 hours