Premature birth poses significant risks and burdens for both families and society as a whole. As a result, prevention and treatment of premature birth are of utmost importance. Tocolytics, such as atosiban, play a crucial role in delaying preterm labor and protecting the fetus. Atosiban, a cyclic nonapeptide and an oxytocin analogue, acts as a competitive antagonist of oxytocin receptors in the uterus, decidua, and fetal membranes. By inhibiting uterine contractions, atosiban has emerged as a valuable clinical tool in the treatment of premature birth.
Atosiban, as a combined oxytocin and vasopressin V1A receptor antagonist, offers a unique approach to inhibiting uterine contractions. The structural similarity between the oxytocin receptor and the vasopressin V1A receptor necessitates the simultaneous blockade of both receptor pathways to effectively inhibit uterine contractions. Unlike other tocolytics such as beta-agonists, calcium channel blockers, and prostaglandin synthase inhibitors, atosiban's dual receptor antagonism allows for more efficient inhibition of uterine contractions. Oxytocin, in addition to stimulating uterine contractions, also stimulates the production and release of PGF2α, which further contributes to uterine smooth muscle contraction. Atosiban's high affinity for the oxytocin and vasopressin V1A receptors competitively binds to these receptors, effectively blocking the action pathways of oxytocin and vasopressin. This mechanism leads to a reduction in uterine contractions.
One of the significant advantages of atosiban is its minimal side effects. While mild tachycardia, chest tightness, dizziness, headache, nausea, and dyspnea have been reported, these side effects generally require no special treatment, and the drug is rarely discontinued due to side effects. Furthermore, atosiban has a short plasma half-life, limiting its accumulation in the fetal circulation and reducing the risk of adverse effects on the fetus.Clinical trials have demonstrated the efficacy of atosiban in prolonging pregnancy in women with more than 28 weeks of gestation. In a multicenter, double-blind, placebo-controlled trial, atosiban treatment resulted in pregnancy prolongation of up to 7 days. Comparative clinical trials have also shown atosiban to have a comparable tocolytic action to ritodrine while being better tolerated, particularly in terms of maternal cardiovascular side effects. These findings highlight the potential of atosiban as an effective and well-tolerated tocolytic agent.
Atosiban, as a competitive vasopressin/oxytocin receptor antagonist, plays a vital role in preventing premature birth. Its ability to inhibit uterine contractions through dual receptor antagonism makes it a valuable tool for delaying preterm labor. The minimal side effects, short plasma half-life, and limited accumulation in the fetal circulation further enhance its safety profile. Additionally, atosiban's potential in improving pregnancy outcomes in patients with repeated implantation failure undergoing IVF-ET demonstrates its versatility and potential in reproductive medicine. Continued research and clinical utilization of atosiban could contribute significantly to reducing the burden of premature birth on families and society.
