The aim of this paper is to review available data about medicines for preventing preterm labour. 10, 11]. Moreover, even with selective 2 adrenergic receptor agonists, you will find significant maternal side effects reported such as tachycardia, dyspnoea, hypokalemia, hyperglycemia, and chest pain [5, 6, 9C12]. In conclusion, despite their effectiveness, 2 agonists’ security profile is a real concern responsible for therapy discontinuation and choosing alternative tocolytic medicines. 3.2. NO Donors NO is definitely a powerful vasodilator synthesized during an amino acid buy 218137-86-1 oxidation process catalysed by NO synthase. It is buy 218137-86-1 present in myometrial cells and raises cGMP content material by connection with guanylyl cyclase. There is a specific link between NO production and uterine relaxation [8, 9]. Transdermal nitroglycerin administration has been used in preterm labour but only in small series. It was associated to a better tocolytic effect than placebo on delaying delivery for two days. Its effect was much like ritodrine [2C5]. As there is no large randomized studies available, NO is not used in medical routine. 3.3. Magnesium Sulphate The relaxant effect of Magnesium sulphate in vitro and in vivo on human being uterine contractility has been widely reported. As magnesium is definitely a calcium antagonist, it decreases calcium intracellular concentration and inhibits contraction process [2, 4, 9]. However, in 2002, a meta-analysis based on 881 individuals did not evidence any good thing about Magnesium sulphate administration over placebo use in preterm labour . As the drug is definitely crossing the placenta, there were issues about fetal security. An increased risk of perinatal death and neonatal adverse effects including RAB11FIP4 neurological and metabolic disorders were reported in some tests using Magnesium sulphate treatment at high dose [6, 13]. It can also impact maternal neuromuscular system. Over a serum concentration of 9?mg/dL, there is a high toxicity risk resulting in respiratory major depression and disappearance of reflexes. There is no evidence any more to recommend this drug like a first-line tocolytic agent [2, 6, 13, 14]. However, when given prophylactically at low dose, it was reported to have a neonatal neuroprotective effect inside a randomized multicentre trial  but this effect should be confirmed in the next long term on large randomised controlled studies . 3.4. Prostaglandin-Synthase Inhibitors Prostaglandin-synthase or cyclooxygenase (COX) isoforms COX-1 and -2 are essential enzymes for transforming arachidonic acid to prostaglandins. Prostaglandins are well-known uterine contraction inducer by enhancing myometrial space junction and increasing intracellular calcium concentration [2, 4, 5, 9]. Indomethacin, a nonspecific COX inhibitor, has been reported in studies and in a recent buy 218137-86-1 meta-analysis to be an efficient tocolytic drug compared to placebo, significantly delaying preterm delivery . It can be administrated rectally or orally. Its use should be restricted in duration and limited to pregnancies below 32 weeks because of fetal ductus arteriosus closure risk and decreased urine production responsible for oligohydramnios [3, 5, 6, 17]. These treatments also have maternal side effects including gastric ulcer or asthma recurrence [3, 5, 6]. COX-2 inhibitors such as nimesulide or rofecoxib have been studied in animal but not yet in humans and are not actually recommended for avoiding preterm labour in medical practice . In conclusion, indomethacin is an efficient tocolytic drug with no serious adverse drug reaction and is indicated for short-term effect during the second trimester of pregnancy. 3.5. Oxytocin Receptor Antagonists These providers are in competition with the myometrial and decidual oxytocin receptors. The only drug used in medical practice is definitely atosiban. It blocks inside a reversive manner the intracytoplasmic calcium launch associated with contractions and downregulates prostaglandin synthesis [2, 9]. A first multicentric randomised trial comparing atosiban and ritodrine shown a similar tocolytic effect but fewer adverse effects with atosiban [4, 6]. A meta-analysis published in 2005 reported no benefit in terms of preterm delivery rate and neonatal.