title: Do tocolytic agents stop preterm labor? A critical and comprehensive review of efficacy and safety.
abstract: OBJECTIVE
  Our aim was to determine the efficacy and safety of tocolytic agents currently used to treat premature labor.
  
  
  METHODS
  We carried out a comprehensive review of tocolytic agents in the treatment of premature labor. Three hundred twenty-eight studies published between 1933 and 1992 were analyzed.
  
  
  RESULTS
  An analysis of randomized, placebo-controlled, clinical trials showed that magnesium sulfate is not better than placebo in the treatment of premature labor. beta-Adrenergic receptor agonists effectively stop premature labor for only 24 to 48 hours. Calcium channel blockers and oxytocin antagonists inhibit uterine contractions, but their role in stopping labor is undefined. Prostaglandin inhibitors appear to be effective in treating premature labor and have few adverse side effects.
  
  
  CONCLUSIONS
  The only tocolytic drugs that might be effective are the prostaglandin inhibitors. Tocolytic agents should be used only between 24 and 32 completed weeks of gestation. Magnesium sulfate should not be used to treat premature labor. Oxytocin antagonists should be used only in experimental clinical trials. Calcium channel blockers and beta-adrenergic receptor agonists inhibit uterine contractions but do not prolong gestation for longer than 48 hours.
authors.affiliation: Department of Obstetrics and Gynecology, University of Texas Health Science Center, San Antonio 78284.
authors.forename: K
authors.initials: K
authors.lastname: Higby
authors.forename: E M
authors.initials: EM
authors.lastname: Xenakis
authors.forename: C J
authors.initials: CJ
authors.lastname: Pauerstein
mesh_terms: D000318:Adrenergic beta-Agonists / Q000627:therapeutic use; D002121:Calcium Channel Blockers / Q000627:therapeutic use; D005260:Female; D006801:Humans; D008278:Magnesium Sulfate / Q000627:therapeutic use; D007752:Obstetric Labor, Premature / Q000517:prevention & control*; D010121:Oxytocin / Q000037:antagonists & inhibitors; D011247:Pregnancy; D011448:Prostaglandin Antagonists / Q000627:therapeutic use; D016032:Randomized Controlled Trials as Topic; D015149:Tocolytic Agents / Q000009:adverse effects / Q000627:therapeutic use*
chemical_list: D000318:Adrenergic beta-Agonists; D002121:Calcium Channel Blockers; D011448:Prostaglandin Antagonists; D015149:Tocolytic Agents; D010121:Oxytocin; D008278:Magnesium Sulfate