title: Glyceryl trinitrate and ritodrine in tocolysis: an international multicenter randomized study. GTN Preterm Labour Investigation Group.
abstract: OBJECTIVE
  To compare the efficacy of transdermal glyceryl trinitrate and intravenous (IV) ritodrine as tocolytics.
  
  
  METHODS
  Two hundred forty-five women with preterm labor and intact membranes between 24 and 36 weeks' gestation were randomized to transdermal glyceryl trinitrate or intravenous ritodrine. Treatment was continued until contractions stopped or a maximum of 7 days. Glyceryl trinitrate was administered as a 10- or 20-mg transdermal patch. Intravenous ritodrine was administered according to nationally available guidelines. The primary outcome was prolongation of gestation expressed as a percentage of the time from entry to 37 weeks. Secondary outcomes were proportion of women who delivered the same day, next day, or within 7 and 14 days of entry, and by 32, 34, and 37 weeks. Analysis was by intention to treat.
  
  
  RESULTS
  Twelve women (5%) were lost to follow-up. Glyceryl trinitrate and ritodrine prolonged gestation by 74% of time to 37 weeks (difference glyceryl trinitrate-ritodrine 0%; 95% confidence interval (CI) -10%, +10%). There was no significant difference in the proportion of women receiving glyceryl trinitrate or ritodrine who delivered within the specified days from study entry or weeks of gestation; however, 42 women who received glyceryl trinitrate and 58 women who received ritodrine delivered by 37 weeks (difference -11%; 95% CI -24%, +2%). No serious maternal side effects were reported for ritodrine or glyceryl trinitrate.
  
  
  CONCLUSIONS
  We found no overall difference between glyceryl trinitrate and ritodrine in the acute tocolysis of preterm labor but a suggested advantage of glyceryl trinitrate over ritodrine in reducing preterm delivery rate. The maternal side effect profile and treatment discontinuation rates were fewer for glyceryl trinitrate, suggesting it was a safer alternative to ritodrine.
authors.affiliation: Harris Birthright Research Centre, King's College Hospital, London, United Kingdom. cclees@computserve.com
authors.forename: C C
authors.initials: CC
authors.lastname: Lees
authors.forename: A
authors.initials: A
authors.lastname: Lojacono
authors.forename: C
authors.initials: C
authors.lastname: Thompson
authors.forename: L
authors.initials: L
authors.lastname: Danti
authors.forename: R S
authors.initials: RS
authors.lastname: Black
authors.forename: P
authors.initials: P
authors.lastname: Tanzi
authors.forename: I R
authors.initials: IR
authors.lastname: White
authors.forename: S
authors.initials: S
authors.lastname: Campbell
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D005996:Nitroglycerin / Q000627:therapeutic use*; D007752:Obstetric Labor, Premature / Q000517:prevention & control*; D011247:Pregnancy; D012312:Ritodrine / Q000627:therapeutic use*; D015149:Tocolytic Agents / Q000627:therapeutic use*
chemical_list: D015149:Tocolytic Agents; D005996:Nitroglycerin; D012312:Ritodrine