Nifedipine versus ritodrine for suppression of preterm labor. Comparison of their efficacy and secondary effects.
OBJECTIVE
To compare the efficacy of nifedipine and ritodrine in prolonging pregnancy beyond 48 h, 1 week and 36.0 weeks and to evaluate maternal side effects and adverse perinatal outcome.


METHODS
Non-blinded, randomized controlled trial. Eighty patients with singleton pregnancies admitted for preterm labor with intact membranes between 22 and 35 weeks of gestation were included in the study. Preterm labor was defined as the persistence of at least two symptomatic uterine contractions within a 10 min period during 60 min after admission and despite bed rest.


RESULTS
Forty women received oral nifedipine and forty intravenous ritodrine. Two patients, one from each group, were excluded because of loss to follow-up after discharge. Therefore, 39 women in the nifedipine and the ritodrine groups, respectively, were evaluable for the final analysis. Baseline characteristics were comparable in both groups. The percentage of initial response, the speed of onset of action and the rate of successful treatment within 48 h were significantly better in the ritodrine group. However, prolongation of pregnancy beyond 7 days and 36 weeks of pregnancy was similar with a significantly lower rate of side effects in the nifedipine group.


CONCLUSIONS
In this small trial, ritodrine provided more effective tocolysis within the first 48 h than nifedipine at the doses used in this study, although with a significantly higher rate of side effects.
Cararach
Vicenç
V
Institut Clínic de Ginecologia, Obstetrícia i Neonatologia, Hospital Clínic de Barcelona, Sabino de Arana 1, 08028 Barcelona, Catalonia, Spain.
Palacio
Montse
M
Martínez
Sergi
S
Deulofeu
Pere
P
Sánchez
Myriam
M
Cobo
Teresa
T
Coll
Oriol
O
D000284:Administration, Oral; D000328:Adult; D005260:Female; D005865:Gestational Age; D006801:Humans; D007262:Infusions, Intravenous; D009543:Nifedipine / Q000009:adverse effects / Q000627:therapeutic use*; D007752:Obstetric Labor, Premature / Q000517:prevention & control*; D010298:Parity; D011247:Pregnancy; D011256:Pregnancy Outcome; D012312:Ritodrine / Q000009:adverse effects / Q000627:therapeutic use*; D015149:Tocolytic Agents / Q000009:adverse effects / Q000627:therapeutic use*; D016896:Treatment Outcome
D015149:Tocolytic Agents; D012312:Ritodrine; D009543:Nifedipine