Hemodynamic and metabolic effects after nifedipine and ritodrine tocolysis.

ABSTRACT

OBJECTIVES: The purpose of this study is to compare the hemodynamic and metabolic changes after ritodrine and nifedipine tocolysis. METHODS: For an open randomized study, patients with preterm labor (N=185) were allocated to groups to receive ritodrine intravenously (N=90) or nifedipine orally (N=95). RESULTS: The mean diastolic blood pressure was significantly lower in the ritodrine group 24 h (65+/-12 vs. 70+/-8, P=0.001) and 48 h (65+/-12 vs. 71+/-8, P=0.004) after starting tocolysis compared with the nifedipine group. Mean maternal heart rate was significantly higher in the ritodrine group 24 h (105+/-17 vs. 86+/-13, P<0.0001) and 48 h (100+/-21 vs. 85+/-12, P<0.0001) after starting tocolysis compared with the nifedipine group. Mean fasting glucose levels were higher (6.68+/-2.53 vs. 4.93+/-1.23, P=0.0016), while mean potassium levels were lower (3.52+/-0.84 vs. 3.81+/-0.45, P=0.04) in the ritodrine group 48 h after starting tocolysis compared with the nifedipine group. CONCLUSIONS: Use of nifedipine for preterm labor is associated with a lower incidence of adverse hemodynamic and metabolic changes compared with ritodrine after 24 and 48 h of tocolysis. In our opinion nifedipine is the preferred drug of choice for the treatment of preterm labor.