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.