The acute effects of ritodrine infusion on maternal metabolism: measurements of levels of glucose, insulin, glucagon, triglycerides, cholesterol, placental lactogen and chorionic gonadotropin.

Twenty-nine women in premature labor were randomly assigned to a ritodrine (N = 14) or placebo (N = 15) treatment group. Thirteen serial blood samples were drawn during the first 12 hours of therapy by intravenous drug infusion and they were analyzed for a variety of metabolic substances. There was a significant increase in the blood glucose level in the ritodrine group after one hour and this persisted for the 12 hours of intravenous drug treatment. Plasma insulin levels similarly did not increase in the placebo but significantly rose in the ritodrine group by 30 minutes, peaked at 2 1/2 hours, and remained elevated throughout the infusion. There were no significant differences between levels of plasma glucagon, cholesterol triglyceride, human placental lactogen, or human chorionic gonadotropin in the two treatment groups. Ritodrine caused significant maternal and fetal tachycardia. Its use in women with carbohydrate abnormalities should be monitored carefully. The increased glucose levels may lead to an increased fetal weight.