Administration Of Ritodrine Research Articles

PREMATURE LABOR TREATMENT WITH RITODRINE IN MULTIPLE PREGNANCY WITH THREE OR MORE FETUSES

Modern treatment for anovulatory infertility increases the incidence of multiple pregnancies with three or more fetuses and predisposes to prematurity with high perinatal mortality and mortidity. Premature labor was successfully treated in four multifetal pregnancies with ritodrine hydrochloride, a beta-mimetic drug relaxing the uterus. Another patient misdiagnosed as false labor was not treated and lost three out of four premature babies. Beta-mimetic treatment is indicated in multiple pregnancies even in false labor, or when painless progress in cervical dilatation is observed, to avoid asymptomatic progression into true labor. In contrast to singleton pregnancies, advanced labor with more than four centimeters cervical dilatation should not preclude good chances for successful treatment. Persistence in treatment and repreated use of the most effective intravenous route combined with oral ritodrine administration is needed because of marked tendency to recurrences of premature labor. Progressive increase in the dose of oral ritodrine may be indicated by decrease in therapeutic response. Maternal tachycardia should be considered as an index of patient responsiveness to the beta-mimetic treatment. The therapy is most successful when the patient is hospitalized from the first episode of treatment until at least the 37th week of pregnancy. This is probably less expensive than prolonged hospitalization of several prematures in an intensive care nursery.

Cardiac output and its distribution and organ blood flow in the fetal lamb during ritodrine administration

The response of the fetal circulation to beta adrenergic stimulation with ritodrine hydrochloride has been investigated by long-term monitoring of the fetal lamb in utero. Ritodrine was infused intravenously either into the ewe or directly into the fetus, and cardiovascular and acid-base responses were measured. Fetal cardiac output and its distribution were measured with the use of radionuclide-labeled microspheres. The output of each ventricle also was measured by means of long-standing implanted electromagnetic flow transducers around the ascending aorta or pulmonary trunk during infusion of ritodrine at various rates into the fetus. Infusion of ritodrine (1.9 mcg. per kilogram per minute) into the ewe caused no change in fetal heart rate, blood pressure, cardiac output, or umbilical blood flow, but did cause an increase in fetal adrenal and myocardial blood flow. Ritodrine infused directly into the fetus produced a marked increase in fetal heart rate and a minimal change in cardiac output. There were no significant changes in fetal or maternal acid-base balance during the ritodrine infusions.

A study of indomethacin combined with ritodrine in threatened preterm labor

A prospective and double-blind study was undertaken to compare the effectiveness of two different treatments on two randomized groups of patients with threatened preterm labor. The first treatment consisted of the administration of ritodrine and a placebo; in the second, ritodrine was combined with indomethacin. 22 patients were evaluated in each group. The results obtained for gain in days, number of patients delivered at term, weight of newborns and number of recurrences in each group suggest that treatment with ritodrine and indomethacin is slightly but significantly more effective than treatment with ritodrine and placebo in prolonging pregnancy. No evidence has been found of possible unfavorable vascular effects of indomethacin in the fetus or the newborn.

PREMATURE LABOR TREATMENT WITH RITODRINE IN MULTIPLE PREGNANCY WITH THREE OR MORE FETUSES

Modern treatment for anovulatory infertility increases the incidence of multiple pregnancies with three or more fetuses and predisposes to prematurity with high perinatal mortality and mortidity. Premature labor was successfully treated in four multifetal pregnancies with ritodrine hydrochloride, a beta-mimetic drug relaxing the uterus. Another patient misdiagnosed as false labor was not treated and lost three out of four premature babies. Beta-mimetic treatment is indicated in multiple pregnancies even in false labor, or when painless progress in cervical dilatation is observed, to avoid asymptomatic progression into true labor. In contrast to singleton pregnancies, advanced labor with more than four centimeters cervical dilatation should not preclude good chances for successful treatment. Persistence in treatment and repreated use of the most effective intravenous route combined with oral ritodrine administration is needed because of marked tendency to recurrences of premature labor. Progressive increase in the dose of oral ritodrine may be indicated by decrease in therapeutic response. Maternal tachycardia should be considered as an index of patient responsiveness to the beta-mimetic treatment. The therapy is most successful when the patient is hospitalized from the first episode of treatment until at least the 37th week of pregnancy. This is probably less expensive than prolonged hospitalization of several prematures in an intensive care nursery.

Effects of prolonged infusion of β-adrenergic agonists on uterine and umbilical blood flow in pregnant sheep

We have extended our evaluation of the effects of three β-adrenergic agents in near-term pregnant sheep to include a period of infusion three times longer than previously studied. This extension has provided the following information: (1) Initial depression of uterine blood flow and mean arterial pressure associated with administration of ritodrine or salbutamol abate with time despite continued drug infusion; (2) the uterine hyperemia associated with salbutamol and fenoterol are drug-related rather than postinfusion-related phenomena; (3) increased uterine vascular resistance is found with ritodrine, and decreased uterine vascular resistance occurs with salbutamol and fenoterol.

A double-blind investigation into the effects of ritodrine on uterine blood flow during the third trimester of pregnancy

The object of this double-blind crossover study was to investigate the effect of a beta-mimetic agent-ritodrine-administered intravenously at increasing infusion rates on uterine blood flow and the maternal cardiovascular system during the third trimester of normal pregnancies and pregnancies complicated by intrauterine growth retardation and/or hypertension. Uterine blood flow, maternal arterial blood pressure, maternal and fetal heart rate, and uterine activity were simultaneously recorded throughout the study. In normal pregnancies the changes in different parameters during ritodrine and placebo administration were slight. In the "pathologic" pregnancies there was a highly significant increase in maternal heart rate, differential blood pressure, and uterine blood flow during ritodrine administration. The differences in response to ritodrine and placebo were statistically significant in this later group. This study demonstrates increased sensitivity of the maternal cardiovascular system to this beta-mimetic agent in certain categories of high-risk pregnancies and possibily an increase in uteroplacental blood flow.

The influence of ritodrine on glucose and insulin blood levels after oral glucose loading in the last three months of normal pregnancy

By a t-test for paired observations the influence of ritodrine, a β-sympathicomimetic drug which is administered as a tocolytic, on the blood glucose concentrations and the insulin secretion of women in their last 3 months of pregnancy, whose metabolism was normal, was demonstrated by means of the oral glucose tolerance test. Upon administration of ritodrine, the insulin levels as well as the mean glucose values significantly exceed the results obtained from the standard glucose tolerance test. In 12 out of 21 patients abnormally high blood glucose levels were encountered following additional administration of ritodrine.