Different effects of tocolytic medication on blood pressure and blood pressure amplification

Background The importance of tocolysis has been discussed extensively. Beta-2 adrenoceptor agonistic drugs like ritodrine have been the reference tocolytic drugs in most countries. Cardiovascular side-effects are frequent. Atosiban, a newer tocolytic drug, is a competitive antagonist of oxytocin and has fewer cardiovascular side effects. Although large studies exist, there is mainly subjective reporting of adverse reactions with a focus on blood pressure data. Objectives Evaluation of the acute effects of therapeutic doses of ritodrine and atosiban in comparison to placebo on central and peripheral blood pressures, central-to-peripheral blood pressure amplification and the augmentation index (AIx) in healthy non-pregnant female volunteers. Methods A double-blind, randomized, crossover trial was carried out in 20 healthy non-pregnant female volunteers. Hemodynamic measurements were performed under standardized conditions. Results At steady state, central and peripheral pressures did not differ from placebo in the atosiban group. During ritodrine-infusion, central SBP increased by 11% versus placebo (p = 0.012) and peripheral SBP by 10% (p = 0.004). In contrast to atosiban and placebo, blood pressure amplification was absent in the ritodrine group. While the AIx did not change in the atosiban group, with ritodrine, the AIx tended to decrease. Conclusions The present study shows the significant effects of ritodrine on the cardiovascular system. Atosiban has no significant effects and may be an appropriate alternative to tocolyticum, particularly in cardiovascularly complicated pregnancies.