Results of double-blind, multicentre study with ritodrine in premature labour.

A double-blind placebo-controlled multicentre study with ritodrine, a beta-mimetic uterine relaxant, has been performed in 91 patients in premature labour. All patients were treated according to a fixed dosage scheme consisting of an intravenous infusion followed by oral tablets for a total of seven days. Ritodrine arrested premature labour in 80%, the placebo in 48% of the patients (P=0.02). This short treatment, however, was usually not sufficient to prolong gestation till term. Apart from a slight to moderate rise in maternal heart rate and a slight rise in systolic blood pressure, ritodrine did not give rise to any maternal or fetal side effects. The problems of patient selection and of evaluation of the results are discussed.