Antidiuretic effect of ritodrine with and without beta-adrenergic blockade.

Dose-related effects of ritodrine and ritodrine combined with metoprolol on urinary excretion rate were studied in anesthetized dogs. Urine production was abruptly reduced after a total dose of 4 micrograms.kg-1 of ritodrine. This effect could not be antagonized by metoprolol, although the ritodrine-induced decrease of mean arterial pressure and renal arterial blood flow was significantly inhibited. The possible role of fluid retention during tocolytic treatment, even with beta-adrenergic blockade, in the etiology of pulmonary edema is discussed with a review on recent literature.