[Risks of simultaneous tocolytic treatment with beta adrenergic and PG inhibiting agents]

Betaadrenergics are the most important agents in the treatment of premature labour. Often they are used in combination with steroids which promote fetal lung maturation and prevent respiratory distress syndrome in preterm infants. Because PG synthesis inhibitors also reduce uterine contractions they have been used as tocolytics whenever beta adrenergics alone fail. Several cases of pulmonary edema in otherwise healthy pregnant women have been reported following a combined tocolytic treatment with betaadrenergic drugs and PG synthesis inhibitors. The inhibited synthesis and function of renal PGs may be a very important factor contributing to those fatal events. Both, the ADH stimulating effect of beta adrenergics and the inhibition of the negative feed back mechanism of PGs on ADH action by blockade of PG synthesis potentiates renal water retention, thereby increasing the risk of water intoxication. Concerning the effects of maternal tocolytic treatment on the fetus or newborn, there is good evidence that PG inhibitors like aspirin or indomethacin can lead to closure of the ductus Botalli prior to birth and persistent pulmonary hypertension of the newborn. Severe cardiopulmonary adaption disturbances may be the consequence. Routine clinical use of PG synthesis inhibitors in combination with adrenergic stimulants cannot be recommended on the basis of available information.