FDA Urged to Reconsider Use of Birth-Delaying Drug : Medicine: Researchers say ritodrine doesn’t increase pre-term baby’s chances of survival, and poses risks to the mother. But they have few other treatments to offer.

An editorial in today’s edition of an influential medical journal calls on the U.S. Food and Drug Administration to reconsider its approval of ritodrine, a drug administered to 100,000 pregnant women each year to forestall premature delivery--the most important cause of infant death from low birth weight.

The editorial in the New England Journal of Medicine, written by two obstetricians from the University of Texas Southwestern Medical School, accompanies a report of a Canadian study that shows that ritodrine does not stop uterine contractions long enough to significantly help a pre-term baby’s chances of survival.

At the same time, the drug can cause complications for the mother, including increased heart rate and the life-threatening accumulation of fluid in the lungs.

In the five-year study of 708 women at six hospitals, ritodrine was found to stop contractions, but only for 24 to 48 hours. The infant death rates were similar in two groups of patients: 352 who received ritodrine and 356 who took a placebo.

The editorial and the study, the largest ever conducted on a drug used to inhibit early labor, have focused attention on a long-running controversy over the use of drugs to prevent premature deliveries.

No matter which side they take, experts said that the study points up the importance of non-drug treatment--including an emphasis on more rest for women in the later stages of pregnancy and confinement to bed for those who are experiencing early contractions.

“The basic idea that we can stop premature labor in a woman who comes in huffing and puffing--that is what has really gone out the window,” said T. Murphy Goodwin, an obstetrician at USC.

Beyond that sentiment, even the doctors involved in the companion articles are at odds. Kenneth J. Leveno, a co-author of the editorial, said in an interview, “If it doesn’t affect the baby’s chances much, and there is potential for harm, ritodrine should not be used for this purpose.”

Jean-Marie Moutquin, a member of the Canadian Preterm Labor Investigators Group, disagreed. “The big question is, what can we do within 48 hours to improve the baby’s health? Should we do something else? There’s a lot of research to be carried out. But that does not mean reject the drug.”

Many doctors start steroid therapy to speed up development of the baby’s lungs during the extra time in the womb that ritodrine buys. This may help prevent serious lung disease after birth. But Moutquin said even the use of that therapy did not increase the percentage of pre-term babies surviving in the ritodrine group compared to the placebo group. He said he did not understand why.

Still, Moutquin, an obstetrician at Laval University in Quebec, compared ritodrine to “a car that has a problem with the transmission. You don’t reject the car; you try to get the transmission fixed.”

He added that doctors in Canada and Europe have been more cautious in the amounts of ritodrine prescribed and the conditions under which it is administered. In the United States, he said, “the drug has been used extensively with perhaps not enough care.”

March of Dimes Birth Defects Foundation President Jennifer L. Howse said in a statement that researchers should concentrate on finding out what triggers early labor in the first place. Until that process is better understood, she said, it will be difficult to develop effective treatments.

Ritodrine was approved by the FDA in 1980. It is the only drug approved specifically to curtail early labor. But in practice, physicians also prescribe other medicines that are FDA-approved but for other purposes. None seem to be more effective than ritodrine; each has its own set of drawbacks.

“The only reason this study doesn’t kick ritodrine right out the door is because there’s nothing to replace it,” Goodwin said.

Ritodrine works by affecting beta receptors, which are present in the lungs, heart and uterus. The drug speeds up the heart, but relaxes the lungs’ airways and the uterus, easing contractions.

USC and several other medical research centers are studying a possible substitute, atosiban, which inhibits oxytocin, a hormone thought to induce labor. Goodwin said he suspects the drug will not stop labor any longer than ritodrine does, “but it will have far fewer side effects.”

Goodwin said he doubts the report will prompt him to abandon ritodrine.

“I keep the ritodrine in my back pocket. I have nothing else to offer,” he said, adding that he would use the drug on his wife.

But, he said, “I may find myself talking more to patients” about the decision. “I might have a few more patients who decide not to use it. It will reduce use of the drug among the babies that are bigger.”