Mothers have always warned children not to take candy from strangers. Now a health research group is issuing the same caution to the federal Food and Drug Administration.

Public Citizen Health Research Group has asked the FDA to stop clinical studies in Salt Lake City in which children facing painful diagnostic procedures, such as bone marrow biopsies, or going into surgery with a general anesthetic are given a sucker-like item laced with a potent narcotic.In a letter to the FDA, the group warned that the drug, which they say is in the form of a lollipop, sends children "a dangerous message" about drugs being candy and is of "dubious clinical need or safety."

Officials at Anesta Corp., established by Dr. Theodore H. Stanley, anesthesiology professor; business executive William C. Moeller; and the University of Utah (which owns the patent) have defended the study and discount the potential for drug abuse.

The narcotic, fentanyl, has been approved as safe and effective as an injectable drug by the FDA for about 20 years, they said.

In the local FDA-approved study, it is mixed with sweeteners, mounted on a stick and administered orally to children before they are given general anesthesia or undergo a painful diagnostic procedure. It's a premedication sedative and analgesic.

Anesta scientists began their study 31/2 years ago and will continue for a year or two more before the company seeks approval to market oral transmucosal fentanyl citrate (OTFC) commercially.

To date, the FDA has not approved the oral form of the drug except for use in the controlled clinical studies.

The citizens health group hopes that never happens. "Giving lollipops laced with a powerful narcotic to children, who, in the words of one research group `visibly enjoyed the premedication experience,' as one might expect children sucking lollipops to do, is a major step in the wrong direction," said Sidney M. Wolfe, director of the health research group.

Wolfe also said approving oral use of the drug would likely increase drug abuse.

Local scientists disagree.

"Dr. Stanley and I are more concerned than anyone regarding drug-abuse problems in our society. OTFC and drug abuse are two very different issues," Moeller said. "Picture yourself the parent of a terrified, highly stressed child about to have painful surgery. Or picture your child having a bone marrow biopsy being held down by six orderlies.

"Wouldn't you want the same analgesic or sedative drug that adults frequently receive for pain relief, stress and a safer anesthetic in a similar circumstance?"

Moeller said OTFC is a simple, more humane way to give the proven drug fentanyl to children.

He added that this form of the drug has several advantages over the use of premedication sedatives delivered by needle.

It reduces stress in children who are about to undergo anesthesia. Instead of fearing an injection, the child simply sucks on the dosage unit and dozes off. The result is, a calm patient is delivered for anesthesia.

Also, the drug's analgesic properties reduce the need for high concentrations of inhalation drugs that depress the heart. It, therefore, makes the procedure safer for the child, he said.

Delivering the drug in the sucker form gives the doctor greater control over dosage, Moeller said, because if the drug is having a rapid effect, the doctor can remove the rest of the dose before it is consumed _ something you can't do with an IV needle. It also doesn't produce the "high" that an IV injection of fentanyl can.

"There's been no problem with abuse nor do we foresee it as a potential problem," Moeller emphasized. "Medicine including narcotics taken by mouth have been historically put in substances that taste good. That isn't anything new."

More than 400 people, mostly children, have been part of the study.