STUDY: MEDICAL INGREDIENT HARMFUL

OMAHA, Neb. (AP) -- A key ingredient in cough syrups and tablets such as
Robitussin, Nyquil and Tylenol Cold caused severe defects in chicken
embryos and should be avoided by pregnant women, researchers warned Thursday.

However, other studies have shown no link between dextromethorphan and
birth defects in humans, and experts said more study is needed.

``I think it would take a lot more than chicken embryos to get me
concerned,'' said Dick Leavitt, director of science information at the
March of Dimes.

Dextromethorphan is in a wide variety of over-the-counter cold and flu
medications, including Tylenol Cold, Tylenol Flu, Vicks Dayquil, Robitussin
Maximum Strength, Sudafed Severe Cold Formula, Nyquil and Dimetapp DM.

The study, published in January's issue of the journal Pediatric Research,
used more than 3,000 chicken embryos to see how they were affected by three
classes of drugs called NMDA receptor blockers. All three classes generally
caused defects, but dextromethorphan was one of the worst.

``I would be telling my children don't take it, the defects are so
severe,'' said the leader of the study, Thomas H. Rosenquist, a biologist
and chairman of the University of Nebraska Medical Center's cell biology
and anatomy department.

Dextromethorphan stops coughing by blocking a receptor of the central
nervous system. However, in embryos it knocked out the receptor, causing
the defects, Rosenquist said.

Alcohol, already known to cause birth defects, does much the same thing,
said Dan Monaghan, a pharmacologist who also worked on the study.

``It's a lot like telling women not to drink alcohol. It stops this kind of
receptor,'' he said.

Ron Schmidt, a spokesman for McNeil Consumer Products Co., the maker of
Tylenol cold medication, noted the medication has a warning label urging
pregnant women to consult their doctor before using it.

While Rosenquist said early embryos of chickens are good indicators of what
happens in early development of human embryos, the March of Dimes' Leavitt
said more studies have to be done on mammals.

A 1977 study of 300 women exposed to the drug in their first four months of
pregnancy and a 1985 study of 59 women exposed to the drug in their first
trimester showed no problems.

In the new study, researchers gave three different levels of
dextromethorphan to 467 chicken embryos developed to the equivalent of
three to four weeks of a human embryo.

Of those, 21 percent died and 8 percent of the survivors developed some
kind of defect, including no brain, spina bifida and cleft palate.

In a control group of nearly 700 embryos, only 1.5 percent died and 1
percent developed defects.

Of 104 embryos that survived and received a dose of dextromethorphan
estimated at what would reach a human embryo if a pregnant woman used one
recommended dose of cough medicine, 7 percent developed defects.

``There was no level at which there was never a defect,'' Rosenquist said.
``We feel that a single dose is capable of causing a birth defect and that
ultimately it could be the cause of a woman to have a miscarriage.''