By Alison McCook
NEW YORK (Reuters Health) Sept 02 - More than 90% of drugs approved
since 1980 have not been properly tested to rule out possible
teratogenic effects, study findings show.
Animal testing is the first step to determine if a drug is a
possible teratogen. After drug approval, careful follow-up studies are
still needed to confirm the drug's safety.
However, Drs. J. M. Friedman and W. Y. Lo, from the University of
British Columbia in Vancouver, Canada, found that for the vast
majority of new drugs these follow-up studies have not been performed.
As such, more than 90% of new drugs are still considered to have an
"undetermined" risk of producing birth defects, according to the
report in the September issue of Obstetrics & Gynecology.
"My experience is that many members of the general public, both
pregnant women and their partners, are surprised and frustrated about
how little we really know about the safety of medications in
pregnancy," Dr. Friedman told Reuters Health.
The solution, Dr. Friedman said, is simply to keep track of what
effects the drugs have in pregnant women who take them. "I would like
to see an ongoing effort to obtain information about the effects on
the baby of maternal use of prescription medications in human
pregnancy," he added.
The authors base their findings on a review of information
regarding the birth defect risk of 468 drugs approved between 1980 and
2000. They found that 91% of these new drugs were designated as
carrying an "undetermined" risk of birth defects if taken by pregnant
Dr. Friedman said that the companies that manufacture the drugs
often have no financial incentive to conduct further studies on birth
defects once the drug is FDA-approved. Proper studies cost money, the
researcher noted, and there is usually no regulatory requirement that
the companies perform these tests.
Studies could follow a group of pregnant women and record what
medications they take and the subsequent health of their infants, or
interview parents of infants with birth defects and determine which
medications the mothers took, Dr. Friedman suggested.
"The point is that such studies are possible, and I believe that
they need to be done on a sufficient scale to learn about the safety
of all medications in human pregnancy," he emphasized.
Obstet Gynecol 2002;100:465-473.