By Natalie Engler

NEW YORK (Reuters Health) - Medications used to treat either a mother or child played a role in nearly 6,000 serious side effects, including 769 deaths, in children under 2 years of age in the US between 1997 and 2000, according to an analysis of cases reported to the Food and Drug Administration.

Medications given to pregnant or breast-feeding women may have caused a large proportion of adverse events, and just four drugs were the principal suspect in more than one third of all the reported deaths.

"The results of this study underscore the need for additional testing in the youngest pediatric patients and for greater vigilance in the use of higher risk drugs and in medication for pregnant and lactating women," the researchers report in the November issue of the journal Pediatrics. However, they note that the reports do not prove that the medication was the actual cause of the side effect or death.

Overall, the investigators identified 1,902 drugs, chemicals, biological products, vaccines, over-the-counter medications, vitamins, minerals, dietary supplements and other substances in the reports, but just 17 drugs were indicated in more than half of the serious side effects or deaths in children given medication directly.

The vast majority of deaths (84%) happened before the infant's first birthday.

In the study, Thomas J. Moore of George Washington University in Washington DC and his colleagues analyzed over 7,000 reports of adverse drug reactions in children under age 2 received by the US Food and Drug Administration from November 1997 through December 2000. Overall, 5,976 reports were new and unique cases that had not been reported previously.

They found that in 1,432 cases, or 24%, the drug or product had been given to the mother either during pregnancy, labor or while breast-feeding. The most common adverse effects in these cases were birth defects or disability in the child.

The top 10 list of drugs suspected as a cause of serious and deadly reactions when administered directly to children included treatments for respiratory syncytial virus, antibiotics and over-the-counter analgesics, such as acetaminophen and ibuprofen. Infection with RSV is common, and most people are infected by age 2 and experience cold-like symptoms that eventually improve without treatment. But in some infants and in adults with weakened immune systems or lung disease, the virus can cause pneumonia and other potentially life-threatening complications. RSV infection is the leading cause of hospital admissions in young children.

"Drugs have many important benefits. But this should make parents aware that all drugs--even familiar ones such as acetaminophen and ibuprofen--can sometimes have serious adverse effects," Moore said in an interview with Reuters Health.

This is the first time such data has been made available to pediatricians, said Moore.

Moore cautioned that the findings do not mean infants should stop receiving drugs when necessary. "The information in this study contributes to a much larger balance of risks and benefits that must be weighed in the decision whether to use a particular drug in a particular patient," he said.

He added that, while he has no data that compares the number of adverse reactions to the total number of infants given each medication, "serious adverse reactions to acetaminophen are rare."

Acetaminophen was suspect in just 1.6% of all serious adverse reactions to drugs administered directly.

Moore stressed that "these reports do not prove that the suspect drug directly caused the reported adverse event. Instead they should be considered a warning flag to encourage us to examine those drugs more carefully."

He added that they also underscore the need for more pediatric testing to more accurately measure drugs' risks and benefits.

SOURCE: Pediatrics 2002;110:e53.