Updated

The number of children taking antipsychotic medicines soared 73 percent in the four years ending in 2005, far outpacing the increase in adults, according to a Medco Health Solutions Inc. report released Tuesday.

Use of the new class of drugs known as atypical antipsychotics by people 19 and younger skyrocketed 80 percent in the same time period, according to the pharmacy benefit manager.

Antipsychotic drug prescriptions for that age group comprise a relatively small amount of the total for such medicines, Medco said. In 2005, 15 percent of prescriptions for such drugs were for children while 85 percent were for adults.

Still, the sharp increase is noteworthy because the powerful drugs are for individuals with serious psychosis such as schizophrenia so there is some concern the medicines may not always be prescribed appropriately, said Dr. Amita Dasmanapatra, senior director of medical affairs at Medco.

She said it is possible that some doctors are prescribing the drugs for children with behavioral problems, which would be better controlled by other means. Medco's analysis of over 2 million insured Americans didn't explore the reasons for the increase.

Additionally, the atypical antipsychotics aren't approved for use in children although doctors are free to prescribe drugs as they see fit.

The number of children on antipsychotics rose to 6.6 per 1,000 in 2005 from 3.81 per thousand in 2001. In contrast, 11 adults per 1,000 were taking one of the drugs. The increase in the number of adults taking antipsychotics rose 13 percent in the four years ended in 2005.

However, the rate of prescription growth in children has been slowing although the analysis was not designed to determine the reason.

For example, the rate of prescription growth in all antipsychotics was 3.38 percent last year, down from 14 percent in 2004 and 22 percent in 2003. Meanwhile, last year prescription growth for atypical antipsychotics was nearly 5 percent, down from nearly 13 percent in 2004 and 24 percent in 2003.

In adults, the number of prescriptions fell 7 percent.

Dr. David Kessler, a child and adolescent psychiatrist in Burlington, Vt., speculated that the decrease in growth is tied to concern about atypical antipsychotics link to diabetes.

In 2003, The U.S. Food and Drug Administration asked manufacturers of atypical antipsychotics to add warning labels describing the increased risk of high blood sugar and diabetes. The drugs include Eli Lilly & Co.'s Zyprexa, AstraZeneca PLC's Seroquel, Bristol-Myers Squibb Co.'s Abilify and Pfizer Inc.'s Geodon.

Also, last year the FDA determined that elderly patients with dementia that were being treated with atypical antipsychotics had an increased risk of death. The FDA asked manufacturers to include a warning on the drugs' label about the risk, and note that the drugs are not approved to treat behavioral problems in patients with dementia.