FDA staff says ADHD patch not safe enough

Reuters | December 1, 2005
By Susan Heavey

WASHINGTON - An experimental skin patch to treat attention deficit hyperactivity disorder in some children should not be approved in the United States because of safety risks, U.S. regulatory staff recommended on Thursday.

Two new studies for the patch, which is made by Britain's Shire Pharmaceuticals Group Plc and U.S. Noven Pharmaceuticals Inc. did not prove it was safe enough, Food and Drug Administration reviewers said in memos posted on the agency's Web site.

Shares of both Noven and Shire tumbled on the news.

In midday trading on Nasdaq, Noven shares were off 20.8 percent, or $2.81, to $10.70. Meanwhile, in London Stock Exchange trading, Shire closed near flat after earlier falling about 2 percent.

The staff review was released ahead of a meeting of FDA advisors Friday to consider whether to recommend approval of the patch. The FDA usually follows its panels' advice.

The patch, known as the methylphenidate transdermal system (MTS), aims to deliver via the skin a generic version of one of the most popular ADHD treatments -- Swiss drug maker Novartis AG's Ritalin.

FDA officials in April 2003 rejected the patch citing high rates of insomnia, anorexia and weight loss when used for 12 hours.

Since then, the companies conducted additional studies that they said showed MTS was safe and effective when used for nine hours. They hope to market it under the name Daytrana.

FDA reviewers on Thursday said the patch, designed for once-daily use in children 6 to 12 years old, still caused too many side effects.

MTS was also linked to a high risk of a muscle spasm disorder, or tic, and skin irritation, they wrote.

"The safety and tolerability profile of MTS treatment in these two new studies does not appear to be significantly more acceptable than that in the previous MTS submission," the staff said.

Company officials, in other documents released on Thursday, said the problems were no worse than with pill versions.

Thomas Laughren, head of the FDA's Division of Psychiatry Products, agreed most of the side effects were found with tablets, but in some instances occurred more with the patch.

Some FDA scientists also had concerns about the potential for children to abuse the patch by extracting the active ingredients with a solvent like alcohol, but others said it was unlikely.

Some reviewers with the agency's controlled substance division said extraction would be a complicated, time-consuming and expensive process that was most likely not worth the time or trouble by a would-be abuser for the resulting small amount of the drug.

The bigger threat, they said, was children sharing the patch. Still, "there would be no 'rush' from applying the patch" because it takes two to three hours to have an effect, the reviewers said.

Ritalin and its generic versions are one of the most commonly abused pills among youth, studies have shown.

The companies said the patch was not misused or shared during trials.

Between 73 percent and 82 percent of parents whose children participated in late-stage studies "strongly agreed that MTS afforded them control over their child's treatment and peace of mind over potential misuse," they said.

Last modified December 1, 2005