Milwaukee ? A new skin patch to treat Parkinson’s disease safely released a new drug and significantly improved symptoms, according to a study by researchers at the Medical College of Wisconsin and several other institutions.

By using a transdermal patch instead of conventional oral medication, doctors hope to get better control of Parkinson’s symptoms while avoiding side effects.

One problem with oral Parkinson’s drugs is that levels of the drugs can vary substantially from hour to hour depending how often the drugs are taken and how quickly they are cleared from the body.

By using a patch, patients can obtain a “steady state” of a drug, said the study’s lead author, Karen Blindauer, an assistant professor of neurology and director of the movement disorders program at the Medical College of Wisconsin in Milwaukee.

That’s important because if drug levels are too high, they can cause involuntary twitching or jerking; and if levels are too low, symptoms can worsen, she said.

In addition, it is hoped that applying a patch once a day will help patients more closely comply with their medication regimen, Blindauer said.

“It’s easier to take the (patch) medication compared to if you have to take medication three or four times a day,” Blindauer said.

Parkinson’s is caused by the loss of brain cells in the midbrain region known as the substantia nigra. Those brain cells produce the neurotransmitter dopamine. Without adequate dopamine levels, neurons can fire out of control, resulting in a lack of control of movement.

The most common symptoms are trembling; rigidity in the arms, legs and trunk; slowness of movement such as while walking; and a lack of balance and coordination.

While there is no cure for the disease, several oral medications can help control symptoms and most patients can maintain a high level of daily function throughout their lives, according to the National Parkinson Foundation.

About 1.5 million Americans have the disease, which tends to be more common among people older than 60, according to the foundation.

Dosing of drugs long has been a problem for Parkinson’s patients, said Erwin Montgomery, a professor of neurology and director of the movement disorders program at the University of Wisconsin-Madison.

“With a lot of (oral) medications, they just go up and down in the bloodstream too quickly,” he said.

It is believed that the variation in drug levels also contributes to motor complications and a weakening of the drugs’ effectiveness.

Earlier this year, Titan Pharmaceuticals, in a National Institutes of Health-sponsored study, reported promising results from a monkey trial using a device that is implanted under the skin to release a Parkinson’s drug over a period of six months.

Time-released oral medications also have been tried, but even those do not produce perfect results, Montgomery said.

The idea of a patch has some potential advantages, he said.

“We can bypass the mouth and stomach by applying a patch,” he said. “It does give us other options.”

However, Montgomery said, a potential disadvantage of a patch is that it makes it more difficult to regulate drug levels throughout the day, which sometimes is necessary.

For instance, some patients may take a pill every hour while others take one every eight hours, he said. And those intervals can change over periods as short as six months to a year.

“You really are at the mercy of the time control of the patch,” he said.

Eventually, a patch might be found to work best in combination with an oral medication, Montgomery said.

The new study, which involved 242 patients, appeared in the December issue of the Archives of Neurology. It was funded by Schwarz Pharma Inc., the drug’s maker.