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Danger of drug patches often overlooked

August 27, 2007|Ricardo Alonso-Zaldivar | Times Staff Writer

washington -- Army Master Sgt. Harold Kinamon entered a military hospital in Ohio for routine respiratory surgery to help him sleep better. The operation, in October 2005, progressed smoothly. He went home with nothing more than a raw throat and a painkiller contained in an adhesive patch on his skin.

That night, Kinamon, 41, died in his sleep -- killed by an overdose of the drug delivered through the patch.

What made his death even more tragic was that the dangers of using skin patches to administer the particular painkiller he received, an opiumlike drug called fentanyl, were clearly understood at the time. Only three months earlier, the Food and Drug Administration -- responding to a number of similar deaths -- had issued a strong warning: Though beneficial under appropriate conditions, fentanyl patches should be used with great caution, and not for postoperative pain relief.

Kinamon's death reflects more than an individual misfortune. Healthcare providers nationwide are still not getting the message as fentanyl patches continue to be implicated in scores of deaths.

Failure to solve the problem is all the more serious because the use of patches is spreading to other drugs, including other painkillers, contraceptives and medications for children with attention deficit disorder. Moreover, a new generation of high-tech patches is expected to make many more drugs available in patch form.

The benefits of patches have been accompanied by problems, replicating a pattern common to many medical advances: Breakthroughs often come with risks and downsides that may not be fully recognized until later.

Drug safety experts are urging the FDA to reexamine the issue of medicinal patches. One primary problem seems to be how to get the right dose of a drug through a patch for different patients under differing conditions.

Patches are "a neat way of delivering drugs," but they are not an unalloyed blessing, said Dr. Curt D. Furberg of the Wake Forest University medical school.

The appeal of the patches is clear: They solve a host of problems with more traditional methods of administering medications. Unlike injections, they don't hurt. Unlike pills, they don't have to be swallowed. They resolve the common problem of patients not taking drugs in the right amount at the prescribed intervals. And their medicine enters the bloodstream directly, rather than via the stomach.

Those advantages are real, medical experts say, but they are not the whole story.

Sales of Ortho Evra, the first birth-control patch, plunged last year after the FDA cautioned that it exposed women to higher levels of a hormone linked to dangerous blood clots than do oral contraceptives.

With pills, the drug level spikes after consumption, dropping as the time for the next dose approaches. Patches maintain a steadier level, but, over time, this can lead to higher total exposure to the drug. That can cause problems, and the trade-offs are not well understood, experts say.

"What is the corresponding patch level that would be equivalent to oral drugs?" Furberg asked. "People use different formulas and there is disagreement."

The Daytrana patch for attention deficit disorder recently ran into problems. Opening the patch and getting it to stick was difficult. (The maker says the adhesion problem has been fixed.) And the medication can irritate the skin, causing welts. The FDA is investigating.

The effect of any patch can vary considerably from patient to patient. "Some people may not get enough of the drug, which defeats the purpose of taking it. And some may get too much . . . which is going to hurt some people," Furberg said.

For instance, heat affects the rate at which the skin absorbs a drug. Sunbathing, a hot shower or exercise can trigger an overdose.

Also, some people have thicker skin, which is more resistant to absorbing a drug. Speed of absorption can vary by a factor of about three, which can complicate finding the right dosage.

Another problem is psychological: Patients and medical professionals have a tendency to see patches as benign devices akin to a bandage. It's easy to forget the powerful, potentially dangerous drug within.

"Patches are not innocuous," said Kenneth Sloan, a medicinal chemist at the University of Florida whose research has shown wide variations in how quickly individuals absorb drugs through the skin. "One patch does not fit all."

That's why the FDA said in July 2005 that in the case of fentanyl, patches should be prescribed at the lowest practicable dose, should not be used to treat short-term pain or pain after an operation, and should only be used by patients already established on opioid drugs.

Patients and caregivers must be fully informed about safety, the FDA said.

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