May 23, 2008

Ragweed allergy trial bypasses shots

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Teresa Pradhan, L.P.N., tests a new therapy to treat ragweed allergies. (photo by Anne Rayner)

Ragweed allergy trial bypasses shots

Vanderbilt is testing a new therapy to treat ragweed allergies. (istockphoto)

Vanderbilt is testing a new therapy to treat ragweed allergies. (istockphoto)

Teresa Pradhan, L.P.N., has suffered from ragweed allergies since she was a child.

She remembers that her symptoms, which include runny nose, itchy ears and, in her case, an itchy mouth, would appear soon after school started in August and last until the first frost.

As an adult, she has tried over-the-counter medications such as antihistamines and nasal sprays. They work for a while and then her body builds up resistance, and the symptoms break through. The one thing she has not tried is allergy injections. She just doesn't like the idea of getting a needle stick every day.

When she learned that Vanderbilt's Asthma, Sinus and Allergy Program (ASAP) where she works was recruiting participants for a study of sublingual immunotherapy to treat ragweed allergies, she volunteered right away.

Vanderbilt is one of 30 centers participating in the Phase III trial to test the efficacy of placing ragweed allergenic extract under the tongue. The randomized, double-blind, placebo-controlled trial is currently recruiting adults with moderate to severe ragweed allergies to determine an effective dose range for administering the extract.

The study is tailor-made for people like Pradhan, who has worked as a nurse at ASAP for six years. She empathizes with her patients who come into the clinic looking for relief from their allergy symptoms.

“When ragweed season is here, I have to keep my windows closed and stay indoors,” she said. “On my worst day, I'm miserable. I'm sneezing; my nose is running.”

Ragweed is a prominent allergen in Nashville and one of the reasons Vanderbilt was selected as a trial site. Ragweed is present in most other parts of the country except the desert southwest and most of California. The pollen season lasts longer in Nashville because it doesn't get a hard freeze until late fall.

The basic treatment program for seasonal allergy includes medications such as antihistamines and anti-inflammatory nasal sprays. For patients who have a history of moderate to severe symptoms in whom those medicines haven't done a good job, allergy injections for ragweed and other relevant allergens are generally recommended.

“Up to 30 — 40 injections may be required during the build-up phase over a three- to six-month period,” said John Fahrenholz, M.D., assistant clinical professor of Medicine and principal investigator for ASAP.

“When adequate maintenance doses are reached, this form of immunotherapy has been shown to be highly effective and relatively safe.”

In order for the allergy injections to work over a lifetime, one needs to commit to the immunotherapy program for four to five years. In addition, a patient must go to a doctor's office to receive the injections.

“Dropout rates exceeding 50 percent are not uncommon,” Fahrenholz said.

One of the benefits of sublingual immunotherapy is that patients can administer the drops to themselves at home. While side effects can occur, prior studies of sublingual immunotherapy suggest that this form of treatment will prove safer than standard allergy shots.

“Assuming we find positive results, identify the correct dose and prove the drops work, then the main advantages would be safety and convenience,” Fahrenholz said.

This is good news for allergy sufferers like Pradhan.

“When I started working here, I didn't know anything about allergies except that I had them. I had never been to a specialist to be treated,” she said. “I want to see how sublingual works. It's easy and simple and doesn't take as much time as going in for shots.”