FRIDAY, July 10 (HealthDay News) -- A drug once used to treat
asthma and other respiratory conditions shows promise in restoring a sense
of smell to those who have lost that precious ability.

"More work needs to be done but, for patients for whom other treatments
don't work, this may be an option worth trying," said Dr. Ronald
Kuppersmith, clinical assistant professor of surgery at Texas A&M
Health Science Center College of Medicine and president-elect of the
American Academy of Otolaryngology-Head and Neck Surgery.

The drug, theophylline, does have side effects and is now out of vogue
for asthma and related disorders, said Kuppersmith, who was not involved
in the study.

According to background information in the article, about 20 million
people in the United States have some degree of hyposmia, or loss of the
sense of smell, affecting their ability to enjoy the flavor of artichokes
and the fragrance of azaleas.

"There's a whole spectrum from having mild changes in your sense of
smell to complete loss," Kuppersmith said. "It can be very frustrating for
the patient, but also for the physician. A lot of people can't enjoy
coffee because they can't smell it. They lose weight. They can't smell
flowers."

Any number of things can cause the problem. "The most common causes are
viruses, head trauma, severe allergies or some kind of anatomic
obstruction in the nose or nasal polyps," Kuppersmith explained.

In June, U.S. health officials warned consumers to stop using Zicam
nasal cold remedy products because they can cause the loss of a sense of
smell.

According to Dr. Robert Henkin, lead author of the study that appears
in the June issue of the American Journal of the Medical Sciences,
there are few effective treatments out there.

Henkin, director of the Center for Molecular Nutrition and Sensory
Disorders in Washington, D.C., and his colleagues had previously
discovered that people with hyposmia had reduced levels of cyclic
nucleotides in their saliva and nasal mucous, and that treatment with
theophylline had increased levels of this growth factor and restored some
of the sense of smell.

These cyclic nucleotides are growth factors for olfactory (related to
smell) and other neural tissues.

"I had earlier done the first total protein analysis of saliva and
mucous to learn what was in there, and found these growth factors and
found that people who couldn't smell had diminished levels of the
factors," Henkin explained. "Theophylline, in a sense, inhibits the
breakdown of growth factors so more are going to stick around."

Henkin and his team have now confirmed the efficacy of theophylline in
this context in 312 patients with hyposmia over a seven-year study
period.

All of the study participants had decreased levels of growth factors
cAMP and/or cGMP, as measured in their nasal mucous.

More than half of participants said their sense of smell improved after
being treated with theophylline, while more than 20 percent said their
smell returned to normal. Larger doses of the compound and longer
treatment times resulted in greater improvements.

"People who had relatively mild or moderate disease seemed to respond
to this treatment but those patients tend to respond to other treatments
as well," Kuppersmith said. "Most of those who had severe or complete loss
of sense of smell didn't respond, which is typical of a lot of treatments
out there."

Also, he said, "some people who lose their sense of smell get better
anyway, especially if they have mild cases, so they would have gotten
better with or without treatment."

But, Kuppersmith added, for certain patients this might be a helpful
option if other things don't work.

Side effects of theophylline were minimal, the researchers noted, but
can include jitteriness, nervousness and difficulty falling asleep.

Henkin said that the findings need to be verified with a clinical
trial. His team is now looking at ways to deliver the drug intranasally
(this study involved pills). He also needs a drug company to develop and
market the medication, should it continue to prove useful.

More information

The Sense of Smell Institute has more on hyposmia.