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MONDAY, APRIL 7, 2008
Contact: Donna Krupa
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dkrupa@the-aps.org
For Some Who Have Lost
Their Sense Of Smell, A Once Popular Asthma Drug Could Be Just What The
Doctor Ordered
New
study finds that treatment with theophylline improves smell function when
biochemistry is the culprit
SAN DIEGO, CA – Despite the fact that
millions of Americans are believed to have lost their sense of smell (hyposmia),
no effective method exists to treat many of these people. That is due in
part to the fact that the causes of smell loss are varied and complex,
ranging from chronic allergies, viral infection, head injury, or no apparent
reason at all. Some seven percent of Americans have lost their sense of
smell and with it their ability to enjoy the fragrance of flowers, foods and
beverages. For individuals whose smell loss relates to the biochemistry of two
common proteins, there is some good news. A team of researchers has found
that a drug used long ago to help asthmatics can benefit some with smell
loss.
The Study
The results are contained in a study entitled
Effective Treatment of Smell Loss With Theophylline. It was
conducted by Robert I. Henkin, Irina Velicu and Loren Schmidt all of the
Taste and Smell Clinic, Center for Molecular Nutritional Sensory Disorders,
Washington, DC. Dr. Henkin will present his team’s findings at the 121st
annual meeting of the American Physiological Society (APS;
www.the-APS.org/press), part of the Experimental Biology 2008 scientific
conference.
A total of 369 individuals were enrolled in the study.
Of the total, 314 had smell loss and 55 did not; 169 were female and 145
were male. The participants were 53 years of age ± 1 year. Smell loss was
measured using standard testing procedures to determine the type, degree and
character of smell loss. These included objective smell function
(psychophysical) and subjective (quantitative evaluation of smell loss)
methods. Blood measures and smell function were evaluated regularly
throughout the study.
The researchers had previously discovered that
decreased levels of two proteins – cyclic AMP (cAMP) and cyclic GMP (cGMP) –
in nasal mucus inhibited growth and development of olfactory receptor cells
and thus caused smell loss. For this reason, patients consumed 200, 400 or
600 mg of theophylline (correlated to blood levels) for a period of 2-6
months.
The drug theophylline is a generalized
phosphodiesterase inhibitor. Physicians have determined that the drug is a
generalized inhibitor which means it causes certain chemicals like cAMP and
cGMP to increase. Thus, the higher the levels of cAMP the greater the
ability to smell. This is true to a lesser extent for cGMP. It had been used
widely in the l940s and 1950s for the treatment of asthma and has been shown
to restore the biochemical problems associated with smell loss in recent
years. It has not, however, been approved by the FDA for this purpose.
Results
At the end of the study the researchers found that:
v
Psychophysical measurements showed that smell function had
increased for more than 70 percent of the participants.
v
Subjective measurements showed an increase in smelling ability
for 47 percent of the participants.
v
No correlation in theophylline blood levels changes were
evident between those whose smell loss improved and those whose smell level
did not improve.
v
There were no significant differences in improvement based on
gender or age.
v
When patients improved and stayed on the drug they continued
to improve. Conversely, if they improved their ability to smell then stopped
the drug they lost the gains they had made in their ability to smell.
Conclusion
According to Dr. Henkin, “It is well known that
millions of Americans have smell loss. It is less well known that many of
these patients have lower than normal levels of cAMP and cGMP and that
theophylline is useful to them since it increases the proteins in the mucus
levels of their nasal passages.” He continued, “These findings do not relate
to all patients with smell loss but to the many who have this biochemical
abnormality. In a similar vein, treatment of patients with high cholesterol
with cholesterol lowering agents is useful in treatment of heart disease,
but there are many causes of heart disease besides elevated cholesterol.”
A
screening test for those with biochemistry-based smell loss is at:
www.tasteandsmell.com.
*****
Physiology
is the study of how molecules, cells, tissues and organs function to create
health or disease. The American Physiological Society (APS;
www.The-APS.org/press) has been an integral part of this discovery
process since it was established in 1887.
# # #
NOTE TO EDITORS: The APS annual meeting is part
of the Experimental Biology 2008 (EB ’08) gathering and will be held April
5-9, 2008 at the San Diego, CA Convention Center. To schedule an interview
with Dr. Henkin please contact Donna Krupa at 301.634.7209 (office),
703.967.2751 (cell) or
DKrupa@the-APS.org.
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