A Whiff of Hope for Hyposmia Victims

It was just last month that the FDA issued a warning to consumers that Zicam nasal cold remedy products might cause a loss of the sense of smell. From hyposmia (a reduced ability to smell) to anosmia (a complete loss of the ability to smell) the condition is difficult-to-impossible to treat, and affects some 20 million people in the United States alone. Now, a drug once used to treat asthma and other respiratory conditions is showing promise in restoring this precious ability to those who have lost it.

“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.

Dr. Robert 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 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,” explains Henkin. “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. 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.

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.