Can Aspirin Prevent Antibiotic-Induced Deafness?

Clinical Trials in Xi’an, China, Will Show if Damage Caused by Aminoglycosides Can Be Prevented

Jochen Schacht and Suhua Sha

Salicylate — the active component of ordinary aspirin — can prevent deafness in guinea pigs exposed to a common class of antibiotics that destroy delicate hair cells in the inner ear. Such are the findings of a study published in the July, 1999, issue of Laboratory Investigation by Jochen Schacht, Ph.D., a biochemist and professor in the Otolaryngology Department, and Suhua Sha, M.D., a research associate in the Kresge Hearing Research Institute at the Medical School.

Clinical trials currently underway at Xijing Hospital, the hospital of the 4th Military Medical University in Xi’an, China, will determine whether aspirin is as effective in people as it is in guinea pigs. The trials at Xijing Hospital are being coordinated by Wei Guo Huang, professor and chair of the Department of Otolaryngology there. “These drugs are a serious problem in rural areas of developing countries, especially China and Southeast Asia, where they are widely used because they are so effective and inexpensive,” Schacht says. “All too frequently, they are the only affordable drugs available. Studies of deaf-mutism in southeastern China showed that two-thirds of the cases were caused by aminoglycosides.”

Discovered in the 1940s, aminoglycosides — which include streptomycin, gentamicin, neomycin and others — are the most widely used antibiotics in the world even though they are known to cause hearing loss and balance disorders in a significant percentage of individuals who take them.

In 1995, Schacht and his colleagues reported their discovery that gentamicin combines with iron in the body to trigger production of free radicals — unstable molecules that rip apart and damage cells. Thousands of tiny hair cells in the inner ear are especially vulnerable.

Other experiments showed that iron chelators — medications used to “soak up” excess iron in the bloodstream — protected guinea pigs from gentamicin’s ototoxic effects. One of the chelators tested was 2,3-dihydroxybenzoate or DHB. In an effort to develop a simple and clinically feasible way to prevent hair cell damage, Schacht and Sha modified the experiment using a related compound called 2-hydroxybenzoate or salicylate.

In subsequent experiments with guinea pigs receiving gentamicin, they were able to show that iron chelators, including salicylate, offer protection against damage to the hair cells of the inner ear.

The research was funded by the National Institute on Deafness & Other Communication Disorders, National Institutes of Health. The experiments were conducted at the Kresge Hearing Research Institute.

Schacht can be reached at schacht@umich.edu; Sha can be reached at shasha@umich.edu.