Vitamin Supplements Could Prevent Drug-induced Hearing Loss

The drug gentamicin provides an effective treatment for those suffering from bacterial infections resistant to other antibiotics, but the medication can cause hearing loss.

During a recent study published in the Journal of the Association for Research in Otalyrngology, University of Florida researchers discovered a dietary supplement that shows promise in protecting against drug-induced hearing loss when taken during gentamicin treatment.

Belonging to a class of antibiotics known as aminoglycosides, gentamicin is used to treat infections resistant to other antibiotics, including penicillin or amoxicillin. Aminoglycosides are prescribed in the United States for conditions like multidrug-resistant tuberculosis or frequent lung infections experienced by patients with cystic fibrosis.

“In developing countries, aminoglycosides are often used as a first-line treatment for any infection because they are so cheap and so readily available,” Colleen Le Prell, the study’s lead investigator and an associate professor in the University of Florida College of Public Health and Health Professions’ department of speech, languages and hearing sciences told News.UFl.edu.

Studies have shown that between 2 and 25 percent of patients taking aminoglycoside antibiotics suffer from hearing loss. These estimates vary since hearing loss tends to develop slowly over weeks, so hearing tests taken during or immediately after drug treatment can miss hearing loss, according to Le Prell. Some studies use hearing tests more sensitive to the earliest effects of damage to the cells in the inner ear.

Le Prell and her colleagues tested the use of a dietary supplement containing antioxidants beta carotene and vitamins C and E, as well as the mineral magnesium, to protect against gentamicin-induced hearing loss.

Hearing loss is primarily caused by the production of free radicals, which destroy healthy inner ear cells. The antioxidant vitamins prevents the condition by scavenging free radicals and protecting against their effects.

Le Prell showed in previous studies that these vitamins prevented noise-induced hearing loss in animals and she’s currently testing the vitamin combination in human clinical trials.

“We’re enthusiastic about the use of these vitamins because of the significant safety profile that exists,” Le Prell told News.UFl.edu. “These agents are generally regarded as safe with very well-known recommended daily intakes.”

The current study’s researchers at the University of Florida and the University of Michigan gave guinea pigs a two-week course of gentamicin. Half of these guinea pigs received traditional food before and during administration of the antibiotic, while the other half received food enriched with the vitamin supplements.

The researchers tested the guinea pigs’ hearing before and up to nine weeks after antibiotic treatment by measuring their brain stem activity in response to brief sound bursts, finding that those that received the dietary supplement maintained better hearing than those that consumed the standard diet.

“The best protection was obtained at lower test frequencies and that’s important because the lower frequencies are essential for speech,” Le Prell told News.UFl.edu.

Future research will examine whether combining aminoglycosides with the vitamin mix can cause a drug interaction that affects the antibiotics’ effectiveness.

“The long term vision is clearly to see whether you can get the same benefit in human patients who are being treated with these aminoglycosides,” Le Prell told News.UFl.edu.

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