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NAC is useful in preventing damage to hearing caused by antibiotic drugs

Dec 26, 2007

Aminoglycoside antibiotics cause toxicity to the kidneys that can reverse after termination of drug use, and permanent damage to hearing (ototoxicity). Because of their toxicity, and because they work against serious infections these antibiotics are reserved for severe infections by specific-dangerous bacteria. Free radical damage generated by the antibiotics contributes to both types of toxicity.

In this study 53 dialysis patients with blood infections (bacteremia) caused by the catheter used in dialysis were scheduled for treatment with the antibiotic gentamicin; an aminoglycoside antibiotic known for its ability to damage hearing. The patients were split into two groups - one of which received the supplement NAC along with the antibiotic. There hearing was monitored using standard pure tone audiograms over a range of frequencies. The hearing test was given before antibiotic therapy and again at one week after and at six weeks after completing antibiotic therapy ( gentamycin therapy typically lasted for 15 days).

At one week after and six weeks after cessation of antibiotic therapy significantly fewer of the patients protected by NAC suffered toxicity to their hearing than those in the group not given NAC. The patients not protected with NAC did not just suffer with simple damage to hearing but more frequently suffered it in both ears. The study is published in the August 2007 issue of the American journal Kidney International and is discussed in the September 2007 issue of the British journal Nature Clinical Practice Nephrology.

Some great studies on hearing and nutrients

  • Researchers in the Department of Otolaryngology, Albert Einstein College of Medicine exposed auditory neurons (nerve cells involved with hearing) to the drug Cisplatin; a drug used to treat cancer that is ototoxic. If the cells were pretreated with the powerful antioxidant NAC they were strongly protected from the chemotherapeutic drug. In a second study the hair cells of the cochlea were also protected; these hair cells sense sound and produce the hearing signals that are transmitted to the brain; Laryngoscope, July 2001.
  • Scientists from the Kresge Hearing Research Institute at the University of Michigan delineated mechanisms of noise-induced hearing loss in guinea pigs. The loss of cochlear hairs and auditory reactions in the brain were analyzed. Giving the animals NAC prevented damage to hearing and also to the cochlear hairs effectively; Brain research, March 21st, 2003.
  • Scientists at the Hough Ear Institute in Oklahoma City investigated the benefits of NAC and Acetyl-L-Carnitine (ALCAR), two powerful antioxidants, to the hearing apparatus. Free radicals play a significant role in the damage to hearing caused by noise. In this study chinchillas were exposed to impulse-noise; a cause of hearing loss. The animals were exposed to 155 decibels for 150 repetitions. Some of the animals were given NAC and ALCAR before and after exposure to the noise, followed by an additional two days of supplementation. Three weeks after exposure to the noise, the animals protected by the antioxidants had much greater sensitivity to sound, hearing sounds up to 30 decibels fainter than animals not protected. The NAC and ALCAR combination also protected cochlear hair cells. The results indicate a strong protective effect of ALCAR and NAC in the cochlea preventing the damage to hearing caused by noise. It is feasible that these readily available antioxidants can be used to protect hearing in humans; Acta Otolaryngologica, March 2005.
  • Note; 85 decibels is the maximum noise level that is considered safe for the unprotected ear.
      ***** Decibel levels of different noises;
    • Normal conversation - 60 decibels
    • Lawnmower, shop tools, truck traffic - 90 decibels
    • Chainsaw, snowmobile - 100 decibels
    • Concerts - 110 to 120 decibels
    • Some sporting events can achieve 130 decibels
    • Gun or jet engine - 140 decibels; noise causes pain and some hearing damage
    • Properly fitted earplugs reduce noise about 15 to 30 decibels.