Antioxidation Medication for Noise-induced Hearing Loss

Overview

This study will examine whether oral intake of 1200mg N-Acetylcysteine/day will prevent temporary threshold shift in hearing among workers exposed to noise

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: Randomized
    • Intervention Model: Crossover Assignment
    • Primary Purpose: Prevention
    • Masking: Double (Participant, Outcomes Assessor)
  • Study Primary Completion Date: January 2008

Detailed Description

Both genetic and environmental factors contribute to noise-induced hearing loss (NIHL). The cellular antioxidant system appears to protect cochlear hair cells from oxidative stress due to noise. Previous animal studies showed protective effects of anti-oxidant medicines against NIHL.The objective of this study is to test the hypothesis that preventive medication of antioxidation is related to susceptibility to NIHL. The 53 noise-exposed workers from steel industries in Taiwan will be recruited, and divided into N-Acetylcysteine (NAC)(Acetine, 1200mg/day) group and placebo one. The duration of medication is 2 weeks initially. After washout for 2 weeks, the kinds of medications in these 2 groups will be crossover and used for 2 weeks. Firstly, questionnaires interview about noise exposure, smoking, alcohol drinking, drug habit history and calculation of Body Mass Index (BMI) will be done. The following methods would be performed individually after medication. With detailed local examination with otoscope, these subjects receive hearing tests by pure-tone audiometry (PTA) and distortion product otoacoustic emissions (DPOAE) before and after their daily works. The possible confounding factors including background noise, solvent, heavy metals, carbon monoxide and temperature in the workplaces will be assessed. The amount of noise exposure is evaluated by personal dosimeter. Early morning, Blood samples will be collected. Deletion polymorphisms in the Glutathione S-transferase (GST)T1 and GSTM1 genes will be determined. Statistical analysis will be performed to evaluate the relation between intake of anti-oxidant medicine and noise-induced temporal threshold shift (TTS). The expected results of this study are to determine whether anti-oxidant supplements protect workers from noise-induced TTS. We anticipate that these human studies might help elucidate the relative importance of anti-oxidant enzymes as risk factors for NIHL.

Interventions

  • Drug: N-acetylcysteine (NAC)
    • 600mg twice daily for 2 weeks
  • Drug: glucose
    • 1 gm glucose capsule

Arms, Groups and Cohorts

  • Experimental: Acetin
  • Placebo Comparator: Glucose

Clinical Trial Outcome Measures

Primary Measures

  • Temporary Threshold Shift Measurement by Pure Tone Audiometry (A Total of Four Hearing Assessments Were Completed for Each Formulation Period on the 1st Day Pre- and Post-shift, and the 14th Day Pre- and Post-shift)
    • Time Frame: A total of four hearing assessments were completed for each formulation period on the 1st day pre- and post-shift, and the 14th day pre- and post-shift
    • The hearing threshold level (HL) at high frequency (HF) by pure-tone audiometry (PTA) was defined as the average of HLs at 3k,4k,6kHz for each ear examined. A total of four hearing assessments by PTA were completed for each formulation period on the 1st day pre- and post-shift, and the 14th day pre- and post-shift. The amount of temporary threshold change was calculated by subtracting the pre-shift hearing threshold from the post-shift hearing threshold at each frequency.

Secondary Measures

  • Temporary Threshold Changes Measurement by Distortion Product Otoacoustic Emissions (DPOAE) (A Total of Four Hearing Assessments Were Completed for Each Formulation Period on the 1st Day Pre- and Post-shift, and the 14th Day Pre- and Post-shift)
    • Time Frame: A total of four hearing assessments were completed for each formulation period on the 1st day pre- and post-shift, and the 14th day pre- and post-shift
    • Distortion product otoacoustic emissions (DPOAE) is an objective measure to assess the cochlear changes. DPOAE response threshold at high frequency (HF) was defined as the average of response levels (dB SPL) at 3k,4k,6kHz for each ear examined. A total of four hearing assessments by DPOAE were completed for each formulation period on the 1st day pre- and post-shift, and the 14th day pre- and post-shift. The amount of DPOAE temporary threshold change was calculated by subtracting the pre-shift DPOAE response threshold from the post-shift DPOAE response threshold at each frequency.

Participating in This Clinical Trial

Inclusion Criteria

  • workers in steel industry – known exposure to noise at work Exclusion Criteria:

  • ever diagnosed as having diabetes mellitus – fasting glucose of 120 or greater

Gender Eligibility: Male

Minimum Age: 25 Years

Maximum Age: 65 Years

Are Healthy Volunteers Accepted: Accepts Healthy Volunteers

Investigator Details

  • Lead Sponsor
    • National Taiwan University Hospital
  • Collaborator
    • Institute of Occupational Safety and Health, Taiwan
  • Provider of Information About this Clinical Study
    • Dr. Yue-Liang Guo, National Taiwan University
  • Overall Official(s)
    • Yue-Liang L Guo, MD, MPH, PHD, Principal Investigator, National Taiwan University Hospital
    • Tung-Sheng Shih, PHD, Study Director, Institute of Occupational Safety and Health, Taiwan

References

Coleman JK, Kopke RD, Liu J, Ge X, Harper EA, Jones GE, Cater TL, Jackson RL. Pharmacological rescue of noise induced hearing loss using N-acetylcysteine and acetyl-L-carnitine. Hear Res. 2007 Apr;226(1-2):104-13. doi: 10.1016/j.heares.2006.08.008. Epub 2006 Oct 4.

Kopke R, Bielefeld E, Liu J, Zheng J, Jackson R, Henderson D, Coleman JK. Prevention of impulse noise-induced hearing loss with antioxidants. Acta Otolaryngol. 2005 Mar;125(3):235-43. doi: 10.1080/00016480410023038.

Duan M, Qiu J, Laurell G, Olofsson A, Counter SA, Borg E. Dose and time-dependent protection of the antioxidant N-L-acetylcysteine against impulse noise trauma. Hear Res. 2004 Jun;192(1-2):1-9. doi: 10.1016/j.heares.2004.02.005.

Kopke RD, Jackson RL, Coleman JK, Liu J, Bielefeld EC, Balough BJ. NAC for noise: from the bench top to the clinic. Hear Res. 2007 Apr;226(1-2):114-25. doi: 10.1016/j.heares.2006.10.008. Epub 2006 Dec 20.

Clinical trials entries are delivered from the US National Institutes of Health and are not reviewed separately by this site. Please see the identifier information above for retrieving further details from the government database.

At TrialBulletin.com, we keep tabs on over 200,000 clinical trials in the US and abroad, using medical data supplied directly by the US National Institutes of Health. Please see the About and Contact page for details.