Antioxidation Medication for Noise-induced Hearing Loss

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

Detailed Description
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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.

Official Title
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Antioxidation Medication for Noise-induced Hearing Loss

Conditions
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Hearing Loss

Intervention / Treatment
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* Drug: N-acetylcysteine (NAC)
* Drug: glucose


Participation Criteria
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Eligibility Criteria
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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

Ages Eligible for Study
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Minimum Age: 25 Years
Maximum Age: 65 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Acetin<br> | Drug: N-acetylcysteine (NAC)<br>* 600mg twice daily for 2 weeks<br>* Other names: acetin (600mg);|
| Placebo Comparator: Glucose<br> | Drug: glucose<br>* 1 gm glucose capsule<br>* Other names: Sugar;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| 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) | 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. | 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 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| 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) | 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. | 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 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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noise, hearing loss, temporary threshold shift