Antioxidation Medication for Noise-induced Hearing Loss

National Taiwan University

Status and phase: Completed; Phase 2

Conditions: Hearing Loss

Treatments: Drug: N-acetylcysteine (NAC); Drug: glucose

Study type: Interventional

Funder types: Other

Identifiers

NCT00552786

200704018M

Details and patient eligibility

About

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

Full 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.

Enrollment: 53 patients

Sex: Male

Ages: 25 to 65 years old

Volunteers: Accepts Healthy Volunteers

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

Trial design

Primary purpose: Prevention

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: Double Blind

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53 participants in 2 patient groups, including a placebo group

Acetin

Experimental group

Treatment:

Drug: N-acetylcysteine (NAC)

Glucose

Placebo Comparator group

Treatment:

Drug: glucose