Viagra Use May Increase the Risk for Sudden Hearing Loss
By Nancy Fowler Larson
Medscape Medical News
May 23, 2010 — Men who have taken sildenafil (Viagra; Pfizer) are more likely to experience sudden sensorineural hearing loss, according to an study published in the May issue of the Archives of Otolaryngology–Head Neck Surgery.
More than 2 dozen recent reports have indicated an association between sudden sensorineural hearing loss and phosphodiesterase type 5 inhibitors (PDE-5is). Examples of PDE-5is include the following:
sildenafil citrate (Viagra and Revatio; Pfizer),
vardenafil (Levitra; Bayer Pharmaceuticals, Schering-Plough, and GlaxoSmithKline), and
tadalafil (Cialis; Eli Lilly).
In 2007, based on roughly 30 case reports, the FDA required manufacturers of these drugs to warn consumers of possible hearing loss. Some studies have evaluated mechanism of action to explain the potential causal association; however, deeper examinations of the possible relationship between the drugs and hearing loss have not been conducted.
"To my knowledge, no epidemiologic studies to date have evaluated the association between PDE-5i use and [hearing loss]," writes study author Gerald McGwin, PhD, from the Department of Epidemiology, School of Public Health, University of Alabama at Birmingham. "To help fill this void in the current literature, this study evaluates this relationship in a population-based sample of men in the United States."
Using logistic regression, the study compared subjects with and without hearing loss against the use of PDE-5i both before and after adjustment for possible confounding factors. The cohort consisted of 11,525 men (249,217,013 weighted), aged 40 years and older, chosen from the 2003 to 2006 Medical Expenditure Panel Survey. During a 2-year period, the participants provided information in 5 total interviews about their demographics, health, healthcare activities, and prescription medications. They also self-reported any hearing difficulty and use of hearing aids.
The results showed that the overall incidence of hearing impairment was 17.9% — a percentage that increased with age. Roughly 2% of the subjects had taken some type of PDE-5i drug, 80.3% of whom used sildenafil. Unadjusted results showed that taking PDE-5i was more than twice as common among those with hearing loss (3.0% vs 1.4%); the percentages remained nearly the same after adjustments for demographics and health factors, among other findings.
Those with hearing loss more often used PDE-5i (odds ratio [OR], 2.23; 95% confidence interval [CI], 1.36 - 3.66).
The relationship between PDE-5i drugs and hearing loss was confined to sildenafil (OR, 2.05; 95% CI, 1.23 - 3.43).
No meaningful relationship to hearing loss was seen with tadalafil or vardenafil (ORs, 1.40 [95% CI, 0.49 - 4.04] and 0.88 [95% CI, 0.35 - 2.22], respectively).
Dr. McGwin posited that the relationship between PDE-5i and hearing loss might be a result of the drugs' tendency to promote congestion of nasal erectile tissue, which can then elevate middle ear pressure.
"It has also been suggested that PDE-5i may intensify the effects of nitric oxide, which has been implicated in a number of otologic diseases, or simulate the effects via activated intracellular cyclic guanosine monophosphate (cGMP)," Dr. McGwin writes. "The PDE-5i function by blocking the degradation of cGMP, the accumulation of which induces gene expression via transcription factors by protein phosphorylation by specific kinases, which themselves have been associated with damage to cochlear hair cells."
Although tadalafil demonstrated a slight association with hearing impairment, the rise was not statistically significant. Dr. McGwin acknowledged that the limited use of tadalafil and vardenafil by participants may have prevented the study from finding their possible association with hearing impairment.
Many questions remain about PDE-5i drugs and hearing loss. Still, according to Dr. McGwin, the current findings do substantiate the use of US Food and Drug Administration warnings.
"The largely irreversible nature of [hearing loss] and its impact on quality of life underscore the need for additional research regarding the etiologic role of PDE-5i use," Dr. McGwin writes. "In the interim, it is prudent that patients using these medications, specifically sildenafil, be warned about the signs and symptoms of hearing impairment and be encouraged to seek immediate medical attention to potentially forestall permanent damage."
The study author reported that legal counsel has retained him as an expert witness in cases related to the relationship between Viagra and nonarteritic ischemic optic neuropathy. No other relevant financial relationships were disclosed.
Arch Otolaryngol Head Neck Surg. 2010;136:488-492.
