THE CASE
Since 2005 there has been sporadic evidence that the use of Viagra (sildenafil) may cause blindness in a very small proportion of the men taking it. "Viagra blindness" is apparently real enough for some law firms in the US to specialise in this litigation - always a good test.
The probability of a Viagra - blindness link was confirmed in early 2005 when Dr Howard Pomeranz, director of neuro-ophthalmology at the University of Minnesota Medical School published evidence linking Viagra to nonarteritic ischemic optic neuropathy (NAION). Usually affecting one eye, NAION can be temporary or permanent. Of the 42 reports of blindness in the study, 38 of them have been made in regard to Viagra blindness and the other four in regard to the very similar drug cheap cialis (tadalafil).
Health Canada has issued an advisory regarding the three erectile dysfunction drugs Viagra (sildenafil), cialis (tadalafil) and Levitra (vardenafil), alerting patients to “seek immediate medical attention” if they experience sudden vision loss or have other vision-related problems associated with taking these medications.
In the United States the FDA issued this alert in 2005:
In Australia the official patient information on Viagra (the Consumer Medical Information or CMI) states:
And there are similar warnings in the Cialis and Levitra CMIs.
The Australian Therapeutic Goods Administration (TGA) does not carry any warnings about NAION with these erectile dysfunction drugs.
More recently (18 October 2007) there is a worrying report that these drugs may also cause hearing loss:
There is still no mention in any the Australian CMIs about hearing loss associated with the erectile dysfunction drugs.
MY VERDICT
As I have noted many times our TGA is very slow to react to potential problems within it's ambit. Recent lapses have concerned Zolpidem (Stilnox or Ambien), infant cough preparations, biphosphonates and varenicline (Chantix or Champix).
Since 2005 there has been sporadic evidence that the use of Viagra (sildenafil) may cause blindness in a very small proportion of the men taking it. "Viagra blindness" is apparently real enough for some law firms in the US to specialise in this litigation - always a good test.
The probability of a Viagra - blindness link was confirmed in early 2005 when Dr Howard Pomeranz, director of neuro-ophthalmology at the University of Minnesota Medical School published evidence linking Viagra to nonarteritic ischemic optic neuropathy (NAION). Usually affecting one eye, NAION can be temporary or permanent. Of the 42 reports of blindness in the study, 38 of them have been made in regard to Viagra blindness and the other four in regard to the very similar drug cheap cialis (tadalafil).
Health Canada has issued an advisory regarding the three erectile dysfunction drugs Viagra (sildenafil), cialis (tadalafil) and Levitra (vardenafil), alerting patients to “seek immediate medical attention” if they experience sudden vision loss or have other vision-related problems associated with taking these medications.
In the United States the FDA issued this alert in 2005:
"FDA ALERT [7/2005]: A small number of men have lost eyesight in one eye some time after taking Levitra, Viagra, or Cialis. This type of vision loss is called non-arteritic anterior ischemic optic neuropathy (NAION). NAION causes a sudden loss of eyesight because blood flow is blocked to the optic nerve.
We do not know at this time if Levitra, Viagra, or Cialis cause NAION. NAION also happens in men who do not take these medicines."
In Australia the official patient information on Viagra (the Consumer Medical Information or CMI) states:
"Rarely men have lost eyesight some time after taking drugs to treat erectile dysfunction (known as impotence). It is not known at this time if Viagra causes this. If you lose eyesight in one or more eyes, seek medical attention urgently."
And there are similar warnings in the Cialis and Levitra CMIs.
The Australian Therapeutic Goods Administration (TGA) does not carry any warnings about NAION with these erectile dysfunction drugs.
More recently (18 October 2007) there is a worrying report that these drugs may also cause hearing loss:
"FDA informed healthcare professionals of reports of sudden decreases or loss of hearing following the use of PDE5 inhibitors Viagra, Levitra, Cialis for the treatment of erectile dysfunction, and Revatio for the treatment of pulmonary arterial hypertension. In some cases, the sudden hearing loss was accompanied by tinnitus and dizziness. Medical follow-up on these reports was often limited which makes it difficult to determine if the loss of hearing was related to the use of one of the drugs, an underlying medical condition or other risk factors for hearing loss, a combination of these factors or other factors."The US drug information was modified in November 2007 to include reference to this potential hearing loss.
There is still no mention in any the Australian CMIs about hearing loss associated with the erectile dysfunction drugs.
MY VERDICT
As I have noted many times our TGA is very slow to react to potential problems within it's ambit. Recent lapses have concerned Zolpidem (Stilnox or Ambien), infant cough preparations, biphosphonates and varenicline (Chantix or Champix).
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