This takes us back a few years to a time when stories began to surface about adverse side effects to the use of drugs used to treat erectile dysfunction. Men had begun to report changes to their eyesight. One or two men apparently lost their sight for short periods of time. On many occasions when side effects are reported under the Postmarketing Surveillance Program, the FDA does not react immediately. Sometimes, it does not react at all. Without going into the politics of its role, some critics suggest the FDA is in the pocket of the pharmaceutical industry and would never react to reports of side effects unless the evidence is too public and overwhelming to ignore. That’s what made it all the more surprising when the FDA decided to apply a watered down version of the precautionary principle to erectile dysfunction drugs. Just so we all understand, the precautionary principle says you pull a product off the market until it is proved safe. Since proving the negative is difficult, this can mean the product is off the market for a long time. With erectile dysfunction drugs, we are talking about retail sales in excess of one billion dollars in 2008. You do not mess with this market by shutting it down. The most you can do is change the label to warn users of potential dangers.
In July, 2005, the FDA issued a notice acknowledging rare reports of eye problems. The notice did not accept there was evidence of a link between the drugs and the vision problems. It simply advised men affected to seek emergency aid if the rare event affected them. From a scientific point of view, there is a strong likelihood of a link. These drugs target PDE5 in the body. The relevant arteries in the eye are controlled by PDE6. The drug may not be completely specific in all bodies and the effect on PDE5 may shade into PDE6. That said, the pharmaceutical industry had a marketing problem. Even though everyone acknowledged these were extraordinarily rare events, the release of the notice by the FDA did cause some alarm. The industry therefore commissioned some research which was published this year in the Archives of Ophthalmology. It’s good news. Some 250 men men with good eyesight and erectile dysfunction were recruited and given various dosages of the drugs, one pill per day for six months. Their vision was routinely monitored throughout the trial period. There were no significant differences found between their sight before and after the period. There was no measurable effect of any kind in any of the men (except their erections, of course).
One word of caution. To be able to generalize from one sample to the population at large, there should be more men included in the trial. Only 250 men is not statistically significant. That said, this is a detailed study and the results are encouraging. Viagra has not been given an absolutely clean bill of health, but this comes close. If the industry can be persuaded to recruit a sufficient number for the next trial, we can arrive at a definitive result. While we wait, buy viagra with (almost) complete confidence. There is no evidence anyone has ever lost their sight because of this drug.