First, do no harm pg. 3
The problem in our present day and age, says Ray, is that the rather cumbersome guidelines for ensuring safety and efficacy of drugs slowed down the process of getting drugs to market, and in the 1980s consumers and pharmaceutical companies alike began pushing for quicker approval.
The upshot, he says, is that “… to get drugs to market in a reasonable amount of time, we put them through phase I, II and III trials, but we still don’t know much about them. We know enough about a drug so that people can begin using it, but not enough about its long-term effects. So we have to keep studying it.”
Unfortunately, that is where the existing system falls short. “Following a drug once it’s on the market is a free-for-all,” he says.
Reporting the signal
The system the FDA uses for conducting post-marketing surveillance of drugs, MedWatch, relies on doctors, nurses and pharmacists to report safety concerns, based on suspected serious adverse reactions they have observed. There are two instances in which this type of reporting system works well—if a problem arises that is extreme or unusual, or if a problem appears within a large proportion of consumers.
In the first instance, a drug may produce such an unusual, distinctive form of toxicity that physicians immediately take notice, such as the idiosyncratic birth defects among pregnant users of thalidomide.
Another example is the drug-induced arrhythmias discovered in consumers of the antihistamine Seldane.
“Seldane was given to millions of patients before the potential for severe drug reactions causing life-threatening arrhythmias was recognized,” says Dan M. Roden, M.D., who directs the John A. Oates Institute for Experimental Therapeutics at Vanderbilt. “The adverse effects only occurred in patients who were using Seldane in combination with other drugs.”
Although the arrhythmias caused by Seldane toxicity were so rare that they were hard to detect, their uniquely abnormal patterns enabled physicians to eventually track similar peculiar rhythms among patients and trace them back to use of the drug. Seldane was withdrawn from the market in 1997.
A much more difficult problem to identify, says Roden, is drug toxicity that leads to an increase in a common event, such as heart attack or stroke among the elderly. The situation becomes even more complex if patients have been taking a medication for weeks, months or years before they suddenly have adverse reactions. Physicians may have no reason to suspect the drug.
“Suppose a drug increases colon cancer by 20 percent. Unless they do a prospective clinical trail, we will never know,” Roden says. “My personal bias is that these kinds of unrecognized drug actions are all around us.”
A key to determining both the benefits and detriments of a particular drug is finding the first “signal”– the indication of some unanticipated side effect—and reporting that signal to the FDA.
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