Although prescription drugs undergo clinical trials before they hit the market, unexpected adverse events may still occur in the general population. Therefore, FDA collects adverse event reports and looks for potential trends. In its latest surveillance report, the agency has identified 19 drugs that are associated with adverse events and, therefore, are undergoing close evaluation.

A centerpiece of the FDA's safety surveillance efforts is the Adverse Drug Event Reporting System. This computerized database is used to collect and analyze safety reports on all approved drug and therapeutic biological products. If a potential safety concern occurs, further epidemiologic studies may be performed, and, eventually, regulatory actions may be taken such as changing a drug's labeling, restricting its use, warning the public, or even removing the drug from the market.
The most recent FDA report based on Adverse Drug Event Reporting System data collected in the fourth quarter of 2008 provides a list of drugs that represents "potential signals of serious risks" or that has new safety information (Table). These potential safety issues were identified in reports filed by clinicians and patients via the agency's MedWatch program.

Table. Drugs With Potentially Serious Risks or New Safety Information

From US Department of Health & Human Services, US Food and Drug Administration. Available at: http://www.fda.gov/Drugs/GuidanceComplianceRegulatoryInformation/Surveillance/AdverseDrugEffects/ucm161063.htm.

FDA evaluation of these drugs continues, and officials stress that until a potential relationship between the drug and the risk is fully evaluated, it is not clear what causes the association. The adverse event(s) may be precipitated by concurrent disease states, coadministration of other drugs, change in patient health status, previous drug therapy, or other causes. Clinicians do not need to stop using these drugs, but they should be aware of the potential risks.
Already, the FDA has taken action on several of the drugs on the list. For example:

• Sumatriptan/naproxen. The FDA reviewed the existing boxed warning on the product label addressing myocardial infarction and concluded it was adequate;
• Testosterone gel. A May 2009 news release announced the addition of a new boxed warning that addresses potential adverse events in children and women who are accidentally exposed to testosterone gel; and
• Varenicline, bupropion. The FDA distributed a Safety Alert and Public Health Advisory concerning these smoking cessation agents. The FDA now requires that medication guides highlighting the risk of neuropsychiatric symptoms be provided to patients receiving these medications. Information for healthcare professionals, patients, family members, and caregivers is included.

The FDA recently redesigned its Website (www.fda.gov) to make drug safety information more accessible for patients and providers. There are 3 ways to search for topics on this site: an A-to-Z

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