Last month, the U.S. Food and Drug Administration requested the manufacturers of propoxyphene (PXP), a pain reliever, to stop selling drugs containing the substance. PXP was introduced in 1957, under the trade name of Darvon. Various derivatives quickly followed -- Darvon Compound and Darvocet -- which added other analgesics to the parent drug. At the time of the recall, an estimated 10 million Americans took PXP-containing drugs.
By itself, PXP was not particularly effective in relieving pain. The drug did seem to have an addictive risk. Stories circulated that PXP could extend or enhance the effect of narcotics.
The recall was based upon reports that PXP could cause dangerous disturbances in heart rhythm. Critics of PXP had argued for more than 20 years that the drug was unsafe for a variety of reasons. The vote by FDA overseers of product safety was 14 to 12, reflecting the controversy surrounding the issue. The United Kingdom and European Union banned PXP sales several years earlier.
PXP joins other recently recalled drugs with suspected, cardiac side effects. Rofecoxib (Vioxx) was recalled in September 2004 despite a spirited defense by its manufacturer that the drug was safe. The recall was based upon heart problems that appeared after 18 or more months of use of the drug.
More recently, the FDA issued new warnings of cardiac risks associated with the diabetes drug rosiglitazone (Avandia). The panel evaluating this drug was deeply divided over the issue of withdrawal versus restricted use of the agent.
Pharmaceutical firms invest vast sums in developing, testing and bringing new drugs to market. Most new drugs are never approved, falling by the wayside as extensive testing progresses. Before final approval, the FDA conducts extensive review of all laboratory and clinical studies to assess the efficacy and safety of a new drug. The reviewers must depend upon the integrity of the scientists who have conducted the studies. The FDA does not have the capacity to test new drugs independently.
Serious side effects may not surface until months or years after the release of a new drug. Because many people take a number of prescription drugs simultaneously, the task of attributing an adverse reaction to one drug can be complex. One drug may affect the action of another by blocking or speeding up its disposal. The health of the patient receiving a medication is also a compounding factor. An illness may interfere with the effect and inactivation of the drug. If the patient has pre-existing heart problems, cardiac side effects of a particular drug will be difficult to detect.
The reporting of an adverse drug reaction is voluntary. Many adverse reactions go unreported. Health-care providers are ill-informed about the process of reporting. They fear hassle if they report a reaction. Years ago, I reported a suspected drug reaction and endured for almost a year harassing phone calls from the manufacturer to modify or withdraw my report.
The issue boils down to the risk versus the benefit of taking any drug.
Since our current system of monitoring drug safety seems flawed, would it not make sense to give provisional approval to each new drug? For a two-year period following approval, the new agent would be subject to tighter review and closer monitoring of potentially dangerous side effects. To achieve this goal, the FDA would need more money and manpower. Savings would be realized quickly, however, in saved lives and reduced frequencies of hospitalization for drug-related illnesses. This is a big problem that deserves fresh thinking.
E-mail Clif Cleaveland at firstname.lastname@example.org.