Potential for Conflict of Interest in the Evaluation of Suspected Adverse Drug Reactions

CONTEXT: In recent years, US patients have increasingly been the first to receive new medications, some of which are subsequently discovered to have suspected adverse drug reactions (SADRs). As a result, the challenge of early detection has largely shifted to the US postmarketing systems. OBJECTIVE: To review the association between the use of cerivastatin sodium and the risk of rhabdomyolysis in an effort to illustrate the operation and limitations of the current US postmarketing safety-surveillance system. DATA SOURCES AND SELECTION: For the published literature, we used previous reviews and MEDLINE searches from all years through 2003. For the unpublished literature, we used internal company documents that have become part of the public record during a trial in Nueces County, Texas. DATA SYNTHESIS: In the published literature, cerivastatin was associated with much larger risks of rhabdomyolysis than other statins. Although only a small percentage of cerivastatin users also took gemfibrozil, approximately half of the case reports of rhabdomyolysis occurred in users of this combination therapy, and a cerivastatin-gemfibrozil interaction was supported by the results of a 3-day pharmacokinetic study. In internal company documents, multiple case reports suggested a drug-drug interaction within approximately 100 days of the launch in 1998; however, the company did not add a contraindication about the concomitant use of cerivastatin and gemfibrozil to the package insert for more than 18 months. Unpublished data available in July 1999 also suggested an increased risk of rhabdomyolysis associated with high doses of cerivastatin monotherapy. In late 1999 and early 2000, company scientists conducted high-quality analyses of the US Food and Drug Administration adverse event reporting system data. These analyses suggested that compared with atorvastatin calcium, cerivastatin monotherapy substantially increased the risk of rhabdomyolysis. To our knowledge, these findings were not disseminated or published. The company continued to conduct safety studies, some of them inadequately designed to assess the risk of rhabdomyolysis, until cerivastatin was removed from the market in August 2001. CONCLUSIONS: Despite limitations of the available data, the asymmetry between the information available to the company and the information available to patients and physicians seems striking. A subjective element is present in the effort to infer whether or not the occurrence of untoward outcomes in users of a particular drug was actually the consequence of the use of that drug, and, under the current system, a pharmaceutical company's appraisal of SADRs may be influenced by economic considerations. Such an appraisal would best be made by an independent group. The US Congress should mandate and provide adequate support for independent reviews and analysis of postmarketing data.