Characteristics of drug-associated rhabdomyolysis: analysis of 8,610 cases reported to the U.S. Food and Drug Administration.

OBJECTIVE: To describe the characteristics of cases with drug-associated rhabdomyolysis reported to the U.S. Food and Drug Administration (FDA).

METHODS: A retrospective analysis of all drug-associated rhabdomyolysis cases reported to FDA between January 2004 and December 2009 was conducted. The analyses included the number of unique cases, age, gender, body weight and proportion of fatal outcome. Time to onset from beginning of the suspected drugs and frequently reported suspected drugs were also tabulated.

RESULTS: There were 8,610 cases of drug-associated rhabdomyolysis in the database. Both case numbers and proportion of the fatal outcome appeared stable over the study period. Average age was 43.3 years old. The reported ratio of male to female was approximately 5 to 3. More than half of reported cases developed rhabdomyolysis within a month after beginning the suspected drug. Potential high risk groups for fatal outcome, such as age group younger than 10 years old and body weight group less than 50 kg were suggested. Suspected drugs for younger cases and their probable indication appear to be different from adult cases. There has been long standing controversial concern regarding an increased risk when a fibric acid derivative is added to an HMG-CoA reductase inhibitor. This study suggested that concomitant use of these two kinds of agents may be associated with a lower risk for fatal outcome, whereas renal dysfunction appeared to be associated with a higher risk for fatal outcome among the HMG-CoA reductase inhibitor-associated rhabdomyolysis cases.

CONCLUSION: The characteristics of cases of drug-associated rhabdomyolysis were described. Because of the various limitations of a spontaneous reporting-system database, the reported number should be interpreted with caution.