Amiodarone is typically used to correct irregular heart beats to normal rhythm in cardiac patients. Despite its effectiveness, the medication is known to have serious potential side effects ranging from liver toxicity to lung and heart toxicity. Thus, doctors must be vigilant in monitoring patients taking amiodarone with liver enzyme measurements, thyroid and pulmonary function tests, electrocardiograms, and other tests. Since development of toxicity appears to be dependent on the dose and length of time the patient takes amiodarone, better outpatient monitoring could improve the drug's safety, suggests a study supported in part by the Agency for Healthcare Research and Quality (HS11169 and HS11534).
Researchers from Harvard University, Brigham and Women's Hospital, and the University of Toronto found that the majority of patients visited their provider regularly but received only minimum testing, perhaps due to the complexity of monitoring recommendations. After evaluating criteria for monitoring outpatient amiodarone therapy in a review of research studies from 1966 through 2000, the researchers developed a four-stage model of medication monitoring. They retrospectively reviewed the charts of 99 outpatients at one institution who received amiodarone therapy for 1 year to assess monitoring practices.
About 70 percent of the recommended monitoring criteria were satisfied for all patients, but only 9 percent of patients received all of the recommended monitoring. Monitoring practices varied at all four stages of the monitoring model. Overall, 52 percent of patients received minimum baseline evaluations; 22 percent underwent ongoing surveillance with clinical exams and laboratory tests; 75 percent had appropriate responses to abnormal surveillance results, such as altered dosage; and 71 percent had timely followup visits. Also, 8 percent of patients had nine amiodarone-related adverse drug events, of which three were judged to be preventable.
See "Monitoring amiodarone's toxicities: Recommendations, evidence, and clinical practice," by Henry Thomas Stelfox, M.D., Sofia B. Ahmed, M.D., Julie Fiskio, and David W. Bates, M.D., M.S.C., in Clinical Pharmacology & Therapeutics 75, pp. 110-122, 2004.