Amiodarone: a postmarketing evaluation of monitoring for drug-induced toxicity

Amiodarone, an antiarrhythmic drug with predominantly class III effects, has demonstrated serious adverse drug reactions and interactions. The Departments of Pharmacy and Cardiology retrospectively evaluated the monitoring parameters at this institution. Criteria based on current literature were developed. Twenty-six patients were administered amiodarone, qualifying for entry into the audit. Of these patients, seven were excluded because their medical records were unavailable or incomplete. The 19 eligible patients were hospitalized during initiation of therapy and followed in the Outpatient Cardiology Clinic. The collected data extracted from the medical charts were compared with the following elements of the criteria selected: baseline evaluation prior to the start of therapy; monitoring for signs of pulmonary, hepatic, thyroid, cardiac, ophthalmologic, neurologic, and dermatologic toxicity; and evaluation of potential drug interactions with digoxin and warfarin-type anticoagulants. The percentage of criteria elements appropriately monitored on each patient ranged from 82 to 100 percent, with an average of 91 percent. The most frequently overlooked parameters were warning the patient of a possible photosensitivity reaction, decreasing the digoxin dose if the patient was concurrently taking amiodarone, and performing a slit-lamp examination every six months. Frequent examination of the patient's total organ system and laboratory tests, in addition to patient education, are essential to safe monitoring of amiodarone therapy.