Oral amiodarone loading dose continued for 8 months in error
A patient who had been receiving amiodarone, an antiarrhythmic, for recurrent hemodynamically unstable ventricular tachycardia (VT), was admitted to an ICU with significantly elevated serum liver enzymes. The pharmacist who completed the admission medication history discovered that the patient had been receiving amiodarone tablets at a loading dose of 400 mg per day for 8 months, which had only been intended for 4 weeks. The patient had been receiving outpatient care from several practitioners, including cardiologists, and had been hospitalized at different locations during those 8 months, all while taking the 400 mg daily loading dose of amiodarone. The overdose was not identified until the patient was admitted with hepatic toxicity.
Amiodarone is intended for use only in patients with life-threatening dysrhythmias because its use can result in significant adverse reactions. The drug has a Boxed Warning that includes hepatoxicity, which can be fatal. Amiodarone is used off-label for various ventricular and supraventricular dysrhythmias with corresponding dosing regimens. Amiodarone is unique in that, based on the indication, treatment is usually initiated with a loading dose until a therapeutic response occurs, followed by a tapered dose, and then a maintenance dose. Even though 400 mg per day can be used as a maintenance dose for VT per the package insert (http://www.ismp.org/ext/1185), this was not the intended dose for this patient's maintenance regimen. In contemporary practice, once a patient is stable, the dose may be reduced to 100 to 200 mg per day to lessen the risk of adverse reactions and toxicity. Transitions of care and multiple handoffs between providers, such as cardiologists, hospitalists and primary care providers, may contribute to the failure to identify extended loading dose errors or doses that were intended to be reevaluated for dose reduction. Poorly designed processes for medication reconciliation or breakdowns in the system in both inpatient and outpatient settings may also lead to missing this type of dosing error.
Lastly, since the dose that the patient was receiving was within the limits listed in product labeling, it may be difficult to identify that the loading dose was extended beyond the recommended duration, until significant patient harm brings attention to the matter. It is important to remember that due to amiodarone's prolonged half-life (15 to 142 days), even after the drug has been discontinued, patients may still be at risk for amiodarone toxicity.
ADC drug description leads to mannitol overdose.
A prescriber in the ED gave a verbal order for 60 g of I.V. mannitol for a patient admitted with trauma. The organization did not have profiled automated dispensing cabinets (ADCs) or pharmacist order verification in the ED, so the nurse had free access to mannitol from the ADC without pharmacist review. The drug description on the ADC screen displayed the product as "mannitol 20 g/100 mL," but the infusion bags were 500 mL and labeled "100 g/500 mL." Thinking each bag only contained 20 g, the nurse removed and administered 3 bags (300 g/1,500 mL of mannitol) to the patient when only 60 g (300 mL) should have been infused.
The organization has since updated the ADC drug description to display "mannitol 100 g/500 mL" to reflect the total amount in the container. They now provide an auxiliary label on the mannitol bags, warning that each contains a total of 100 g. They also reduced the par level (the number of bags stored) in the ADC from 3 to 1; additional bags must be requested from the pharmacy if needed. This error along with the corresponding system and process changes were shared throughout the organization. It is important to review how medications are displayed on drug selection screens, such as the electronic health record, ADC, and smart infusion pump. Concentrations should reflect the total quantity per total volume in the container, such as 100 g/500 mL. Use the profiled mode in ADCs in all areas of the hospital, including the ED, so that medications are reviewed and verified by a pharmacist prior to removal. This will prompt the removal of the appropriate number of bags from the ADC based on the order, and also allow for bedside barcode scanning, which may identify an error before it reaches a patient.
Limit the use of verbal orders to times of real emergencies. Implement additional strategies to reduce the risk of errors, such as limiting the quantity of vials, tablets, and infusion bags that are available on override.