May 7, 2013: Overfill Needs to be Taken into Account for IV ChemotherapyMore than 1100 Canadian patients may have received lower doses of cyclophosphamide or gemcitabine than intended because of miscommunication between a supplier and several hospitals that utilized its services (http://www.cbc.ca/news/canada/story/2013/04/02/chemotherapy-dilution.html). The impact on patients is unclear but is under investigation.
The chemotherapy was part of therapeutic regimens for patients with breast and lung cancer, as well as lymphoma and leukemia. Solutions of the drugs were prepared by the supplier in ready-to-use IV bags, but the bags held a greater volume of diluent than stated on the label, a situation known as overfilling. The amount of overfilling is thought to have ranged from about 3% to about 20%. For reasons that have not yet been revealed, the supplier and the hospitals did not have a common understanding of the total amount of overfill after the chemotherapy additive was added to commercially available IV bags, which have an inherent overfill volume. Because of the inherent overfill, the final drug concentration in each prepared bag was less than if the exact amounts of drug and diluent solution had been added to an empty IV bag. Each bag contained the labelled amount of drug, but a lack of a common understanding of the final concentration led to some patients receiving a lower dose than intended.
Management of any overfill volume is perceived to be more critical for oncology medications than for other types of medications because the dosing of these drugs is highly specific to each individual patient and the type of cancer being treated. In the recently released International Medication Safety Self Assessment® (MSSA) for Oncology, developed jointly by ISMP in the United States and ISMP Canada, the use of overfill was identified as a point where safeguards may be required. Specifically, the International MSSA for Oncology states the need for “a standard process to identify the overfill volume on the pharmacy label for compounded IV chemotherapy/biotherapy solutions”. An opportunity exists to create and implement national standards for labelling containers that contain overfill volume. We would very much like to hear from front-line practitioners, hospital administrators, and others with thoughts on this problem, as we work with our partners to develop recommendations for standard labelling practices.