Improper dosing in IV bags led to diluted chemotherapy solutions

Improper dosing of chemotherapy in IV bags recently caused a problem among a group of patients in Canada, so the Institute for Safe Medication Practices (ISMP) is cautioning healthcare practitioners about chemotherapy dosing.

In August, ISMP Canada reported that more than 1,100 patients in Canada received diluted, or less potent chemotherapy doses. Larger bags of chemotherapy had been used to prepare smaller, individual doses of chemotherapy, but the overfill bags used to prepare and administer the chemotherapy were not managed correctly, according to the ISMP.

In addition, there was a misunderstanding between the pharmacy and the hospital. A group purchasing organization had contracted with a new compounding pharmacy to provide cyclophosphamide and gemcitabine solutions to hospitals. A discrepancy in labeling between the previous supplier and the new supplier on a gemcitabine preparation led a hospital pharmacist to ask the compounding pharmacy for clarification.

“The new compounding pharmacy thought each full bag of gemcitabine and cyclophosphamide contained a single dose to be administered to a single patient. However, the hospitals were using each bag as a multidose product, apportioning the medication from a single bag among several patients,” ISMP wrote in its November 14, 2013, Medication Safety Alert (Acute Care) newsletter.

In some cases, hospital staff have difficulty determining chemotherapy dosing because of the variability in overfill. Although bags or bottles of parenteral solution may be labeled to contain 25,50, 100, 250, 500, or 1,000 mL, the actual volume is larger because it contains overfill.

As a result, hospitals need to develop standardized preparation methods. “There is no single, standard method appropriate for all infusions in all hospitals, particularly given the variability in environmental conditions, staff expertise, and technology among hospitals,” ISMP wrote.

Some hospitals use the 10% rule for preparation of infusions. “The rule suggests that, if the volume of the additive medication(s) is more than 10% of the volume listed on the bulk container (without regard to overfill), the volume of the additive, and sometimes the volume of the overfill will be removed,” the ISMP wrote. “Unless starting with an empty bag (full sterile compounding), the 10% rule is often applied to all admixtures, except small volume intermittent solutions such as antibiotics or products with manufacturer-specific preparation procedures.”