This column was prepared by the Institute for Safe Medication Practices (ISMP), an Emergency Care Research Institute affiliate.
A pharmacy reported an incident in which a patient inadvertently received a mixture of two controlled substances (CS). The prescription was for HYDROcodone-acetaminophen, but during the filling process, a pharmacy technician mistakenly retrieved both a manufacturer’s bottle of HYDROcodone-acetaminophen and a return-to-stock (RTS) bottle of oxyCODONE-acetaminophen. The technician poured the contents of the RTS bottle and the manufacturer’s bottle onto an Eyecon counting machine. This machine uses a camera to visually count and identify incorrect solid oral dosage forms. However, according to the reporter, the tablets of both drugs look nearly identical, with very similar shapes, and thus the counting machine did not recognize that there were two different medications on the counting tray.
The technician completed the dispensing process and passed the prescription to the pharmacist for verification. Unfortunately, the pharmacist also did not recognize that the vial contained a mix of two different medications. The prescription was dispensed, and the patient began taking the medication.
The following day, the patient noticed the presence of different tablets in the vial and contacted the pharmacy. The pharmacy promptly corrected the error, provided the correct quantity of HYDROcodone-acetaminophen, and segregated the oxyCODONE-acetaminophen tablets to be returned with expired medications.
The pharmacy reported a number of factors that contributed to this event. First, the pharmacy dispensing system does not print an RTS label with a usable barcode. Instead, staff manually covers the patient’s name with a privacy label when returning a prescription vial to stock. Only the correct manufacturer’s bottle of HYDROcodone-acetaminophen tablets was scanned during the Eyecon process; the RTS vial was not. Breakdowns occurred in the manual verification process of the National Drug Code (NDC) of the RTS medication during both dispensing and verification. The pharmacy technician and pharmacist did not notice that the RTS bottle contained a different medication (and NDC). Also, it is thought that the RTS vial of oxyCODONE-acetaminophen was possibly stored on the wrong shelf with bottles of HYDROcodone-acetaminophen. Finally, the visual similarity between the two medications made it difficult to detect the error during counting and verification.
Due to the ongoing reports of RTS-related errors and the potential for patient harm, ISMP published its Best Practice 7, “Maximize the use of technology to prevent errors during the return-to-stock (RTS) process,” in the ISMP Targeted Medication Safety Best Practices for Community Pharmacy. It is important for both pharmacy dispensing system vendors as well as pharmacies to implement the different elements of this Best Practice.
For example, pharmacy dispensing systems should generate specific labels to apply to prescription bottles that require RTS. The RTS labels should include the drug name, dosage strength, expiration date, description (tablet shape, color, imprint code), and a barcode that can be used when filling a subsequent prescription. Utilize barcode verification throughout the RTS process to ensure the correct RTS label is placed on the correct RTS prescription, and during subsequent prescription fills. After affixing an RTS label to the prescription vial, place the RTS medications on pharmacy shelves and, as appropriate, use these to fill subsequent prescriptions. Develop functionality to automate and guide the use of available RTS medications to fill prescriptions before reverting to sending prescriptions to an automated dispensing system for filling.
The reporting pharmacy also identified opportunities to enhance their CS perpetual inventory process. At the time of the event, dispensed quantities were documented electronically only after dispensing. The pharmacy is now exploring ways to incorporate a pre-dispensing inventory check, especially for medications with RTS vials, to improve accuracy and accountability.