Attention should be paid to drug name suffixes to prevent mixups.
Dr. Gaunt is a medication safety analystand the editor of ISMP MedicationSafety Alert! Community/AmbulatoryCare Edition.
Drug name suffixes are confusingenough without coining our own. Opana(oxymorphone) 10 mg every 4 to 6hours for moderate-to-severe pain wasprescribed for a patient. On the prescription,the physician included the suffix"IR" (eg, "Opana 10 mg IR") to indicatethat the immediate-release productwas to be dispensed. Because no actualproduct is called "Opana IR," the pharmacyinterpreted the prescription as"Opana ER" (oxymorphone extendedrelease), which is intended to be administeredevery 12 hours.
It is unknown if the pharmacistreceived any computer alerts or drugutilization review warnings regardingthe high dose. It seems clear, however,that neither the pharmacy computersystem nor the patient's insurance planforced a hard stop on the filling of theprescription. The patient's insuranceapproved the prescription, and the pharmacydispensed 45 tablets of OpanaER labeled with instructions to take 1tablet every 4 to 6 hours. Once home,the patient looked at the prescriptionlabel and medication more closely andidentified the mistake; however, the prescriptioncould not be corrected untilthe next day.
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In another event, a physician assistantwrote a prescription for a patient, whichwas misread by a pharmacy technicianas "Vicodin ES" (hydrocodone 7.5 mg,acetaminophen 750 mg). Upon closerexamination, the pharmacist thoughtthat the suffix looked more like "RS."The pharmacist called the prescriber'soffice and learned that the physicianassistant had used "RS" to indicate "regularstrength." Vicodin (hydrocodone 5mg, acetaminophen 500 mg) was subsequentlydispensed. Because numerousbrand and generic combinations ofhydrocodone and acetaminophen productsare available, a large potential forconfusion exists.
Adding a suffix when a suffix is notpart of the name can lead to misinterpretation.To minimize the risk of confusion,avoid using nonexistent suffixes.If you do not recognize a suffix writtenon a prescription, verify the intendedmedication with the prescriber. Whengiving or repeating back verbal orders,practitioners always should use the fullwords "extended release" or "sustainedrelease," not abbreviations. Involvingpatients also may help; practitionersshould alert patients to possible confusionbetween the various formulationsand suffixes.
Byetta (exenatide) is the first in a classof new antidiabetic drugs called incretinmimetics. The medication is usedto improve glucose control in adultswith type 2 diabetes. Exenatide enhancesglucose-dependent insulin secretion,increases B-cell growth/replication,slows gastric emptying, and maydecrease food intake. Byetta is suppliedas a sterile solution for subcutaneousinjection containing 250 mcg/mL ofexenatide in a 5-mcg per dose, 60-dose,1.2-mL prefilled pen (NDC 66780-210-07), and in a 10-mcg per dose, 60-dose,2.4-mL prefilled pen (NDC 66780-210-08). The 5-mcg pen delivers 0.02 mL peractivation, and the 10-mcg pen deliverstwice that amount. One problemreported with this pen is related to theproducts' NDC numbers, which differonly by the last digit. The last 2 digitsmay not be read by some bar-code scannersused during the dispensing processin some facilities and community pharmacysettings.
Additionally, the manufacturer andproduct codes in the NDC numbers forboth pen injectors are the same. Thissimilarity in NDC numbers increasesthe risk that manual checks of the NDCnumber may not catch product mix-ups,as many pharmacists use only the middle4 digits of the NDC number to verify theproduct. As a result, the wrong size penhas been dispensed. We have notifiedthe manufacturer to request a distinctlydifferent NDC number for each size pen.When manually verifying these products(and others), ensure the complete NDCnumber is used.