From the August 2007 issue

ISMP is receiving an increased number of reports of medication mix-ups involving prescriptions for regular insulin U-500 and insulin U-100. Prescribers have sometimes selected U-500 regular insulin in error from selection screens of electronic prescribing systems instead of U-100 insulin. The errors seem to be related to the position of insulin product listings on computer screens. For example, “Humulin R Injection Solution 100 UNITS/ML” might be one line apart from “Humulin R Injection Solution 500 UNITS/ML.” Also, depending on the screen size, the entire line, particularly the drug concentration, may not be visible. These factors make it easy for the prescriber to see only the first few words of the product listing. Also, since U-500 use is not common, prescribers may not look for information about concentration if they believe insulin is available only in a U-100 concentration. However, the use of U-500 insulin may be increasing due to the obesity epidemic, increased insulin resistance, use in insulin pumps, and prescriber's use of tight glucose control protocols. ISMP has contacted the major drug information system providers, Multum, First DataBank and Medi-Span, and each agreed to add the word “concentrated” immediately following the drug name and preceding U-500.

Depending on which system your computer uses, you should begin seeing the new listings in vendor updates now. If you control how drugs are listed in inventory screens in your setting, consider this change for your system. If U-500 insulin is not commonly used, consider listing it differently than other insulins so that it doesn’t appear on the screen with other insulin products. Adding a hard stop to all U-500 insulin orders–which requires prescribers and pharmacists to verify that the concentrated strength is intended for the patient–can also help prevent errors. Finally, if you do not have any patients who need U-500, don't stock it. That alone can decrease the potential for dispensing errors.