Practitioners' Reporting News

Medication Error Involving Insulin Attributed to Poor Handwriting

Issued August 2, 2002

Medication errors occur for a wide variety of reasons. One common cause, as seen through the USP Medication Errors Reporting Program (MER), is illegible handwriting. In a report received through the MER Program, poor handwriting was identified as the cause of a medication error that resulted in a diabetic patient receiving the wrong type of insulin.

A consulting physician wrote the following order for a patient:

The order includes several components of a properly written medication order including the name of the drug, the dosage form with "units" written out instead of abbreviated, and a time schedule instead of instructions to "Take as directed" (USP Quality Review #57). However, the pharmacist interpreted the word "Lantus" as "Lente". As a result, Lente® Iletin® II insulin was dispensed from the pharmacy. The patient received one dose of the Lente insulin before the error was discovered. The reporter noted that there was no adverse outcome to the patient.

Both drug products are used in the treatment of Diabetes Mellitus. Lantus®, manufactured by Adventis Pharmaceuticals, is the brand name for insulin glargine, a long-acting antidiabetic agent. Lente Iletin II, manufactured by Eli Lilly and Company, is the brand name for insulin zinc (Lente), an intermediate acting antidiabetic agent.

Reports of confusion between the Lantus and Lente proprietary names have been previously reported to the USP MER Program (USP Quality Review #76) Caution should be used when writing prescriptions or orders for drug products with brand names similar to other brand named drug products, generic names similar to other generic named products, or brand names similar to other generic named products. Illegible handwriting only adds to the potential for confusion.


Readers are advised that official USP cautions and warnings for drugs appear in the USP–NF or USP DI. Unless otherwise indicated, any advice or opinions expressed herein reflect solely the judgment of USP staff. Such statements are intended for further consideration and evaluation and may or may not be applicable to a particular practice. The USP Medication Errors Reporting Program is presented in cooperation with the Institute for Safe Medication Practices.