Practitioners' Reporting News

Similar Product Name Abbreviations

Issued November 25, 2003

The following error descriptions and recommendations are summarized from reports received through the USP Medication Errors Reporting (MER) Program. These cases were received between May–September 2003.

Error description: A pharmacist dispensed Ortho Tri-Cyclen® instead of Ortho Tri-Cyclen® Lo. The physician hand wrote the prescription as "orthotricyclen l0." The lower case letter "l"–rather than a capital letter "L"–was interpreted as ten (10) cycles. The patient had the prescription filled previously at another pharmacy and recognized the difference in packaging.
Reporting pharmacist's recommendation: Pharmaceutical representatives can emphasize to physician's to use the capital letter "L" when writing for the "Lo" product.


Photo of confusing order for Ortho Tri-Cyclen Lo

Error description: A patient's blood sugar was 202. According to the sliding scale order, the chart read for FS 201-250, give "2H + 8N," intended for 2 units Humalog and 8 units NPH insulin to be given. The nurse read the order to mean 24 units Humalog® and 8 units NPH and administered those doses. Compounding the problem was the physician's handwriting, which was very difficult to read. The patient complained of feeling clammy and was found to have a blood sugar of 37. When the pharmacy receives orders for sliding scale insulin, the pharmacist enters "Sliding Scale Insulin–see chart for specific orders" on the MAR. This is done because sliding scale orders can change constantly. The facility has a flow sheet for treating diabetic patients that lists the patient's finger stick history and how much insulin was given, but the nurse did not refer to this document.


Photo of confusing order for Humalog

Error description: A physician wrote a prescription for "PTU" (propylthiouracil–for hyperthyroidism) 50 mg three times a day. The patient was given Purinethol® (for leukemia and non-Hodgkin's lymphomas) 50 mg, 2 tablets three times a day. The patient developed pancytopenia, hepatotoxicity, and stomatitis.

Error description: A nurse called the pharmacy inquiring about "DHT 40 mg." The pharmacy does not stock DHT™ (dihydrotachysterol) and questioned the nurse about the strength, as DHT is not available in 40 mg. The nurse called the physician's office requesting clarification of the order. The order was actually written for "d4T" (abbreviation for Zerit® [stavudine]). DHT is used to treat hypocalcemia, while Zerit is for HIV infection.
Reporting pharmacist's recommendation: Physicians should spell out the complete name of the medication.

Error description: A physician ordered a "Pit drip mixed 100 units in 100 cc NS to run at 1-4 units/hr." The nurse verified with the physician that the order was for "Pitocin®, the drug used in OB patients" (for induction of labor). The physician confirmed the order. A call was placed to the pharmacy for a stat Pitocin drip mix, 100 units in 100 mL of normal saline. The nurse told the pharmacist that in her experience, she had never used Pitocin for blood pressure support. The pharmacist asked the nurse if the physician may have said Pitressin® instead. The nurse thought about it for a moment and told the pharmacist she would call back. Several minutes later, the nurse called the pharmacist back and explained that the physician insisted they were the same thing. Several hours later, the physician called the nurse to acknowledge the error and confirm that the order should be for Pitressin. The similarity of brand names was implicated as a cause of this error.

To prevent these and similar errors from occurring, encourage practitioners to avoid the use of abbreviations, including those for drug names. Practitioners may also wish to initiate support for the effort to include the brand and generic names, and to include a diagnosis with the order or on the prescription.

Practitioners are encouraged to report similar potential or actual medication errors to the USP MER Program at www.usp.org/patientSafety/mer/. Reporting forms can also be printed at that address or requested via Email at or by calling 1-800-23-ERROR (1-800-233-7767).


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.