Practitioners' Reporting News

Cases Submitted to MER—Trailing Zeros; Misunderstood Abbreviations; Calculation Concerns

Issued March 31, 2004

The following are various cases of medication error reports submitted through the USP Medication Errors Reporting (MER) Program in January 2004.

Case 1

Potential error: When the pharmacist was dispensing an injection of Hectorol®, it was noted that on the label the abbreviation of "µg" was used instead of "mcg." The dosing was also expressed with a trailing zero ("2.0" and "4.0").


Photo of Hectorol labeling*

Reporting pharmacist's recommendation: Due to the potential for error when using the abbreviation "μg" and trailing zeros, this type of labeling should be changed for patient safety reasons.

Case 2

Potential error: USP received two separate reports concerning Integrilin®. In the first report, a pharmacist noted that the new package insert for Integrilin has numerous references to the dosing of the drug using a trailing zero ("2.0" and "1.0," etc.). Practitioners may make an error when dosing patients due to this type of dosage expression. In the second report, the pharmacist was concerned about the new dosing guidelines for Integrilin. The manufacturer has converted from a serum creatinine dosing to a creatinine clearance calculation and recommends using the Cockroft-Gault formula. In the manufacturer's example, it states to use the weight in kilograms, but does not specify ideal, actual, or adjusted body weight (ABW). To compound the issue, personal digital assistant's (PDA's), pharmacy computer systems, and calculation systems present the creatinine clearance results without specifying which formula was used. For example, the facility had a patient whose creatinine clearance was based upon the patient's serum creatinine. The pharmacy calculated an infusion rate that differed from the physician's calculation. It was discovered that the pharmacy's computer utilizes ideal body weight and the physician's PDA uses ABW to calculate the creatinine clearance.

Case 3

Error description: A patient was found to be taking a 5-fold overdose of high potency morphine sulfate (100 mg/5 mL). The order was written for 1 & ½ "cc" every 4 hours as needed. The dispensing spoon packaged with the product was labeled as "tsp" and "mL". The patient misunderstood the abbreviation "cc" and took 1 & ½ teaspoonfuls of morphine sulfate. The meaning of the abbreviations "tsp," "mL," and "cc" were not clear to the patient and it is unlikely that the patient was counseled. The patient experienced short-term confusion and excessive drowsiness.


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Photo of morphine sulfate packaging/labeling*

Reporting pharmacist's action/recommendation: Concentrated forms of medication should never be dispensed with large volume measuring devices such as the dispensing spoon packaged with this product, which is labeled in teaspoonfuls.

Practitioners are encouraged to submit similar errors to the MER Program. MER is a nationwide program that makes it possible for health professionals who encounter actual or potential medication errors to report to USP confidentially and anonymously, if preferred. By sharing these experiences, pharmacists, nurses, physicians, and other healthcare practitioners contribute to improved patient safety and to the development of valuable educational services for the prevention of future errors. USP reviews each report for health hazards and forwards all information to the U.S. Food and Drug Administration (FDA) and the product manufacturer/labeler. USP will act as your liaison with the FDA and the manufacturer/labeler should you wish to submit a report confidentially.

Reports can be submitted online at www.usp.org/patientSafety/mer/ or by requesting a form at 1-800-23-ERROR (1-800-233-7767).

*All photos provided courtesy of the reporter or the Institute for Safe Medication Practices.


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.