Practitioners' Reporting News

Medication Error Deaths Reported: Combinations of Unfractionated and Low Molecular Weight Heparin

Issued July 25, 2001

In the past year, the USP Medication Errors Reporting (MER) Program has received four reports of deaths that may have resulted from the administration of unfractionated Heparin, following or concurrently with, doses of low molecular weight Heparin. Low molecular weight Heparins are accepted treatments for unstable angina, non-Q-wave myocardial infarction, pulmonary thromboembolism, and deep vein thrombosis. These errors occurred in both emergent and non-emergent care units and involved multiple levels of hospital staff, including prescribing physicians, nurses, and pharmacists.

In the most recent report, a patient on a medical unit was started on Warfarin and Enoxaparin following a cardiology consult. After a subsequent GI consult, the Warfarin treatment was discontinued to prepare the patient for a procedure, and the patient was started on Heparin. The nurse taking the orders discontinued the Warfarin and wrote the Heparin order on the MAR. The order, however, was not faxed to the pharmacy, and therefore was not checked by pharmacy for drug interactions and duplications. Because the Heparin dose was not provided by pharmacy, it was unavailable for the patient and was "borrowed" from another patient. The Enoxaparin order remained active, so the patient continued to receive low molecular weight Heparin along with unfractionated Heparin. That evening, the patient's post-infusion partial thromboplastin time (PTT) was reported at greater than 90 seconds, and contrary to hospital protocol, the value was not promptly reported to the health care team. Despite discontinuation of Enoxaparin and Heparin the following morning, and subsequent aggressive treatment, the patient died several days after the initial error.

In two other reports citing patient death, initial emergency room staff administration of Dalteparin or Enoxaparin was overlooked, and Heparin was started too soon afterwards. And, in a final report involving a fatality, a physician ordered both Enoxaparin and Heparin for a patient simultaneously, by telephone, and no one on the health care team picked up on the duplication of therapy.

In addition, the MER program recently received a report from a hospital pharmacist citing incidents where both a low molecular weight Heparin and unfractionated Heparin were entered into patients' computerized pharmacy profiles utilizing the MS

MEDS
system. Fortunately, in those cases the error was caught prior to reaching the patient. The concern, however, is that the computer system safeguards and drug interaction warnings are not sufficient to eliminate this potentially life-threatening error from occurring. Warning messages for such combinations can be overridden just by pressing the computer's enter key. In response to this report, the Cerner Corporation reports that it is planning to include a number of changes in the upcoming release of its inpatient pharmacy system, MS
MEDS
version 7.0. The new software will include duplicate therapy error messages for combinations of unfractionated and low molecular weight Heparin that come up in separate screens and require a particular user input, other than the enter key, to cancel the warning. Pharmacists are cautioned to examine their own software's warnings for multiple anticoagulant and antithrombolytic medications to reduce the likelihood that they could miss such a warning.

These reported errors indicate a need for protocols to prevent the administration of Heparin soon after or during low molecular weight Heparin therapy. Physicians, pharmacists, and nurses must also be made aware of the dangers of such combinations, and system safeguards should be enacted at multiple levels to prevent these tragic errors.

An Institute for Safe Medication Practices (ISMP) report of this problem suggests a number of relevant precautions, including the placement of warnings on the charts of patients receiving low molecular weight Heparin, processing and control of Heparin orders by hospital pharmacies, and review of patients' entire drug regimens before the administration of Heparin products. For the entire ISMP report, visit www.ISMP.org/MSAArticles/HeparinAlert.html.


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.