APRIL
2001
SAFETY CONCERNS SURROUNDING THE USE
OF LOW MOLECULAR WEIGHT HEPARINSLow molecular weight heparin products provide effective prophylaxis and treatment for deep vein thrombosis and are useful in preventing ischemic complications in unstable angina and non-Q wave myocardial infarction. Since these products have been on the market, there has been clear evidence that safeguards are not fully in place to prevent concomitant use of low molecular weight heparins and unfractionated heparin. According to a recent Institute for Safe Medication Practices report, concurrent use of these medications has resulted in three voluntarily reported deaths in the past year. The first case involved a 62-year-old patient with unstable angina who died after receiving an initial dose of FragminÒ (dalteparin) in the emergency department and then IV heparin along with a thrombolytic when he exhibited signs of a myocardial infarction. The second reported death occurred when a 42-year-old patient with an upper extremity thrombosis suffered an intracranial hemorrhage. The physician had accidentally prescribed LovenoxÒ (enoxaparin) and initiated a heparin protocol. The most recent case led to the death of a hospitalized 86-year-old woman with a history of atrial fibrillation, hypertension, lethargy, and constipation. A consulting cardiologist started the patient on enoxaparin and warfarin was added to the regimen the following day. Later in the week, a gastroenterologist recommended a colonoscopy; warfarin was discontinued and unfractionated heparin was started. However, enoxaparin administration continued every 12 hours. The patient eventually died from internal bleeding despite discontinuation of the enoxparin and unfractionated heparin and aggressive treatment.
Appropriate safety practices must be implemented in order to prevent these deadly events associated with low molecular weight heparins. Thorough review of the patient’s total drug regimen is key to safe use of all forms of heparin. It is imperative for prescribers, pharmacists, and nurses to consider current and recent drug therapy before ordering, dispensing, and administering any of these products. Special attention must be given when low molecular weight heparins are administered in the emergency department (ED). The ED is often considered an isolated practice area and orders for low molecular weight heparins and other heparin products may not be communicated to the pharmacy. Protocols, guidelines, and standard order forms prominently remind practitioners to assess all drug therapy (including in the ED) and avoid concomitant use when indicated (e.g. a heparin infusion should not be started if low molecular weigh heparin has just been administered, etc.). Current practices in place at KUMC to prevent medication errors with heparin products include computerized warnings for duplication of heparin therapies, pharmacist review of patient’s chart and MAR assessing the appropriateness of heparin therapy, and pharmacist review of patient’s laboratory values prior to dispensing heparin products.
