United States of America. The ISMP has received another report of name confusion, in this case concerning Neumega (oprelvekin) and Neupogen (filgrastim).

Neumega is indicated for the prevention of severe thrombocytopenia and to reduce the need for platelet transfusions following myelosuppressive chemotherapy in patients with non-myeloid malignancies who are at high risk of severe thrombocytopenia. Neupogen is indicated for reduction in duration of neutropenia and in the incidence of febrile neutropenia in patients treated with established cytotoxic chemotherapy for non-myeloid malignancy.

An oncology patient (being treated as an outpatient) had a prescription for Neumega 3,500 micrograms via subcutaneous injection to treat chemotherapy-induced thrombocytopenia. The patient was also receiving Leukine (sargramostim) for a low white blood cell count.

A pharmacist misread the order for Neumega as Neupogen and the dose was also misread. The patient received Neupogen 350 micrograms via subcutaneous injection. The mistake was discovered after the second dose. The patient was monitored for adverse effects or lasting sequelae from the Leukine-Neupogen combination, but none were identified. The patient’s platelet count was not affected and his WBC count returned to normal limits within the next two days. However, such an error could be serious if the patient was severely thrombocytopenic and needed the platelet “boost” by Neumega to prevent bleeding. Similarly, a leukopenic patient would receive no benefit from administration of Neumega.

The ISMP points out that the dose of Neumega is 50 micrograms/kg/day and that of Neupogen is 5 micrograms/kg/day; however, despite the 10-fold difference in the doses, the numbers are similar enough to cause confusion, added to the fact that the names have identical first syllables and both drugs stimulate the haematopoietic system to increase production of components lost during cancer treatment. In this case, the dose of 3,500 micrograms (versus 350 micrograms) went unnoticed, possibly because both drugs were to be given subcutaneously in a small volume.

Physicians are advised to include in their orders “for platelets” or “for white cells” to reduce the likelihood of a mix-up between these two products.

Reference: ISMP Medication Safety Alert! Vol. 3, Issue 15, 29 July 1998.