The soaring numbers of commonly used drugs with soundalike and look-alike names have prompted the U.S. Pharmacopeia to ask physicians and pharmacists to include an "indication for use" on prescriptions.
This and other recommendations are contained in U.S. Pharmacopeia's 8th annual MEDMARX report, which is based on a review of more than 26,000 records submitted to the MEDMARX database from 2003 to 2006.
The records implicate nearly 1,500 drugs in medication errors due to brand or generic names that could be confused. From these data, U.S. Pharmacopeia (USP) compiled a list of more than 3,000 drug pairs that look or sound alike, a figure that is nearly double the number of pairs identified in USP's 2004 report, said Diane Cousins, R.Ph.
"We were surprised to see that much of an increase in such a short time, and the concern is that this increase in products in the marketplace further raises the opportunity for error," said Ms. Cousins, USP's vice president of health care quality and information.
USP also operates, in conjunction with the Institute for Safe Medication Practices, the Medication Errors Reporting Program (MER), which allows health care professionals to confidentially report potential and actual medication errors directly to USP.
USP reviewed both MEDMARX and MER to summarize the variables associated with more than 26,000 look-alike and/or soundalike (LASA) errors, of which 1.4% (384) resulted in harm or death. More than 670 health care facilities contributed 26,000 records, according to the 400-page report.
"We looked at lists of the top 200 drugs prescribed and used in hospitals, and virtually every time, all of the top 10 appeared within the USP similar names list," Ms. Cousins said in an interview.
An important finding of this year's report is the role of pharmacy staff in LASA-related errors, she said. "Although pharmacy personnel, who are generally technicians, made the majority of errors, pharmacists as a group identified, prevented, and reported more than any other staff."
The report also identifies an emerging trend of look-alike drug names in computerized direct order entry systems as a source of confusion. "This trend will likely continue as these systems become a standard of practice," she said, adding that the LASA-related error problem is further compounded by the indiscriminate use of suffixes, as well as look-alike packaging and labeling.
Over the 3-year period, the drug most commonly confused with others was cefazolin, a first-generation cephalosporin antibiotic. "We found it to be confused with 15 other drugs, primarily antimicrobials, which might be explained by the fact that this is the most frequently used class of medications," said Ms. Cousins.
Among other major paired LASAs were cardiovascular medications, such as lisinopril and enalapril, and central nervous system agents, such as trazodone and chlorpromazine.
Drug mix-ups led to seven reported fatalities, including two deaths attributed to confusion over the Alzheimer's drug Reminyl (galantamine) and the antidiabetes drug Amaryl (glimepiride).
In 2005, recognizing the high risk of confusion and subsequent fatal hypoglycemia, Ortho-McNeil Neurologics Inc. announced that the name Reminyl had been changed to Razadyne to avoid confusion with Amaryl.
In another case, an autistic pediatric patient was given the wrong product when disodium EDTA (a hypercalcemia treatment) was administered instead of the chelation therapy calcium disodium EDTA, which is approved by the Food and Drug Administration for the treatment of lead poisoning and was prescribed in an attempt to help treat the patient's autism.
In another case, an emergency department physician was preparing to intubate a patient and calculated the dose for rocuronium (Zemuron), a preintubation agent used to assist with the procedure. The physician gave orders for the nurse to obtain the medication and indicated the volume to administer to the patient. The nurse obtained and administered the neuromuscular blocking agent vecuronium (Norcuron) instead. The patient received a large amount of the wrong agent, which led to a fatal heart arrhythmia.
The remaining three reported deaths involved mix-ups between the anticonvulsant primidone and prednisone; the antiepileptic drug phenytoin sodium and the barbiturate phenobarbital; and Norcuron and the heart failure treatment Natrecor (nesiritide recombinant).
Errors occur with over-the-counter medications, too. Ms. Cousins described the aural confusion when an order for Ferro-Sequel 500 mgan iron replacementwas transcribed as Serrosequel 500 mg and the order was misread as Seroquel 500 mgan antipsychotic.
The rate of mix-ups involving brand name versus generic drugs was about evenly split, 57% and 43%, respectively, Ms. Cousins said, adding that while most errors were made in pharmacies, many, such as the primidone-prednisone incident, are due to confusion over the prescribing physician's handwriting, which lead the pharmacist to issue the wrong drug.