From the May 2007 issue

In a hospital’s outpatient pharmacy, a prescription for SINEQUAN (doxepin) 10 mg, with the directions to take 5 capsules daily, was mistakenly entered into the computer and dispensed as Sinequan 100 mg. Neither the technician who pulled the 100 mg strength from the shelf nor the verifying pharmacist caught the error. The patient took 500 mg of doxepin daily for one month before the error was corrected. The error was discovered when the prescription was transferred to another pharmacy and the receiving pharmacist expressed concern about the high dosage. Since the error, the patient had been experiencing residual drowsiness and fatigue. The physician slowly decreased the dosage. The pharmacy software system may have played a role in the error. Upon entering “Sinequan” on the product line, the list of matching results placed Sinequan 100 mg on the first line followed by Sinequan 10 mg. It’s believed that the sequential listing of both strengths, with a tenfold difference, contributed to the selection of the wrong strength, as did the listing of the higher strength first.

The pharmacy has contacted the software vendor to ask about the logic used by its system when alphabetically sorting drug information, as some products (e.g., amiodarone) appeared on alphabetical listings with the lower strength first. This inconsistent presentation of product listings contributes to the risk of errors. The pharmacy has now added an asterisk to the doxepin 100 mg strength name (doxepin *100 mg) to cause it to fall to the bottom of the alphabetical sort until a better sort logic and a permanent solution can be programmed. However, this may not be a safe option if electronic calculations of doses and dose limits originate with information in the field that contains the asterisk. In these cases, the asterisk may interrupt or alter the calculation process. ISMP will also follow up with software and drug information vendors to help develop consistent ways to sort from lowest to highest strengths. The temporary measure (asterisks) taken by this pharmacy might be considered for other drugs with 10-fold strength differences, such as KADIAN (morphine sulfate extended release), which has a new 200 mg strength and an existing 20 mg strength, and a new 10 mg strength with an existing 100 mg strength.