Study objectives: More than 7,000 deaths annually have been attributed to medication errors, and emergency departments (EDs) have one of the highest medication error rates. Although completed errors have been described, so-called “near misses” are less well understood. We describe the errors that emergency physicians make in prescription writing that result in a pharmacy's inability to fill the prescription.

Methods: At our tertiary care, university ED (64,000 patients per year), prescriptions for patients discharged from the ED are handwritten and contain a telephone number for any pharmacy to call if the pharmacy cannot fill the prescription as written. For 12 hours a day, the pharmacist can reach a dedicated nurse administrator who records the reason for the prescription “callback” and attempts to solve the difficulty. We reviewed and described all ED prescriptions resulting in a pharmacy callback between 8 am and 8 pm for 21 consecutive months.

Results: One thousand five hundred eleven ED prescriptions could not be filled as written and resulted in a pharmacy callback. Reasons included illegible text (37%), medication not covered by patient insurance (22%), incorrect dosing (14%), missing number to dispense (9%), missing Drug Enforcement Administration or license number (5%), missing signature (2%), wrong patient name (1.4%), no patient name (1.3%), medication not available at pharmacy (0.8%), called to verify (0.8%), patient allergic to medication (0.4%), medication interaction with patient's other medication (0.2%), patient already on similar medicine (0.1%), miscellaneous (6%). The most common classes of medication resulting in a callback included antibiotics (75), nonsteroidal anti-inflammatory drugs (12), antihistamines (12), antacids (9), opiates (8), antiemetics (7), and asthma medications (6).

Conclusion: Most errors in ED prescription writing that result in pharmacy callbacks involve illegible text, incorrect doses, missing information, or off-formulary items. Computerized prescription writing, which corrects dosing errors and prompts for all necessary elements of a prescription, could reduce pharmacy callbacks by at least 62%, resulting in an estimated 535 fewer pharmacy callbacks per year.