From the April 2009 issue

A patient received the incorrect dose of digoxin for six months from an ambulatory care pharmacy in a community health clinic. Instead of 250 mcg daily, the patient received digoxin 125 mcg daily. The error was discovered when the prescriber sent a new prescription to the pharmacy and the medication was filled incorrectly by a technician. When the verifying pharmacist returned the prescription to be corrected, the technician reported that the dose was the same as what the patient had taken before. It was discovered that the previous prescription had been entered and dispensed incorrectly. Both the patient and prescriber were notified. Thankfully, no adverse event was noted. The pharmacy’s investigation of the event revealed that one cause may have been the lack of verification when the first prescription was placed “on hold” in the pharmacy computer system. When a patient presents a prescription to the pharmacy that does not need to be filled immediately (e.g., a patient is already taking the medication and has refills left or may be too early to fill), it can be entered into the pharmacy computer system and placed “on hold.” This way, the patient does not need to keep track of the paper copy and the dispensing process takes less time when the patient needs to fill that prescription. As order entry is occurring when the prescription is placed on hold, it is critical that the prescription undergoes the same verification process used when a prescription is actually dispensed. This includes conducting a double check of the order entry by comparing the information in the computer system to that contained on the original prescription. When the prescription is eventually dispensed, verification against the original prescription or its scanned image should be done again. Of course, final verification should include a review of the patient’s profile and a prospective drug utilization review. Engaging the patient as a final check during patient education may also have helped catch the error.