Medication Formulation Error Leads to Overdose

pillsWe need systems that support our clinicians in delivering the safest, high-quality care. When our systems do not do this, we are at risk for errors. In this issue of Safety Matters, we reflect on a case where our electronic ordering system did not give our care providers specific information about a certain medication. The result? A patient received an overdose that required an immediate response from Poison Control and an extended stay at BWH. Fortunately, he recovered, and we put in place some changes that better support our clinicians in differentiating between specific formulations of medications.

Thanks for reading,





What Happened

A patient visited our Emergency Department (ED) for shortness of breath.

During the admission process, a resident placed orders for the patient’s home medications, including diltiazem, which treats high blood pressure. The resident compared the list of medications in the electronic health record (EHR) to the patient’s list of home medications and noticed conflicting information about diltiazem. The EHR listed a version of the medication that was immediate release, while the home list had a different, higher dosage that was extended release (meaning the drug is slowly released into the bloodstream over a certain number of hours).

The resident meant to order the extended release for the patient but accidentally ordered immediate release at much too high a dosage.

The EHR alerted the resident of the high dosage, but did not specify that it was for immediate release. The resident believed she had ordered extended release and overrode the alert.

The pharmacist reviewed and approved the order, also overriding a high-dose alert. The nurse confirmed the drug name and dose with the patient, but did not ask if he was taking immediate or extended release before administering the medication.

Five minutes later, the error was realized when the physician assistant was reviewing the patient’s home medication list. The care team disclosed the error to the patient, who recovered after an extended stay at BWH.

What Went Wrong 

In the EHR, diltiazem immediate release is listed as “diltiazem.” Slower release formulations are listed with letters after the drug name, such as “XR” for extended release. The physician and nurse both believed the medication selected was extended release. The pharmacist was aware that the order was for immediate release, but thought that the high dosage might have been warranted depending on the patient’s medical condition.

What We Are Doing 

We have updated the medication display in the EHR. Now, when a provider searches for diltiazem, the EHR indicates immediate release “IR” in addition to extended release “XR” so there is no longer any ambiguity.

The alert display of diltiazem has also been updated in the EHR. Diltiazem immediate release alert language now includes the “IR” designation. We have also added these letters to other appropriate immediate release medications in the EHR to prevent a similar error happening with other medications.

There is also ongoing work to refine alerting, with considerable attention toward preventing alert fatigue for clinicians.

Just Culture Corner: Preventing system error

One of the first steps in assessing an event from a Just Culture perspective is to analyze the systems in place at the time of the error. In this case, the user interface on the electronic medication ordering system lacked a clear designation for different formulations of diltiazem. This system vulnerability increased the likelihood that the ordering provider would inadvertently order the wrong formulation (in the Just Culture framework, we call this a human error: an inadvertent slip, lapse or mistake).

The response to the employee is to provide support. We are all human and prone to error, and we can help the employee understand that another smart careful person could have made the same error. We then want to engage the employee in helping to identify the system solution that will mitigate future risk of the same error.

Learn more about Just Culture.