Piscataway, NJ—More than a third of patients who were sent home from hospital emergency departments (EDs) had at least one potential drug interaction resulting from prescriptions provided at discharge.

That’s according to a study in the American Journal of Emergency Medicine. A retrospective chart review led by Rutgers University’s Ernest Mario School of Pharmacy found that prescriptions results in problematic drug combinations for 38% of those patients.

“If a new prescription given in an emergency department has a negative interaction with a medication that a patient is taking, the provider should consider an alternative,” explained colead author Patrick Bridgeman, PharmD, a clinical assistant professor of pharmacy practice and administration at Rutgers Ernest Mario School of Pharmacy. For example, if a patient is taking a lisinopril—a diuretic to treat high blood pressure—at home, the doctor would want to reconsider prescribing that patient ibuprofen because there could be an interaction that may be harmful to the patients’ health.”

The study, conducted from August 1, 2015 to August 31, 2015, reviewed 500 patient charts, finding 429 drug-drug interactions (DDIs) among 858 prescriptions written. While 15.6% of the DDIs were classified as B, which requires no modification of therapy, 60% were risk-rating category C, requiring monitoring of therapy, and another 22% were category D, which calls for considering therapy modification. Identified as category X DDI were 1.6% of prescriptions, with the recommendation to avoid the combination altogether.

The drugs most commonly associated with DDIs were oxycodone/acetaminophen, ibuprofen, and ciprofloxacin, researchers point out. Overall, pain medications were the likeliest to cause an interaction, followed by the other medications.

Study authors provided the following examples of interactions:
• Oxycodone/acetaminophen and fluoroquinolones has been associated with neurologic disorders such as seizures, delusions, and hallucinations.
• Oxycodone/acetaminophen and hydrochlorothiazide potentially could decrease the effectiveness of the diuretic and cause significant drops in blood pressure or sodium levels, which could lead to an increased risk of falls.
• Lisinopril and ibuprofen can cause increased rates of kidney damage.

“DDIs are occurring upon discharge from a large, urban, tertiary care, academic medical center. Many of the DDIs identified do not require any modification to therapy,” the researchers conclude. “However, 23.6% of identified DDIs required modification or were contraindicated. A majority of the category X drug interactions involved QT prolongation.”

“Most times, negative interactions can be avoided with thorough monitoring and a complete change in therapy is not needed. However, patients often may not know what medications they are taking at home, and emergency departments do not have standard procedures to identify medication interactions,” Bridgeman noted.

He recommended that physicians weight risks and benefits of adding a medication, and consult an ED pharmacist if patients have a complex medication list.

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