Beta Block this order

From the Nov. 5,1997 Issue

PROBLEM: An admission order to the intensive care unit stated: "Inderal 20 mg orally q 6 hours. If patient cannot take PO medications give 1 mg Inderal IV q 6 hours."

Later that day, the patient transferred to a stepdown unit. The stepdown unit clerk called the pharmacy clinical coordinator before the patient arrived to ask for information about IV propranolol because staff was unfamiliar with that use. No information about the patient or the specific order was given.

The clinical pharmacist printed information from MICROMEDEX ^® that stated the IV form could be infused at a maximum rate of 2-3 mg per hour. In clinical practice, the amount of IV Inderal^® (propranolol) required to replace PO propranolol varies depending on individual pharmacokinetics and other clinical circumstances. USP DI 1997 states that an IV dose of 10% of the oral dose may be used temporarily to replace the oral dose in patients undergoing surgery. He took the information from MICROMEDEX on the IV infusion to the stepdown unit at 5 pm, but because nurses were in the middle of report, he gave the information to the unit clerk. The pharmacist left his pager number with the instruction that, if there were any questions, he could be paged. He also left the same information in the pharmacy.

he next day, the clinical coordinator was told that there was a medication error the previous evening on the stepdown unit with IV propranolol. When the patient had transferred to the stepdown unit, as was the practice, the intensive care unit had rewritten the transfer orders. The rewritten orders read "Inderal 20 mg orally q 6 hours, if patient cannot take PO give Inderal IV."

Unfortunately, the "1 mg" was omitted. The nurse called the pharmacy for additional ampuls because she did not have enough IV propranolol in floor stock to prepare a 20 mg infusion. The pharmacists, who were following the information left by the clinical coordinator, refused to send the propranolol to make 20 mg infusions every six hours. Using the MICROMEDEX information as a guideline, the pharmacists and nurse agreed to an infusion of 3 mg/hr. The pharmacy sent 30 one mg propranolol ampuls to the unit, and the nurse prepared an 18 mg (18 ampuls) infusion to run in over six hours.

After receiving approximately 8 hours (24 mg) of propranolol, the patient's blood pressure dropped to 70/50 with consequent feelings of dizziness. The infusion was stopped, and the patient, who was already on a cardiac monitor, was watched through the rest of the evening. Her symptoms subsided later. There were no apparent lasting effects of the propranolol infusion.

SAFE PRACTICE RECOMMENDATION:The primary problem in this situation was lack of knowledge about the conversion from PO to IV propranolol. The clinical coordinator did not know and did not ask the PO dose the patient was to receive, which would have tipped him off to an appropriate IV dose. For a patient receiving a total daily oral dose of 80 mg, a more appropriate temporary daily IV dose would be approximately 8 mg (10% of the oral dose). Miscopied orders were not double-checked, and the drug information was left with the unit clerk instead of the nurse, which resulted in a missed opportunity to find out more patient information.

No one can be expected to know everything about every drug. However, any time more than 3 or 4 dose units have to be used to make a single dose, there may be an underlying error. Practitioners should also investigate doses when routes are changed. And, hopefully, by sharing information with each other in forums, such as the USP-ISMP Medication Errors Reporting Program, we will be able to learn from each other's mistakes.