ISMP warns of potential errors when emergency compounding Tamiflu

Because Tamiflu has been in short supply recently, pharmacists and other healthcare providers are being warned about confusion over emergency compounding of the drug.

Tamiflu’s manufacturer, Genentech, has Tamiflu 6 mg/mL oral suspension in 60 mL bottles on intermittent back order. The company is releasing product as it becomes available, but also provides instructions for compounding an extemporaneous 6 mg/mL oral suspension from 75-mg capsules, if required, according to The Institute for Safe Medication Practices (ISMP).

“A detailed recipe is available in the product prescribing information or online. However, unless prescribers specify the patient’s dose in milligrams, a dosing error is possible,” according to a statement from ISMP.

Last year, Genentech decreased the commercial strength of Tamiflu oral suspension from 12 mg/mL to 6 mg/mL.  Prescribers expecting the 12 mg/mL product may be unaware of the new concentration, according to ISMP. “To complicate matters, the manufacturer previously recommended preparing the compounding suspension in a 15 mg/mL strength, which means that some pharmacists may refer to this old recipe when compounding. It is also possible that all three concentrations might still be listed in some systems,” ISMP stated.

While no errors with Tamiflu dosing have been reported to ISMP this year, the organization wants pharmacists and other healthcare providers to be cautious. “We are concerned that their recipe cards and computer systems will still reflect the old concentration,” said Michael Cohen, executive director of ISMP.

All physicians should be instructed to express Tamiflu dose in milligrams and not volume, according to ISMP. “In hospitals with computerized prescribing, check and update computer databases and pharmacy compounding recipes where necessary to reflect the 6 mg/mL concentration. Otherwise, direct communication is necessary between the prescriber and pharmacist to ensure the intended dose reaches the patient,” ISMP stated.