Antifungal dosing errors prompt FDA warning

April 10, 2016

Prescribing protocols for Noxafil delayed-release tablets and oral suspension are NOT interchangeable. Errors have resulted in hospitalization and death.

Since the approval of Noxafil delayed-release tablets in November 2013, FDA has received 11 reports of the wrong oral formulations being prescribed and/or dispensed to patients. One case resulted in death and another in hospitalization.

The agency has now issued a caution about differences in dosing regimens between the two oral formulations - the delayed-release tablet and an oral suspension -  ­of Merck’s antifungal drug Noxafil (posaconazole) that have resulted in dosing errors.

Noxafil helps prevent certain invasive fungal infections caused by Aspergillus and Candida. The oral suspension is also used to treat thrush, a fungal infection in the mouth or throat area caused by Candida.

No direct substitutions

“To help prevent additional medication errors, the drug labels were revised to indicate that the two oral formulations cannot be directly substituted for each other, but require a change in dose. Direct mg-for-mg substitution of the two formulations can result in drug levels that are lower or higher than needed to effectively treat certain fungal infections,” FDA said in a statement.

FDA advises prescribers to specify the dosage form, strength, and frequency on all prescriptions they write for Noxafil.  Pharmacists, meanwhile, should request clarification from prescribers when the dosage form, strength, or frequency is not specified.