Welcome to FDA Drug Safety Podcasts for health care professionals. This is Heena Patel, pharmacist from the Division of Drug Information.
On January 4, 2016 FDA cautioned that differences in dosing regimens between the two oral formulations of the antifungal Noxafil (active ingredient posaconazole) have resulted in dosing errors. 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 milligram for milligram substitution of the two formulations can result in drug levels that are lower or higher than needed to effectively treat certain fungal infections.
Prescribers should specify the dosage form, strength, and frequency on all prescriptions they write for Noxafil and pharmacists should request clarification from prescribers when the dosage form, strength, or frequency is not specified.
Noxafil is approved in two oral formulations: an oral suspension and a delayed-release tablet. It is also approved as an intravenous solution for injection. Noxafil is used to help prevent invasive fungal infections caused by Aspergillus and Candida. Noxafil is used in patients who have an increased chance of infection due to weakened immune systems. Noxafil oral suspension is also used to treat Candida in the mouth or throat area.
Our review of the FDA Adverse Event Reporting System (FAERS) database identified cases of dosing errors with Noxafil. Noxafil was approved in 2006 as an oral suspension formulation. Since the approval of Noxafil delayed-release tablets in November 2013, FDA received eleven reports of the wrong oral formulations being prescribed and/or dispensed to patients. One case resulted in death, and another in hospitalization. The reports indicated these outcomes were a result of health care professionals not knowing that the two oral formulations cannot be substituted for each other without adjusting the dose.
The outer carton of Noxafil was changed and the manufacturer Merck revised the prescribing information and the patient information in the drug label to alert patients and health care professionals that the two oral formulations of Noxafil cannot be substituted for each other.
Side effects involving Noxafil should be reported to FDA’s MedWatch program at www.fda.gov/medwatch.
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- FDA Drug Safety Communication: FDA cautions about dosing errors when switching between different oral formulations of antifungal Noxafil (posaconazole); label changes approved
- FDA Drug Safety Podcast: FDA cautions about dosing errors when switching between different oral formulations of antifungal Noxafil (posaconazole); label changes approved