What is Noxafil?
Noxafil (posaconazole) is used to help prevent people with weakened immune systems from contracting certain invasive fungal infections caused by Aspergillus and Candida. It is an antifungal medication available in two oral formulations: delayed-release tablets and an oral suspension. The oral formulations are dosed differently, due to differences in how the medicine is absorbed and handled by the body. This means they can not be interchanged without adjusting the dosage.
The FDA approved the delayed-release tablet formulation of Noxafil in November 2013. Since that time, the FDA has received eleven (11) reports of the wrong oral formulation being prescribed and/or dispensed to patients.
In one of the 11 cases, a patient was taking Noxafil delayed-release tablets for prophylaxis of invasive Aspergillus and Candida infections, but the pharmacy replaced the tablets with the oral suspension directly without consideration of the different dose and frequency of administration of the oral suspension and resulted in an underdose. The patient was reported to have later died from a stroke related to an invasive Aspergillus infection, according to the FDA.
In cases like these, it may be possible to sue the prescribing doctor, pharmacist and the manufacturer. Arguably, the manufacturer should have had something on the labels making it clear that the two formulations are not interchangeable. New labeling, discussed below, does provide a warning.
10 Cases Where Patients were Sickened by a Noxafil Overdose
The other ten case reports described patients switching from Noxafil oral suspension to the delayed-release tablets, but were prescribed or dispensed the same dose and frequency of administration as the oral suspension. For example, one patient received two 100 mg delayed-released tablets taken three times per day, which is twice the recommended Noxafil dose of three 100 mg delayed-release tablets taken once per day for prophylaxis of invasive Aspergillus and Candida infections. Some of the patients reported adverse reactions such as nausea and vomiting, and one patient presented to the hospital with these adverse reactions and was found to have a low serum potassium level.
FDA Approves Label Changes
According to reports received by the FDA, the cases of death and overdose above were a result of health care professionals (doctors and pharmacists) not knowing that the two oral formulations cannot be substituted for each other without adjusting the dose due to differences in how the medicine is absorbed and handled by the body.
Because of this confusion, FDA approved changes to the outer carton of Noxafil and Merck, the manufacturer, revised the prescribing information and the patient information in the drug label to alert patients and their health care professionals that the two oral formulations of Noxafil cannot be substituted for each other. The following appears on the product label:
Attention: Noxafil Oral Suspension and Delayed-Release Tablets are NOT interchangeable due to differences in the dosing of each formulation.