The Medical Letter on Drugs and Therapeutics
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1461
In Brief: A New Formulation of Posaconazole (Noxafil)
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The FDA has approved an IV formulation of the antifungal drug posaconazole (Noxafil - Merck) for prophylaxis of Aspergillus and Candida infections in adults at high risk for these infections, such as those with prolonged neutropenia. Posaconazole is also available as delayed-release tablets and an oral suspension.

With activity against Aspergillus and Candida, posaconazole has an antifungal spectrum similar to that of voriconazole (Vfend, and generics), but unlike voriconazole it is also active against many species of Mucorales (formerly called Zygomycetes), such as Mucor and Rhizopus. Posaconazole has variable activity against Fusarium spp. and Scedosporium spp.1

Fever, diarrhea, nausea, vomiting, rash, headache, fatigue, hypokalemia, QT interval prolongation, and abnormal liver function have been reported with posaconazole. Arrhythmias, toxic epidermal necrolysis, angioedema, and anaphylaxis have occurred rarely.

Posaconazole is primarily metabolized via UDP glucuronidation; it is also a substrate of P-glycoprotein (P-gp). Drugs that inhibit or induce these clearance pathways may alter serum concentrations of posaconazole. Posaconazole is a strong inhibitor of CYP3A4 and may increase serum concentrations of drugs that are primarily metabolized by this pathway.2 Taking posaconazole with other drugs that prolong the QT interval (www.crediblemeds.org), especially those metabolized by CYP3A4, may increase the risk of QT interval prolongation.

The new formulation of posaconazole is available in 300 mg/16.7 mL vials. The recommended dosage is 300 mg administered intravenously over 90 minutes twice on day 1 and once daily thereafter. To avoid accumulation of the vehicle, patients with moderate or severe renal impairment should not receive IV posaconazole. One vial of Noxafil costs $530.50.3

  1. Antifungal drugs. Treat Guidel Med Lett 2012; 10:61.
  2. Inhibitors and inducers of CYP enzymes and P-glycoprotein. Med Lett Drugs Ther 2013; 55:e44.
  3. Approximate WAC. WAC = wholesaler acquisition cost or manufacturer’s published price to wholesalers; WAC represents a published catalogue or list price and may not represent an actual transactional price. Source: AnalySource® Monthly. January 5, 2015. Reprinted with permission by First Databank, Inc. All rights reserved. ©2015. www.fdbhealth.com/policies/drug-pricing-policy.
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