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What is Posaconazole?

Mar 29，2022

DESCRIPTION

Posaconazole (Nofaxil, SCH-56592) is a triazole derivative with a chemical structure similar to itraconazole. The structures of both azoles contain extended piperazine-phenyl-triazole side-chains, but posaconazole is composed of a furan ring with fluorine substituted for chlorine. Like other compounds in the azole class, posaconazole disrupts fungal ergosterol biosynthesis through inhibition 14a-lanosterol demethylation. Currently, the only available preparation is an immediate-release oral suspension containing polysorbate 80 as an emulsifying agent.

Posaconazole demonstrates potent activity against Candida spp., Cryptococcus spp., dimorphic fungi, and filamentous fungi, including Aspergillus as well as Zygomycetes. It has Food and Drug Administration (FDA) approval for prophylaxis of invasive fungal infection in hematopoietic stem cell transplant recipients with graft-versus-host disease (GVHD) and patients with hematologic malignancies and prolonged neutropenia. It is also FDA approved for treatment of oropharyngeal candidiasis. In Europe, posaconazole is additionally approved for the following fungal infections refractory to amphotericin B and/or itraconazole: aspergillosis, fusariosis, chromoblastomycosis, mycetoma, and coccidioidomycosis.

MECHANISM OF DRUG ACTION

Posaconazole is a triazole drug which inhibits cytochrome P450- dependent C14-a sterol demethylase, a key enzyme in the biosynthesis of fungal ergosterol. Disruption of this step results in depletion of ergosterol from the fungal cell membrane. As the ergosterol content decreases and methylated sterol intermediates accumulate, membrane permeability increases and growth is inhibited. If severe, these changes may result in cell death.

TOXICITY

Similar to the other drugs from the triazole class, posaconazole appears to be well-tolerated. The most common adverse effects are mild and include gastrointestinal complaints, rash, facial flushing, dry mouth, and headache. Gastrointestinal symptoms (diarrhea, nausea, and vomiting) were reported in 15% of patients receiving posaconazole Table 136.4 Potential posaconazole drug interactions. Posaconazole may increase drug concentration Antiarrhythmics – quinidine Antibiotics – rifabutin Antiepileptics – phenytoin Antimalarials – halofantrine Antipsychotics – pimozide Antiretrovirals – etravirine Antihistamine – astemizole (off market), terfenadine (off market) Benzodiazepines – midazolam Calcium channel blockers – amlodipine, diltiazem, felodipine, lercanidipine, nifedipine, nisoldipine, nitrendipine, verapamil Ergot alkaloids – dihydroergotamine, ergoloid mesylates, ergonovine, ergotamine, methylergonovine, methysergide Immunosuppressants – ciclosporin, sirolimus, tacrolimus Serotonic receptor antagonists – cisapride (off market) Statins – atorvastatin, lovastatin, simvistatin Vinca alkaloids – vinblastine, vincristine, vincristine liposome, vinorelbine Drugs that may decrease posaconazole concentration Antiepileptics – phenytoin H2-blockers – cimetidine 1866 Systemic Azoles for persistent febrile neutropenia or refractory invasive fungal infection. Rash or other skin disorders occurred in 3% of these patients, but did not result in discontinuation of the drug. Like other azoles, hepatic toxicity has been infrequently described. Therefore, monitoring of liver function tests is recommended before and during treatment. Very rarely, prolongation of QT or QTc interval and torsades de pointes have been reported.

Posaconazole is pregnancy category C and has not been studied in pregnant women. Administration of another azole, fluconazole, during pregnancy was associated with congenital birth defects, including craniofacial, skeletal, and cardiac anomalies. Posaconazole is not recommended for pregnant women or nursing mothers unless the potential benefit outweighs the risk.

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