Voriconazole

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Voriconazole
Voriconazole structure.svg
Voriconazole ball-and-stick.png
Systematic (IUPAC) name
(2R,3S)-2-(2,4-Difluorophenyl)-3-(5-fluoropyrimidin-4-yl)-1-(1H-1,2,4-triazol-1-yl)butan-2-ol
Clinical data
Trade names VFEND
AHFS/Drugs.com monograph
MedlinePlus a605022
Licence data EMA:Link, US FDA:link
Pregnancy cat. D
Legal status Prescription only
Routes IV, oral
Pharmacokinetic data
Bioavailability 96%
Protein binding 58%
Metabolism Hepatic cytochrome P450 enzymes CYP2C19, CYP2C9, CYP3A4
Half-life Dose-dependent
Identifiers
CAS number 137234-62-9 YesY
ATC code J02AC03
PubChem CID 71616
DrugBank DB00582
ChemSpider 64684 YesY
UNII JFU09I87TR YesY
KEGG D00578 YesY
ChEBI CHEBI:10023 YesY
ChEMBL CHEMBL638 YesY
Chemical data
Formula C16H14F3N5O 
Mol. mass 349.311 g/mol
 YesY (what is this?)  (verify)

Voriconazole (vor-i-KON-a-zole, brand name Vfend, Pfizer) is a triazole antifungal medication that is generally used to treat serious, invasive fungal infections. These are generally seen in patients who are immunocompromised, and include invasive candidiasis, invasive aspergillosis, and certain emerging fungal infections.[citation needed]

Indications[edit]

Invasive aspergillosis[edit]

Vfend 200mg oral tablet

Voriconazole has become the new standard of care in the treatment of invasive aspergillosis, which may occur in immunocompromised patients, including allogeneic BMT, hematologic cancers, and solid organ transplants. This is based on the results of a large, randomized study in which voriconazole proved superior to amphotericin B with 53% complete or partial response, compared with 32% for amphotericin B.[1]

Importantly, voriconazole also offered a 22% greater survival benefit over amphotericin B, with 71% of voriconazole patients still alive at week 12. Only 13% of patients who received initial therapy with voriconazole died from invasive aspergillosis, compared with 29% of patients who initially received amphotericin B. Voriconazole was also better tolerated than amphotericin B, with significantly fewer serious adverse effects and a longer duration of therapy. Note that the design of these studies has been called into question, and some still consider (liposomal) amphotericin B as the drug of choice.[2] For multiple site or CNS aspergillosis a combination therapy of voriconazole and caspofungin should be considered. It is also the recommended treatment for the CNS fungal infections transmitted by epidural injection of contaminated steroids.[3]

With fewer patients having to switch from initial voriconazole than amphotericin B or its lipid formulations because of intolerance or insufficient response, and limited efficacy of salvage therapy with other licensed antifungals, the importance of effective initial therapy has been demonstrated.[4]

Candidemia[edit]

Voriconazole has proven to be as effective as a regimen of IV amphotericin B followed by oral fluconazole in patients with culture-proven candidemia. Voriconazole cleared Candida from the bloodstream as quickly as amphotericin B (median 2 days) and showed a trend toward better survival. Voriconazole was also associated with fewer serious adverse events and cases of renal toxicity, but a higher incidence of visual disturbances.[5]

Voriconazole was also proven to offer similar, near-complete efficacy to fluconazole in the treatment of esophageal candidiasis.[6]

Empirical antifungal therapy[edit]

A study compared Voriconazole use to that of amphotericin B in the treatment of patients with unresolved fever despite broad-spectrum antibiotic therapy who are at risk for breakthrough fungal infections. While overall success rates were 26.0% for voriconazole and 30.6% for liposomal amphotericin B, there were significantly fewer breakthrough infections with voriconazole, particularly in the patients at highest risk. This study found similar fewer severe reactions and nephrotoxicity but more transient visual disturbances and hallucinations. Voriconazole was also associated with a shorter duration of hospitalization. The authors of this study concluded, "This study demonstrates that voriconazole, a second-generation triazole, is an appropriate agent for empirical antifungal therapy and that its use may reduce the frequency of proven breakthrough fungal infections, preserve renal function, and reduce the frequency of acute infusion-related toxic effects. Formulations of amphotericin B have been the standard of empirical antifungal therapy for nearly 20 years. As this study shows, a second-generation triazole can be used in lieu of amphotericin B for early anti fungal therapy."[7]

Efficacy against emerging fungal pathogens[edit]

In collected case studies, voriconazole has also been proven effective against a number of other serious fungal pathogens. This includes infections by Fusarium spp and Scedosporium apiospermum (asexual form of Pseudallescheria boydii). Although infrequently seen, these molds are emerging as more common and deadly causes of fungal infection in seriously immunocompromised patients, and the development of voriconazole has been an important advance in their treatment as they are generally resistant to other antifungal agents (including amphotericin B). Voriconazole is the first and only drug ever specifically indicated for their treatment by the FDA. Voriconazole has also been used to treat severe fungal corneal infection [1]

Pharmacology[edit]

Voriconazole is well absorbed orally with a bioavailability of 96%, allowing patients to be switched between intravenous and oral administration.

Being metabolized by hepatic cytochrome P450, voriconazole interacts with some drugs. Administration is contraindicated with some drugs (such as sirolimus, rifampin, rifabutin, and ergot alkaloids) and dose adjustments and/or monitoring when coadministered with others (including cyclosporine, tacrolimus, omeprazole, and phenytoin). Voriconazole may be safely administered with cimetidine, ranitidine, indinavir, macrolide antibiotics, mycophenolate, and prednisolone.

Because voriconazole is metabolized by the liver, the dose should be halved in patients with mild to moderate hepatic impairment (Child-Pugh score A or B). There is no data available for patients with severe hepatic impairment (Child-Pugh C).

No dose adjustment is necessary for renal impairment or advanced age, but children seem to clear voriconazole faster than adults and drug levels may need monitoring.[8]

Side effects[edit]

The most common side effects associated with voriconazole include transient visual disturbances, fever, rash, vomiting, nausea, diarrhea, headache, sepsis, peripheral edema, abdominal pain, and respiratory disorder.

Unlike most adverse effects, which are similar to other azole antifungal agents, visual disturbances (such as blurred vision or increased sensitivity to light) are unique to voriconazole. These have been reported by more than 30% of patients in clinical trials. They generally occur approximately one-half hour after administration, and last approximately 30 minutes. In some patients they may go away after continued use. Studies have shown that there is no damage to the eye or long-term effect on vision. However, patients taking voriconazole should be advised against driving at night or other potentially hazardous tasks.

Though rare, there have been cases of serious hepatic reactions during treatment with voriconazole (a class effect of azole antifungal agents). Liver function tests should be evaluated at the start of and during the course of therapy.

Voriconazole is phototoxic. It has been associated with an increased risk of squamous-cell carcinoma of the skin.[9]

Synthesis[edit]

Voriconazole can be synthesized beginning with a keto-ester:[10]

Voriconazole synth.png

References[edit]

  1. ^ Herbrecht R, Denning D, Patterson T, Bennett J, Greene R, Oestmann J, Kern W, Marr K, Ribaud P, Lortholary O, Sylvester R, Rubin R, Wingard J, Stark P, Durand C, Caillot D, Thiel E, Chandrasekar P, Hodges M, Schlamm H, Troke P, de Pauw B; Invasive Fungal Infections Group of the European Organisation for Research and Treatment of Cancer and the Global Aspergillus Study Group (Aug 8, 2002). "Voriconazole versus amphotericin B for primary therapy of invasive aspergillosis". N Engl J Med 347 (6): 408–15. doi:10.1056/NEJMoa020191. PMID 12167683. 
  2. ^ Agarwal R, Singh N (Jul 1, 2006). "Voriconazole versus amphotericin B for primary therapy of invasive aspergillosis". Am J Respir Crit Care Med 174 (1): 102. PMID 16793999. 
  3. ^ http://www.cdc.gov/hai/outbreaks/clinicians/guidance_cns.html
  4. ^ Patterson T, Boucher H, Herbrecht R, Denning D, Lortholary O, Ribaud P, Rubin R, Wingard J, DePauw B, Schlamm H, Troke P, Bennett J (Nov 15, 2005). "Strategy of following voriconazole versus amphotericin B therapy with other licensed antifungal therapy for primary treatment of invasive aspergillosis: impact of other therapies on outcome". Clin Infect Dis 41 (10): 1448–52. doi:10.1086/497126. PMID 16231256. 
  5. ^ Kullberg B, Sobel J, Ruhnke M, Pappas P, Viscoli C, Rex J, Cleary J, Rubinstein E, Church L, Brown J, Schlamm H, Oborska I, Hilton F, Hodges M (22 Oct 2005-28). "Voriconazole versus a regimen of amphotericin B followed by fluconazole for candidaemia in non-neutropenic patients: a randomised non-inferiority trial". Lancet 366 (9495): 1435–42. doi:10.1016/S0140-6736(05)67490-9. PMID 16243088. 
  6. ^ Ally R, Schürmann D, Kreisel W, Carosi G, Aguirrebengoa K, Dupont B, Hodges M, Troke P, Romero A (Nov 1, 2001). "A randomized, double-blind, double-dummy, multicenter trial of voriconazole and fluconazole in the treatment of esophageal candidiasis in immunocompromised patients". Clin Infect Dis 33 (9): 1447–54. doi:10.1086/322653. PMID 11577374. 
  7. ^ Walsh T, Pappas P, Winston D, Lazarus H, Petersen F, Raffalli J, Yanovich S, Stiff P, Greenberg R, Donowitz G, Schuster M, Reboli A, Wingard J, Arndt C, Reinhardt J, Hadley S, Finberg R, Laverdière M, Perfect J, Garber G, Fioritoni G, Anaissie E, Lee J; National Institute of Allergy and Infectious Diseases Mycoses Study Group (Jan 24, 2002). "Voriconazole compared with liposomal amphotericin B for empirical antifungal therapy in patients with neutropenia and persistent fever". N Engl J Med 346 (4): 225–34. doi:10.1056/NEJM200201243460403. PMID 11807146. 
  8. ^ Smith J, Safdar N, Knasinski V, Simmons W, Bhavnani S, Ambrose P, Andes D (April 2006). "Voriconazole therapeutic drug monitoring". Antimicrob Agents Chemother 50 (4): 1570–2. doi:10.1128/AAC.50.4.1570-1572.2006. PMC 1426935. PMID 16569888. 
  9. ^ Epaulard O, Saint-Raymond C, Villier C, Charles J, Roch N, Beani JC, Leccia MT (2010 Sep). "Multiple aggressive squamous cell carcinomas associated with prolonged voriconazole therapy in four immunocompromised patients". Clin Microbiol Infect 16 (9): 1362–1364. 
  10. ^ Fromtling, R. O.; Drugs Future 1996, 21, 266