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Voriconazole

Voriconazole is a broad-spectrum antifungal agent of triazole group. The triazoles (fluconazole, itraconazole etc.) were developed in order to increase the spectrum of anti fungal activity  and reduce the side effects associated with the imidazoles.It is a second-generation synthetic derivative of fluconazole, with enhanced potency and a broad spectrum of activity.

Mechanism of action:

Voriconazole acts by inhibiting the enzyme demethylase (Lanosterol 14 α-demethylase is a cytochrome P450 enzyme that converts lanosterol to cholesterol.) This blocks the demethylation of lanosterol to ergosterol, the principal sterol of fungal membranes. This leads to disruption of fungal cell membrane and inhibition of  fungal cell growth.

Pharmacokinetics:

  1. Voriconazole is available for intravenous and oral administration.
  2. Voriconazole has 96% bioavailablity. Peak plasma concentration is reached 2-3 hours of oral administration.
  3. Voriconazole penetrates tissues well, including the CNS.
  4. Intraocular penetration of the drug is good.
  5. Voriconazole for intravitreal injection is available as white lyophilized powder. It is available as 200 mg of voriconazole presented in a 30-mL clear glass vial and it required reconstitution and dilution. The powder is reconstituted with 19 mL of distilled water to obtain 20 mL of clear concentrate containing 10 mg/mL voriconazole. Intravitreal administration is achieved as single injection of 0.1 mL which contains  50 micrograms.
  6. Voriconazole was reported to be injected intracamerally, at a dose of 50  microg/0.1 mL.
  7. The drug is primarily metabolized in liver.

Topical

Subconjunctival

Intravitreal

Intravenous

Oral

1% Solution (not available commercially)

NA

50  µg/0.1 mL.

3mg /kg/hour over 1–2 hour

200mg 12 hourly

 

Spectrum of  susceptible organisms :

Voricoanazole has broad spectrum of fungistatic action against most yeast and many filamentous fungi. Voriconazole has been approved for treatment of invasive aspergillosis and has replaced amphotericin B as the treatment of choice for this indication.
Voriconazole has been recommended from infections from P. boydii,S. apiospermeen, and Fusarium infections in patients intolerant or with refractory infections to other agents.

Side effects:

Side effects are similar to those of the other azoles.
Transient visual disturbance that occurs within 30 minutes of administration is a unique feature of the drug.

Drug interaction:

Voriconazole interacts with various drugs as it is metabolized by hepatic cytochrome P450 enzymes.

  1. Administration is contraindicated with sirolimus, rifampin, rifabutin, and ergot alkaloids
  2. Require dose adjustments and/or monitoring when coadministered with cyclosporine, tacrolimus, omeprazole, and phenytoin.

Statutory Warning

Materials / Informations provided here are for educational purpose only ; and not to be used for medical advice, diagnosis or treatment