Fluconazole Review Article
Fluconazole is used to prevent both the systemic as well as the superficial fungal infections. It is commonly marketed under the brand name Trican or Diflucan.
Mechanism of action
Like other imidazole- and triazole-class antifungals, fluconazole inhibits the fungal cytochrome P450 enzyme 14¦?-demethylase. Mammalian demethylase activity is much less sensitive to fluconazole than fungal demethylase. This inhibition prevents the conversion of lanosterol to ergosterol, an essential component of the fungal cytoplasmic membrane, and subsequent accumulation of 14¦?-methyl sterols. Fluconazole is primarily fungistatic, however may be fungicidal against certain organisms in a dose-dependent manner. Interestingly, when fluconazole was in development at Pfizer it was decided early in the process to avoid producing any chiral centers in the drug so that subsequent synthesis and purification did not encounter difficulties with enantiomer separation and associated variations in biological effect. A number of related compounds were found to be extremely potent teratogens and subsequently discarded. Continue reading...
Fluconazole generic (generic - what is it?)
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Fluconazole can be used for both the prophylaxis and treatment of fungal infections including Tinea corporis, Candidiasis, tinea pedis, tinea cruris, Cryptococcal meningitis, Onychomycosis. It can also be used as the first line treatment of Coccidioidomycosis, Histoplasmosis and Cryptococcosis.
Dosage, varies with indication and between patient groups, ranging from: a two week course of 150 mg/day for vulvovaginal candidiasis, to 150?C300 mg once weekly for resistant skin infections or some prophylactic indications. 500?C600 mg/day may be used for systemic or severe infections, and in urgent infections such as meningitis caused by yeast 800 mg/day have been used. Pediatric doses are measured at 6-12 mg/kg/d . A loading dose will be indicated when entering a daily dosage schedule, for example a loading dose of 200 mg on the first day is commonly used with 150 mg/day following that.
Fluconazole is contraindicated in the patients who are hypersensitive to it. It is also contraindicated in the patients who are taking the terfenadine and quinidine. Similarly fluconazole is also contraindicated in the pregnancy.
Fluconazole therapy has been associated with QT interval prolongation, which may lead to serious cardiac arrhythmias. Thus it is used with caution in patients with risk factors for prolonged QT interval such as electrolyte imbalance or use of other drugs which may prolong the QT interval (particularly cisapride).
There are no adequate studies of fluconazole on the pregnant women. In a few published case reports it was revealed that when the fluconazole is used during the pregnancy especially in high doses then it has the damaging effect on the fetus. The treatment with the high doses i.e. about 400-800 mg/day of fluconazole during the pregnancy (first trimester) may produce the birth defects in infants thus the use of fluconazole during pregnancy should be avoided.
Fluconazole should be administered with caution in patients having proarrhythmic conditions. It should also be used with caution in patients having renal dysfunction.
Fluconazole has also rarely been associated with severe or lethal hepatotoxicity and liver function tests are usually performed regularly during prolonged fluconazole therapy. Additionally, it is used with caution in patients with pre-existing liver disease.
High concentrations of fluconazole have been detected in human breast milk from patients receiving fluconazole therapy, thus its use is not recommended in breastfeeding mothers.
Adverse drug reactions associated with fluconazole therapy include:
Common: rash, headache, dizziness, nausea, vomiting, abdominal pain, diarrhea, and/or elevated liver enzymes
Infrequent: anorexia, fatigue, constipation
Rare: oliguria, hypokalaemia, paraesthesia, seizures, alopecia, Stevens-Johnson syndrome, thrombocytopenia, other blood dyscrasias, serious hepatotoxicity including hepatic failure, anaphylactic/anaphylactoid reactions
Very rare: prolonged QT interval, torsades de pointes.
Overdose of the fluconazole leads towards the paranoid behavior and hallucination. If the overdose of the fluconazole occurs then immediately symptomatic treatment is given. In the symptomatic treatment gastric lavage is carried out and supportive therapy is given to the patient.
In a study (Moorhead et al., 2011) it has been observed that the fluconazole can treat the breast and nipple thrush. In this study the women suffering from nipple and breast Candida were treated with the 150mg capsules of the fluconazole and it was observed in the study that the women having severe breast pain needed more than 3 capsules than the women with less severe pain.
In another study (Cordeiro Rde et al., 2011) it has been observed that the cotrimoxazole enhances the in vitro susceptibility of Coccidioides posadasii strains to antifungals like itraconazole, fluconazole, amphotericin B and voriconazole. It was also observed in this study that the cotrimoxazole itself inhibited the strains of Coccidioides posadasii.
In another study (Liu et al., 2011) it was also found that the corneal permeability of the fluconazole eye drops can be increased by the permeability enhancers like menthol and borneol.
A study (Ascher et al., 2011) has also revealed that when the infants suffering from invasive candidiasis were treated with the amphotericin B lipid products then their mortality rate was high as compared to the infants treated with the fluconazole.
In a study (Lass-florl at al., 2011) different antifungal drugs are studied for the different types of fungal infections. In this study it was observed that the fluconazole plays an excellent role in the prophylaxis, empirical therapy and the treatment of both invasive and superficial yeast fungal infections. In this study it was also observed that the voriconazole can be strongly recommended for the pulmonary invasive aspergillosis. Similarly itraconazole plays an important role in the treatment of the fungal skin and nail infections as well as helpful in the treatment of the dematiaceous fungi and endemic mycoses. In the same study it was also observed that the posaconazole may prove helpful in the treatment of the invasive aspergillosis and can also be used prophylactically in patients with neutropenia and haematopoietic stem-cell transplant recipients.
Fluconazole has the drug-drug interactions with the different types of drugs. Hypoglycemic is precipitated by the concomitant use of fluconazole with the oral hypoglycemic agents. Fluconazole increases the plasma concentration of phenytoin, theophylline, halofantrine and midazolam when used in combination with these drugs.
Dosage forms, Dose and administration
Fluconazole is available in different dosage forms. It is available in the form of tablets for the oral administration. It is also available in the form of oral suspension, and in the form of solution for the intravenous administration.
In the tablet dosage form it is available in the dose of 50,100,150 or 200 mg while in the case of oral suspension it is available in the dose of 10mg or 40 mg per ml. Similarly in case of injection it is available in the dose of 2mg per ml.
In case of Vaginal candidiasis fluconazole is given as a single oral dose of 150mg. While in case of oropharyngeal candidiasis and esophageal candidiasis first dose of 200mg of fluconazole is given on the first day then 100mg is given once daily. Similarly in case of Systemic Candida infections fluconazole dose of up to 400mg is used. In case of urinary tract infections and peritonitis daily dose of up to 50 to 200mg is given. For the treatment of the acute cryptococcal meningitis the recommended daily dose is 400mg on the first day followed by the 200mg once daily. The usual recommended dose for the prophylaxis in patients undergoing bone marrow transplantation is 400mg once daily.
Ascher SB, Smith PB, Watt K, Benjamin DK, Cohen-Wolkowiez M, Clark RH, Benjamin DK Jr, Moran C., 2011, Antifungal Therapy and Outcomes in Infants with Invasive Candida Infections, Pediatr Infect Dis J, Dec 20. [Epub ahead of print]
Borgers M, 1980, Mechanism of action of antifungal drugs with special reference to the imidazole derivatives, Rev Inf Dis, 2:520-34.
Cordeiro Rde A, Astete-Medrano DJ, Marques FJ, Andrade HT, Perdig?o Neto LV, Tavares JL, Lima RA, Patoilo KK, Monteiro AJ, Brilhante RS, Rocha MF, Camargo ZP, Sidrim JJ., 2011, Cotrimoxazole enhances the in vitro susceptibility of Coccidioides posadasii to antifungals, Mem Inst Oswaldo Cruz, 106(8):1045-8.
Diflucan (Australian Approved Product Information), 2004, Pfizer Australia Pvt Ltd.
Lass-Fl?rl C., 2011, Triazole antifungal agents in invasive fungal infections: a comparative review, Drugs, 71(18):2405-19. doi: 10.2165/11596540-000000000-00000.
Liu J, Fu S, Wei N, Hou Y, Zhang X, Cui H ., 2011, The effects of combined menthol and borneol on fluconazole permeation through the cornea ex vivo, Eur J Pharmacol, Dec 16. [Epub ahead of print]
Moorhead AM, Amir LH, O'Brien PW, Wong S., 2011, A prospective study of fluconazole treatment for breast and nipple thrush, Breastfeed Rev, 19(3):25-9.
Fluconazole Review Article