Author: Hon A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand, 2003.
Fluconazole is a triazole medicine used to treat fungal infections. It is effective against a broad spectrum of fungi including:
In New Zealand, fluconazole is available as 50 mg, 150 mg and 200 mg capsules on prescription (Diflucan®). There is also a 2 mg/ml injection for intravenous use. In New Zealand, the Pharmaceutical Schedule subsidy of the capsules requires Specialist recommendation except for single-dose use, which is on general prescription and also available over the counter.
Fluconazole binds to the fungal p450 enzymes and stops the cells making ergosterol, the main component of the cell wall.
Fluconazole is well absorbed orally with or without food. It is widely distributed in body tissues. It takes 22 to 30 hours for half of the medication to be cleared from the bloodstream and may take several days of continuous treatment to reach a steady concentration. The drug is eliminated unchanged in the urine so doses should be reduced if there is kidney disease.
For vulvovaginal candidiasis, a single oral dose of fluconazole 150 mg is usually effective. It can be repeated.
Once-weekly fluconazole is often used off-label to treat toenail fungal infections (onychomycosis).
Larger doses (up to 400 mg daily) are required for systemic infections.
Fluconazole is not normally used in children but doses of 5 mg/kg/day have been safely prescribed for a serious infection.
Fluconazole is generally well tolerated. Occasional side effects include:
Fluconazole should not normally be taken in pregnancy. Use during breast-feeding is not generally recommended, because the drug is found in breast milk.
Unfortunately, fluconazole can interact with other medications.
Fluconazole may increase the concentration of these drugs and enhance their effect:
Rifampicin may slightly decrease the concentration of fluconazole.
Fluconazole is not thought to interact with the oral contraceptive pill.
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