FDA Puts Strict Limits on Oral Ketoconazole Use

Oral ketoconazole (Nizoral) should never be used as first-line therapy for any type of fungal infection because of the risk of liver toxicity and interactions with other drugs, the FDA said Friday.

The agency ordered a series of label changes and a new medication guide for patients that emphasize the risks, which also include adrenal insufficiency. It noted that the restrictions apply only to the oral formulation, not topical versions.

Late Thursday, the chief advisory body for the FDA’s European counterpart went further. The EU’s Committee on Medicinal Products for Human Use (CHMP) recommended that member nations pull oral ketoconazole from their markets entirely.

Both the FDA and the CHMP cited studies indicating high risks of severe, acute liver injury in patients taking the drug. Studies using the FDA’s adverse event reporting system and a similar database in the U.K. indicated that liver toxicity was more common with oral ketoconazole than with other anti-fungals in the azole class.

The FDA also said that oral ketoconazole “is one of the most potent inhibitors” of the CYP3A4 enzyme. This effect can lead to sometimes life-threatening interactions with other drugs metabolized by CYP3A4, and also to adrenal insufficiency, since the enzyme also catalyzes release of adrenal steroid hormones.

“This accounts for clinically important endocrinologic abnormalities observed in some patients (particularly when the drug is administered at high dosages), including gynecomastia in men and menstrual irregularities in women,” the FDA said.

The only indication for oral ketoconazole still supported by the FDA is for use in life-threatening mycoses in patients who cannot tolerate other anti-fungal medications or when such medications are unavailable.

In such instances, the FDA said, physicians should assess liver function before starting the drug. It is contraindicated in patients with pre-existing liver disease, and patients should be instructed not to drink alcohol or use other potentially hepatotoxic drugs.

Adrenal function should also be monitored in patients using the drug.

The CHMP also indicated the topical formulations of ketoconazole should stay on the market, but it found no basis for keeping the oral form available for any purpose.

“Taking into account the increased rate of liver injury and the availability of alternative anti-fungal treatments, the CHMP concluded that the benefits did not outweigh the risks,” the panel indicated in a statement.

It recommended that physicians stop prescribing oral ketoconazole and that they should review alternatives in patients currently receiving the drug. The committee also said that patients now taking oral ketoconazole “make a non-urgent appointment” with their physicians to discuss their treatment.

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By John Gever, Deputy Managing Editor, MedPage Today