The US Food and Drug Administration (FDA) has warned that high doses of the antifungal drug, Diflucan (fluconazole), may cause birth defects in children whose mothers were treated with the drug during the first trimester of pregnancy.
The risks affect mothers who have taken high doses (400-800 mg/day) but do not appear to affect those who were treated with a single, low dose of fluconazole 150 mg for vaginal yeast infection (candidiasis), FDA confirmed.
As a result, the pregnancy category for fluconazole indications (other than vaginal candidiasis) has been changed from category C to category D, meaning that there is positive evidence of human foetal risk based on human data but the potential benefits from use of the drug in pregnant women with serious or life-threatening conditions may be acceptable despite its risks.
The FDA published the following advice for healthcare professionals:
• The pregnancy category for a single 150 mg dose of fluconazole for vaginal candidiasis is category C based on data from animal studies that showed an adverse effect on the foetus. There are no adequate and well-controlled studies of fluconazole in pregnant women. Available human data do not suggest an increased risk of congenital anomalies following a single maternal dose of 150 mg.
• The pregnancy category for fluconazole use for indications other than vaginal candidiasis is now category D. A few published case reports describe a rare pattern of distinct congenital anomalies in infants exposed in utero to high-dose maternal fluconazole (400-800 mg/day) during most or all of the first trimester.
• The features seen in these infants include brachycephaly, abnormal facies, abnormal calvarial development, cleft palate, femoral bowing, thin ribs and long bones, arthrogryposis, and congenital heart disease. These effects are similar to those seen in animal studies.
• If fluconazole is used during pregnancy, or if a patient becomes pregnant while taking fluconazole, the patient should be informed of the potential risk to the foetus.