Diflunisal

Teratogenic Effects. Pregnancy Category C.

A dose of 60 mg/kg/day of diflunisal (equivalent to two times the maximum human dose) was maternotoxic, embryotoxic, and teratogenic in rabbits. In three of six studies in rabbits, evidence of teratogenicity was observed at doses ranging from 40 to 50 mg/kg/day. Teratology studies in mice, at doses up to 45 mg/kg/day, and in rats at doses up to 100 mg/kg/day, revealed no harm to the fetus due to diflunisal. Aspirin and other salicylates have been shown to be teratogenic in a wide variety of species, including the rat and rabbit, at doses ranging from 50 to 400 mg/kg/day (approximately one to eight times the human dose). Animal reproduction studies are not always predictive of human response. There are no adequate and well controlled studies with diflunisal in pregnant women. Diflunisal should be used in pregnancy only if the potential benefit justifies the potential risk to the fetus.

Labor and Delivery

In rat studies with NSAIDs, as with other drugs known to inhibit prostaglandin synthesis, an increased incidence of dystocia, delayed parturition, and decreased pup survival occurred. The effects of diflunisal on labor and delivery in pregnant women are unknown.

Diflunisal is excreted in human milk in concentrations of 2-7% of those in plasma. Because of the potential for serious adverse reactions in nursing infants from diflunisal, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.