[Drug interactions between coumarin derivatives and antimycotics: also with topical antifungal agents].

The imidazole derivative miconazole is often used to treat fungal infections of the skin, mouth and gastrointestinal tract. Used concomitantly with coumarin derivatives, it may enhance their anticoagulant effects by inhibiting the CYP2C9 isoenzyme; an interaction which has been well described for oral and vaginal administrations of miconazole. In daily practice, however, cutaneous formulations can also cause clinically relevant drug interactions after having been absorbed through the skin. We describe 4 patients in whom topically applied miconazole enhanced the effect of coumarin derivatives. These cases concern reports received by the Netherlands Pharmacovigilance Centre Lareb between April 2001 and April 2012.