[Severe neurotoxicological reaction by combined treatment with vincristine and fluconazole].

We describe the case of a woman, aged 41 years, who received a combination chemotherapy including vincristine, doxorubicine, ifosfamide and etoposide due to Ewings sarcoma. She was treated prophylactic with fluconazole to prevent oral candidosis. Unexpectedly, she developed severe neurotoxic side effects. Treatment with multiple substrates of cytochrome P450 3A4 combined with inhibition of the enzyme by fluconazole impairs metabolism and thereby increase plasma concentrations of vincristine, which is considered to be the main reason for the neurotoxic side effects.