[Dose-dependent pellagroid skin reaction caused by carbamazepine]

A 11-year-old girl suffering from grand mal epilepsy underwent antiepileptic therapy with carbamazepine (600 mg/daily). Two weeks after increasing the dose (900 mg/day) she suddenly developed relatively sharply limited, sunburn-like brown reddish macular lesions with central scaling and partly hyperkeratotic areas on the hands, feet, face, knees, gluteal and axillar regions. Otherwise no health disorders were found; in particular no neurological or gastrointestinal symptoms occurred. After reduction of the doses (450 mg/day) these skin lesions faded away. With exception of elevated serum levels of carbamazepine, nicotinamide and vitamin B6, all blood tests were in normal range. Interactions of carbamazepine with the vitamin B6- nicotinamide metabolism are the reason for these previously undescribed cutaneous side effects in connection with carbamazepine therapy. The present case demonstrates a toxic, non-allergic reaction during carbamazepine treatment with pellagroid skin symptoms.