[The effect of oxcarbamazepine on the clinical effectiveness of dopamine agonists in the treatment of prolactinoma].

The CYP450 enzyme family plays a very important role in the biotransformation of many drugs with a different chemical structure. Therefore, the inhibition or induction of CYP enzymes may be responsible for the development of numerous drug interactions. Moreover, a peculiarity of constitution causes that some persons in particular situations may respond differently to a drug or treatment than do most people. In this article, we show a case of a young woman diagnosed with prolactinoma who was initially successfully treated with bromocriptine. Two years later she developed epilepsy secondary to brain trauma and as a result, she started receiving oxcarbamazepine treatment. Unfortunately, the treatment led to a deterioration of prolactinoma control. To normalize plasma prolactin levels, bromocriptine dose had to be increased and then replaced, initially with cabergoline and later with quinagolide. Only the latter drug effectively reduced plasma prolactin levels and tumor size. This case shows for the first time the existence of a drug interaction between dopamine agonists and any anti-epileptic drug in patients with prolactinoma.