Psychopharmacology A patient with prolonged hyperprolactinemia caused by clozapine: a case report

Prolactin (PRL) is a pituitary hormone synthesized by lactotroph cells located in anterior pituitary gland, whose release is inhibited by dopamine. Clozapine has a mild effect on nigrostriatal and tuberoinfundibular D2 receptors. Clozapine attaches to D2 receptors loosely, and causes a transient and low level occupation of D2 receptors, and this has been proposed as the underlying mechanism of low risk of hyperprolactinemia (HP) and extrapyramidal system symptoms (EPS) caused by clozapine. Mrs. A.B. is a 29-year-old, divorced, mother of one child, housewife. She was married at the age of 18 and got pregnant after 7 months. The first symptoms of schizophrenia had begun during her pregnancy, which were auditory hallucinations and disorganized speech and behavior related to these hallucinations. During this hospitalization, her galactorrhea was noticed, her PRL level was found to be high (4640.68 uIU/ml, normal range 102-496 uIU/ml) and amisulpiride was switched to clozapine. Despite this change, her galactorrhea still continued. Her PRL level was 6117 uIU/ml. A pituitary MR (with contrast) was performed, which showed normal results. An endocrinology consultation was made; it was thought that clozapine (she was receiving 300 mg/day at that moment) was causing her HP, and it was recommended that it was stopped and was switched to quetiapine. Her PRL level was checked twice after switching to quetiapine, which returned to almost normal levels (550.2 uIU/ml), and her galactorrhea stopped. We think that HP in our case was primarily caused by amisulpiride. But we may say that HP and galactorrhea was prolonged by clozapine. Switching to clozapine among other “prolactin-sparing” antipsychotics, is usually recommended after antipsychotic induced HP. Adding or starting aripiprazole can be another management strategy, since it is the first potent D2 partial agonist among antipsychotics. Aripiprazole is called “dopamine regulator” since it acts as a D2 antagonist in hyperdopaminergic condition, but as an agonist in hypodopaminergic conditions.