Atypical antipsychotics are frequently associated with increased risk of weight gain as side effect.

To compare body weigh alteration in psychotic disorder patients undergoing atypical neuroleptics therapy.

This study included 37 patients with mean age of 35,14 ± 1,57 years old, enrolled in a public mental health service with psychotic disorders related to the use of illicit drugs and schizophrenia.

Patients treated with atypical neuroleptics such as olanzapine (11) 0,28 mg/kg/day, clozapine (7) 1,56 mg/kg/day and risperidone (10) 0,031 mg/kg/day, were evaluated. Haloperidol (9) 0,072 mg/kg/day, as typical neuroleptics was also studied. Neuroleptics’ treatment period was 126,97 ± 20,93 days and the patients inicial body weight mean was 67,63 ± 2,13 kg.

Increase of body weight of 1,79 ± 0,72 kg was observed for patients receiving haloperidol, compared with olanzapine 10,37 ± 1,74 kg, clozapine 3,6 ± 2,10 kg and risperidone 1,21 ± 0,90 kg in the end of evaluation period.

These increase of body weight calculated in g/day were 31,68 ± 1,83 g/day for haloperidol, 99,54 ± 25,55 g/day for olanzapine, 27,44 ± 13,35 g/day for clozapine and 13,11 ± 1,40g/day for risperidone.

Increase of body weight index (BWI) at the end of the period of analysis was 0,66 ± 0,25 for haloperidol, 3,59 ± 0,63 for olanzapine, 1,52 ± 0,90 for clozapine and 0,40 ± 0,35 for risperidone.

These BWI increases identified per day were 0,011 ± 0,0038 for haloperidol, 0,034 ± 0,0085 for olanzapine, 0,011 ± 0,0057 for clozapine and 0,0039 ± 0,0055 for risperidone.

Although haloperidol, olanzapine, clozapine and risperidone act blocking serotonin receptors conducting to body weight gain, they probably act with different intensity degree of blockage.