It is well known the difficulties found in making most psychotic patients follow a long-lasting oral treatment.To overcome this problem, injected drugs were developed over the last decades. One of the main side effects of these drugs is weight gain. To asess its importance in the newest long –acting injection of risperidone, a retrospective study was developed.

Clinical records of 61 patients with injected risperidone were reviewed, obtaining data about pre-treatment weight and weight after a year of bimensual injections. Patients with eating disorders or organic pathology were excluded. Other variables were recorded: doses, other injected treatments in the previous year and the weight gain, and coadyuvant oral treatment of neuroleptics during the studied period.

No statistically significant weight differences were found during the first year of treatment (p>0.05). When considering doses, or patients with coadyuvant therapy of low-dose neuroleptics, no difference was found either (p>0.05).

23 of these patients followed another long-lasting injected treatment for at least a year before sweeping to risperidone. A bigger weight gain was was found in that previous period of time than in the following year with risperidone (p=0.037).

Compliance to treatment is one of the keys to success in schyzophrenia management. Side effects may hazard this compliance: injected long-lasting risperidone seems to minimize weight gain in these patients, compared to previous injected drugs, making it easier to follow these prolonged treatments.