The purpose of this study is to evaluate the efficacy and safety of long acting injectable microspheres of risperidone in participants with schizophrenia (psychiatric disorder with symptoms of emotional instability, detachment from reality, often with delusions and hallucinations, and withdrawal into the self), schizophreniform or schizoaffective disorders (disorders in which there is a loss of ego boundaries or a gross impairment in reality testing with delusions or prominent hallucinations).

This is an open-label (all people know the identity of the intervention), longitudinal (participants are followed over time with continuous or repeated monitoring of risk factors or health-outcomes), non-randomized (a clinical trial in which the participants are not assigned by chance to different treatment groups), single-center study to evaluate the efficacy and safety of long acting microspheres of risperidone in adult participants with schizophrenia, schizophreniform or schizoaffective disorders. The duration of this study will be 12 months and duration of treatment will be 6 months. The study will include 4 visits: Baseline, and 3 follow-up visits including Week 4, 12 and 26. All eligible participants will be treated with risperidone 25 milligram (mg) intramuscular injection (injection of a substance into a muscle) for every two weeks up to 6 months. Participants with persistent symptoms and/or requiring higher doses of antipsychotics (agents that control agitated psychotic behavior, alleviate acute psychotic states, reduce psychotic symptoms, and exert a quieting effect) will be initiated with higher doses of risperidone. Doses will be adjusted according to the response of the treatment. Efficacy and safety of the participants will be primarily evaluated by Positive and Negative Syndromes Scale (PANSS) and Extrapyramidal Symptom Rating Scale (ESRS), respectively. Participants' quality of life and safety will be monitored throughout the study.

Inclusion Criteria:

• Symptomatically stable participants defined as a) participants with treatment on outpatient and inpatient basis for at least 4 weeks before entering the study, and b) Positive and Negative Syndrome Scale (PANSS) Positive Subscale Score less than or equal to (<= ) 3 (1-7), including conceptual disorganization, suspicion, hallucinatory conduct and delirium (state of violent mental agitation)
• Participants under antipsychotic treatment with extrapyramidal symptoms, persistent negative symptoms or lack of adherence defined as irregular administration of medication in the last 2 weeks
• Participants who have given their informed consent in writing, or at least, by their family member or personal representative

Exclusion Criteria:

• Participants taking first antipsychotic treatment in his/her life
• Participants with any other psychotic disorder different to the previously mentioned in the inclusion criteria
• Pregnant or nursing women
• History of neuroleptic malignant syndrome (potentially fatal syndrome associated primarily with the use of antipsychotic drugs and clinical features include diffuse muscle rigidity, tremor, high fever) or current symptoms of tardive dyskinesia (a neurological disorder characterized by involuntary movements of the face and jaw)
• Participants with known intolerance or lack of response to risperidone

All the information generated through services from the Principal Investigator (PI), the Sponsor has the rights to publish the data without previous consent from the PI.

The PI must not publish completely or partially any results from the study, without previous authorization from the Sponsor.