The aim of this study is observation of effectiveness and side effect of patients with schizophrenia who will switch the antipsychotics from risperidone long acting injection to paliperidone palmitate.

In this study, investigators are going to enroll the patients who will switch the risperidone long acting injection to paliperidone palmitate. And investigators will examine the effectiveness and side effect of paliperidone palmitate. In addition, effectiveness and side effect related variables will be studied.

Inclusion Criteria:

• Age: 18 ~ 65
• Patient with schizophrenia according to DSM-IV criteria
• Patient have signed on the informed consent, and well understood the objective and procedure of this study.
• Maintenance therapy more than 6 months with Risperidone Long Acting Injection monotherapy or other with concomitant antipsychotics, and stable dose of Risperidone Long Acting Injection was maintained 8 weeks more. The stable dose of other antipsychotics has been maintained 8 months and more.
• Patient wants to switch antipsychotics to Paliperidone Palmitate.
• PANSS total score ≤ 80
• Each score of conceptual disorganization(P2), hallucinatory behavior(P3), Suspiciousness/persecution(P6), unusual thought content(G9)in PANSS ≤ 4
• Competent patient who is manage to answer the questionnaires.
• In case of female at child-bearing age, consent to use appropriate contraceptive methods(oral pill, contraceptive injection, intrauterine device, double barrier method and contraceptive patch) during entire duration of this study.

Exclusion Criteria:

• No history of antipsychotics use.
• Past history of NMS.
• Allergy or hypersensitivity to Risperidone or Paliperidone ER.
• Concomitant antipsychotics was oral Risperidone or Paliperidone ER.
• Initiating or dose-changing of SSRI, MAOI, TCA within 2 months(maintenance is allowed if those have been stable for at least 30days prior to study entry and would not be any dose changes during the study)
• Initiating of Lithium, Valproic acid, Carbamazepine, Topiramate, Lamotrigine or other mood stabilizer within 2months (maintenance is allowed).
• Patient who is supposed to be impossible to participate to this study due to clinical risk of suicide or aggressive behavior based on clinician's opinion.
• Current substance dependence(DSM-IV) or past history of dependence (more than 6months)
• Significant biochemical or hematological abnormality or abnormal finding of urinalysis, based on clinician's opinion.
• History of cardiac disease which predispose to QT prolongation(sick sinus, complete AV block, CHF, ventricular tachycardia, hypokalemia or hypocalcemia) or current medication of QT prolonging drugs
• Pregnant or breast-feeding female patient.
• History of participating to other investigational drug trial within 1month prior to screening.
• Investigator or employee at clinical trial center, personnel related to investigator or trial center on this or other study, or family of employee or investigator

Patients with schizophrenia who would be switched to Paliperidone Palmitate from Risperidone Long Acting Injection