The Effect of Paliperidone Palmitate in Schizophrenia

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. * PANSSS total score \<120 * each Score of disorganized thought, paranoia hallucinatory behavior, abnormal tbought contests \< 16 * three different groups ( other antipsychotics refractory schizophrenia patitents : CGI\> 4 chronic akathisia : DIEPSS overall severity \>1, at least 1 month lasting symptoms poor compliance schizophrenia : CRS \<3) * 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 prescription * History of NMS(Neuroleptic malignant syndrome) * Allergic reaction or hypersensitive reaction of risperidone or paliperidone ER * clozapine medication within 1 month before screening * SSRI, MAOI, TCA medication within 2 months * Lithium, valproic acid, carbamazepine, topiramate, lamotrigine medication starting within 2 months * 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 or previous history of drug depedence according to DSM-IV * Pregnant or breast-feeding female patient * Significant biochemical or hematological abnormality or abnormal finding of urinalysis, based on clinician's opinion * history of cardiac disease, which is related to QT prolongation(sick sinus, complete AV block, CHF, ventricular tachycardia, hypokalemia or hypocalcemia) * 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