A Positron-Emission-Tomography (PET) Study to Measure the Blockade of Dopamine Receptors (D2) in Specific Areas of the Brain in Relation to the Plasma Concentrations of Paliperidone Extended Release (ER) and Oral Risperidone in Schizophrenia Patients and Healthy Controls
Condition: Schizophrenia
MeSH terms: Schizophrenia
Intervention: Paliperidone ER; Oral risperidone; PET Scan; Oral risperidone; Oral risperidone; Paliperidone ER; Paliperidone ER; Oral risperidone; Paliperidone ER
Intervention description: 9 mg tablet once a day followed by PET scan in approximately 2 hours; 6 mg tablet once a day followed by PET scan in approximately 2 hours; PET Scan; 4 mg tablet once a day followed by PET scan in approximately 24 hours; 4 mg tablet once a day followed by PET scan in approximately 2 hours; 6 mg tablet once a day followed by PET scan in approximately 2 hours; 6 mg tablet once a day followed by PET scan in approximately 24 hours; 6 mg tablet once a day followed by PET scan in approximately 24 hours; 9 mg tablet once a day followed by PET scan in approximately 24 hours
Intervention MeSH terms: Risperidone; Paliperidone Palmitate
Phase: Phase 4
Study type: Interventional
Primary purpose: Treatment
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Enrollment: 2.0
Sex: All
Minimum age: 18 Years
Maximum age: 50 Years
Healthy volunteers: Accepts Healthy Volunteers
Keywords: D2-receptor occupancy; Antipsychotic drugs; Paliperidone ER, Oral risperidone; Dopamine; Fallypride; Plasma concentration; Therapeutic window, Healthy controls

Summary:

      The primary objective of this study is to compare the effect of two different antipsychotic
      compounds which are used in the treatment of schizophrenia (paliperidone ER and risperidone)
      at their target sites in two specific areas of the brain in patients with schizophrenia. A
      specialized X-ray known as Positron Emission Tomography (PET) Imaging is used to assess the
      areas of the brain targeted by both compounds.
    

Eligibility criteria:

        Inclusion Criteria:

          -  Patients with a diagnosis of schizophrenia according to Diagnostic and Statistical
             Manual of Mental Disorders (DSM-IV) criteria

          -  Patients with a specified severity of the disease (Clinical Global Impression Scale of
             Severity (CGI-S) range of > 2 < 5)

          -  Patients must be on antipsychotic medication with either paliperidone ER or oral
             risperidone in monotherapy for at least two weeks and must be at least five days on a
             stable dose of either paliperidone ER 6 mg or 9 mg or oral risperidone 4 mg or 6 mg
             once daily

          -  Female patients of childbearing potential must have a negative human chorionic
             gonadotropin urine pregnancy test (ß-HCG) at visit 1 or must be postmenopausal for at
             least 1 year, surgically sterile, abstinent, or, if sexually active, agree to practice
             an effective method of birth control before entry, throughout the study and at least
             one month after study end

          -  Healthy control volunteers must be off all standard prescription drug therapy, over
             the counter compounds (OTC) and recreational substances/drugs for at least one week
             prior to participation in the study

          -  Female volunteers of childbearing potential must have a negative ß -HCG pregnancy test
             at visit 1 or be postmenopausal for at least 1 year, surgically sterile, abstinent,
             or, if sexually active, agree to practice an effective method of birth control before
             entry, throughout the study and at least one month after the study end

          -  Patients and volunteers must be able to read, understand and sign the Institutional
             Review Board approved informed consent form

        Exclusion Criteria:

          -  Patients: Any depot neuroleptic medication (long acting injectables) in the last three
             months

          -  Any antipsychotic compound, antidepressant, antiepileptic ("mood stabilizers"),
             lithium, anticholinergic within 2 weeks prior to study

          -  Any psychopharmacologically active medication (except benzodiazepines, paracetamol and
             zopiclone as rescue medication) taken within the trial

          -  Physical and psychological conditions that interfere with the study procedures, or
             could influence the study results, or could endanger the patient during the study

          -  Alcohol and/or drug abuse four weeks prior to study start (patients with alcohol or
             drug abuse as defined by the DSM-IV criteria can participate if free of their of abuse
             for at least four weeks)

          -  Clinically relevant laboratory abnormality

          -  Pregnant or breast feeding patients