Adjuvant Treatment With a Glycine Uptake Inhibitor in Participants With Negative Symptoms of Schizophrenia (P05695) (MK-8435-001) (GIANT)
Schizophrenia
About this trial
This is an interventional treatment trial for Schizophrenia focused on measuring Negative symptoms, Glycine Uptake inhibitor, Add-on treatment, Second Generation Antipsychotic
Eligibility Criteria
Inclusion Criteria:
- Is diagnosed with non-first episode schizophrenia meeting Diagnostic and Statistical Manual (Version IV) criteria
- Is receiving stable treatment with one of the following SGA: aripiprazole, olanzapine, quetiapine, risperidone, or ziprasidone
- Is in the non-acute phase of illness and clinically stable for 3 months prior to study start as demonstrated by: treatment with current SGA or at least 12 weeks prior to study start; no increase in the level of psychiatric care due to worsening symptoms for at least 12 weeks prior to study start; and no dose change of SGA or change in medication to treat the symptoms of schizophrenia for 4 weeks prior to study start
- Has a score ≥4 on 3 or more of the following Positive and Negative Symptoms Scale (PANSS) negative subscale items at study start: blunted affect, emotional withdrawal, poor rapport, passive social withdrawal, lack of spontaneity, motor retardation, and active social avoidance
- Has an overall PANSS negative subscale score > 20
Exclusion Criteria:
- Has an overall PANSS positive subscale score ≥20
- Has a score ≥5 on 2 or more of the following PANSS positive subscale items at study start: delusions, hallucinatory behavior, excitement, grandiosity, or suspiciousness/persecution
- Has a score ≥9 on the modified InterSePT Scale for Suicidal Thinking
- Has a score ≥9 on the Calgary Depression Scale for Schizophrenia
- Has a score ≥3 on the clinical global impression of Parkinsonism of the abbreviated Extrapyramidal Symptom Rating Scale
- Has untreated or uncompensated clinically significant renal, endocrine, hepatic, respiratory, cardiovascular, hematological, immunological or cerebrovascular disease, malignancy, or other chronic and/or degenerative process
- Has a history of seizure disorder beyond childhood or is taking any anticonvulsants to prevent seizures
- Has a diagnosis of mental retardation or organic brain syndrome
- Has a clinically relevant visual disturbance, such as cataract, color blindness, macular degeneration, glaucoma, or retinal disease
- Has a concurrent diagnosis of substance dependence other than nicotine or caffeine dependence in the past 6 months prior to study start
- Has a positive result on the urine alcohol/drug screen for alcohol or illicit drugs
- Is pregnant or breastfeeding
- Is being treated with high doses of benzodiazepines (>4 mg per day lorazepam or equivalent)
- Has an imminent risk of self-harm or harm to others
- Has been treated with clozapine in the past 6 months prior to study start
- Has been treated with lithium, valproate, lamotrigine, pregabalin, gabapentin, or carbamazepine in the past 12 weeks prior to study start
- Has started treatment or has had a dose change of an (additional) antipsychotic, antidepressant,hypnotic or anxiolytic in the past 4 weeks prior to study start
- Has had no demonstrated benefit of antipsychotic treatment within the previous five years
Sites / Locations
Arms of the Study
Arm 1
Arm 2
Arm 3
Experimental
Experimental
Placebo Comparator
MK-8435 (Org 25935) 8-16 mg per day
MK-8435 (Org 25935) 24-32 mg per day
Placebo
Participants will be maintained on a stable dose of Second Generation Antipsychotic (SGA) and receive 4-8 mg MK-8435 (Org 25935) BID, in the morning and the evening, as add-on treatment for up to 87 days. The dose of MK-8435 (Org 25935) can be titrated upward or downward within the specified dose range, as needed, up to Day 42 of the study. The dose must remain stable after Day 42 for the remainder of the study.
Participants will be maintained on a stable dose of SGA and receive 12-16 mg MK-8435 (Org 25935) BID, in the morning and the evening, as add-on treatment for up to 87 days. The dose of MK-8435 (Org 25935) can be titrated upward or downward within the specified dose range, as needed, up to Day 42 of the study. The dose must remain stable after Day 42 for the remainder of the study.
Participants will be maintained on a stable dose of SGA and receive matching placebo for MK-8435 (Org 25935) BID, in the morning and the evening, as add-on treatment for up to 87 days.