A study to evaluate the safety and efficacy of treatment with MK-8998 as compared to placebo and olanzapine for acutely psychotic patients with schizophrenia. The primary hypothesis is that in participants undergoing an acute psychotic episode of schizophrenia, MK-8998 6 to 8 mg twice daily is superior to placebo in the treatment of symptoms of schizophrenia as measured by the mean change from baseline in the Positive and Negative Syndrome Scale (PANSS) total score at Week 4.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
TRIPLE
Enrollment
216
MK-8998 6 mg capsules twice daily with food on Days 1 through 7. On Day 8, dosage will be increased to 8 mg capsules twice daily. Treatment period is 4 weeks. There will be a period of time when all participants will receive placebo.
Olanzapine 5 mg tablets twice daily with food on Days 1 through 7. On Day 8, dosage will be increased to 5 mg tablets in the morning and 10 mg tablets in the evening. Treatment period is 4 weeks. There will be a period of time when all participants will receive placebo.
Placebo tablets matching olanzapine tablets and MK-8998 capsules
Mean Change From Baseline in the Positive and Negative Syndrome Scale (PANSS) at Week 4
PANSS is a medical scale used for measuring symptom severity of participants with schizophrenia. PANSS measure is composed of 3 scales: Positive scale, Negative scale, and General Psychopathology scale. Positive scale assesses hallucinations, delusions and related symptoms; Negative scale assesses emotional withdrawal, lack of motivation, and similar symptoms; and General Psychopathology scale addresses other symptoms such as anxiety, somatic concern and disorientation. The PANSS has 30 items in its 3 scales and an anchored Likert scale from 1 to 7 is used to score each item. Values of 2 and above indicate the presence of progressively more severe symptoms. The Positive scale has 7 items with a score from 7 to 49, the Negative scale has 7 items with a score from 7 to 49, and the General Psychopathology scale has 16 items with a score from 16 to 112. A total score is the sum of the 3 scores for the 3 scales.
Time frame: Baseline and Week 4
Number of Participants Who Experienced at Least One Adverse Event
An adverse event (AE) is any unfavorable and unintended change in the structure, function or chemistry of the body temporally associated with study drug administration whether or not considered related to the use of the study drug.
Time frame: Up to 6 Weeks
Number of Participants Who Discontinued Study Drug Due to an Adverse Event
An AE is any unfavorable and unintended change in the structure, function or chemistry of the body temporally associated with study drug administration whether or not considered related to the use of the study drug.
Time frame: Up to 4 Weeks
Percentage of Participants With Response at Week 4
Responders were defined as participants who demonstrated ≥ 20% improvement from baseline on the PANSS total score. PANSS measure is composed of 3 scales: Positive scale, Negative scale, and General Psychopathology scale. Positive scale assesses hallucinations, delusions and related symptoms; Negative scale assesses emotional withdrawal, lack of motivation, and similar symptoms; and General Psychopathology scale addresses other symptoms such as anxiety, somatic concern and disorientation. The PANSS has 30 items in its 3 scales and an anchored Likert scale from 1 to 7 is used to score each item. Values of 2 and above indicate the presence of progressively more severe symptoms. The Positive scale has 7 items with a score from 7 to 49, the Negative scale has 7 items with a score from 7 to 49, and the General Psychopathology scale has 16 items with a score from 16 to 112. A total score is the sum of the 3 scores for the 3 scales.
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Time frame: Week 4
Mean Change From Baseline in Clinical Global Impression - Severity of Illness Scale (CGI-S) at Week 4
CGI-S is a commonly used measure of symptom severity in treatment studies of participants with mental disorders. CGI-S is a 7-point scale that requires the clinician to rate the severity of the participant's illness at the time of assessment, relative to the clinician's past experience with participants who have the same diagnosis. Considering total clinical experience, a participant is assessed on severity of mental illness at the time of rating 1 = normal, not at all ill; 2 = borderline mentally ill; 3 = mildly ill; 4 = moderately ill; 5 = markedly ill; 6 = severely ill; or 7 = extremely ill.
Time frame: Baseline and Week 4
Mean Change From Baseline in PANSS Positive Subscale at Week 4
PANSS Positive scale assesses hallucinations, delusions and related symptoms. The Positive scale has 7 items with an anchored Likert scale from 1 to 7 to score each item. Values of 2 and above indicate the presence of progressively more severe symptoms. A total score ranges from 7 to 49.
Time frame: Baseline and Week 4
Mean Change From Baseline in PANSS Negative Subscale at Week 4
PANSS Negative scale assesses emotional withdrawal, lack of motivation, and similar symptoms. The Negative scale has 7 items with an anchored Likert scale from 1 to 7 to score each item. Values of 2 and above indicate the presence of progressively more severe symptoms. A total score ranges from 7 to 49.
Time frame: Baseline and Week 4