Trial · NCT00827918

A Study to Test the Safety and Efficacy of MK-8998 in Acutely Psychotic Participants With Schizophrenia (MK-8998-004)

NCT00827918, Phase 2, Completed, Merck Sharp & Dohme LLC; results first posted 2014-02-06

3 sourcestrials-2026-11-12-0.5.0

Cite this record

ConductScience Library. A Study to Test the Safety and Efficacy of MK-8998 in Acutely Psychotic Participants With Schizophrenia (MK-8998-004). Trials, record NCT00827918. Release trials-2026-11-12-0.5.0, 12 Nov 2026. https://conductscience.org/library/trials/NCT00827918

On this page

Trial

As registered on ClinicalTrials.gov, in the graph's capture of the registry.

Title: A Study to Test the Safety and Efficacy of MK-8998 in Acutely Psychotic Participants With Schizophrenia (MK-8998-004)
NCT number: NCT00827918
Status: Completed
Phases: Phase 2
Enrollment: 216 participants, actual
Lead sponsor: Merck Sharp & Dohme LLC
Conditions: Schizophrenia
Interventions: MK-8998, Comparator: Olanzapine, Comparator: Placebo
First posted: 2009-01-23
Last updated: 2015-10-21
Results first posted: 2014-02-06

Source ClinicalTrials.gov

Registered outcomes7

Each outcome the trial registered, primary first, in ClinicalTrials.gov's words.

List	Outcome	Time frame	Description
Primary	Mean Change From Baseline in the Positive and Negative Syndrome Scale (PANSS) at Week 4	Baseline and 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.
Primary	Number of Participants Who Experienced at Least One Adverse Event	Up to 6 Weeks	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.
Primary	Number of Participants Who Discontinued Study Drug Due to an Adverse Event	Up to 4 Weeks	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.
Secondary	Percentage of Participants With Response at Week 4	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.
Secondary	Mean Change From Baseline in Clinical Global Impression - Severity of Illness Scale (CGI-S) at Week 4	Baseline and 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.
Secondary	Mean Change From Baseline in PANSS Positive Subscale at Week 4	Baseline and 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.
Secondary	Mean Change From Baseline in PANSS Negative Subscale at Week 4	Baseline and 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.

Source ClinicalTrials.gov

Outcomes7

Each outcome the trial posted results for, in ClinicalTrials.gov's words.

Type	Outcome	Time frame	Population	Units	Measured as
PRIMARY	Mean Change From Baseline in the Positive and Negative Syndrome Scale (PANSS) at Week 4	Baseline and Week 4	Randomized participants with any PANSS measurements between Baseline and Week 4.	Units on a scale	LEAST_SQUARES_MEAN
PRIMARY	Number of Participants Who Experienced at Least One Adverse Event	Up to 6 Weeks	All participants included in the All Patients as Treated (APaT) population received at least one dose of study treatment and were evaluated for safety.	Participants	NUMBER
PRIMARY	Number of Participants Who Discontinued Study Drug Due to an Adverse Event	Up to 4 Weeks	All participants included in the All Patients as Treated (APaT) population received at least one dose of study treatment and were evaluated for safety.	Participants	NUMBER
SECONDARY	Percentage of Participants With Response at Week 4	Week 4	Randomized participants with a PANSS measurement at Week 4.	Percentage of participants	NUMBER
SECONDARY	Mean Change From Baseline in Clinical Global Impression - Severity of Illness Scale (CGI-S) at Week 4	Baseline and Week 4	Randomized participants with any CGI-S measurements between baseline and Week 4.	Units on a scale	LEAST_SQUARES_MEAN
SECONDARY	Mean Change From Baseline in PANSS Positive Subscale at Week 4	Baseline and Week 4	Randomized participants with any PANSS positive subscale measurements between baseline and Week 4.	Units on a scale	LEAST_SQUARES_MEAN
SECONDARY	Mean Change From Baseline in PANSS Negative Subscale at Week 4	Baseline and Week 4	Randomized participants with any PANSS negative subscale measurements between baseline and Week 4.	Units on a scale	LEAST_SQUARES_MEAN

Source ClinicalTrials.gov

Results by group21

Each measurement the trial posted, group by group, in the words and numbers it posted.

Outcome	Group	Value	Spread	Units
Mean Change From Baseline in the Positive and Negative Syndrome Scale (PANSS) at Week 4	MK-8998	-13.3	95% Confidence Interval -17.9 to -8.7	Units on a scale
Mean Change From Baseline in the Positive and Negative Syndrome Scale (PANSS) at Week 4	Olanzapine	-17.0	95% Confidence Interval -22.8 to -11.1	Units on a scale
Mean Change From Baseline in the Positive and Negative Syndrome Scale (PANSS) at Week 4	Placebo Comparator	-12.7	95% Confidence Interval -17.2 to -8.2	Units on a scale
Number of Participants Who Experienced at Least One Adverse Event	MK-8998	41		Participants
Number of Participants Who Experienced at Least One Adverse Event	Olanzapine	23		Participants
Number of Participants Who Experienced at Least One Adverse Event	Placebo Comparator	33		Participants
Number of Participants Who Discontinued Study Drug Due to an Adverse Event	MK-8998	9		Participants
Number of Participants Who Discontinued Study Drug Due to an Adverse Event	Olanzapine	1		Participants
Number of Participants Who Discontinued Study Drug Due to an Adverse Event	Placebo Comparator	1		Participants
Percentage of Participants With Response at Week 4	MK-8998	57.4		Percentage of participants

1 to 10 of 21Source ClinicalTrials.gov

See all 21 results by group

Participant flow9

How many started, completed or left each group, period by period.

Period	Milestone	Group	Participants
Overall Study	STARTED	MK-8998	86
Overall Study	STARTED	Olanzapine	47
Overall Study	STARTED	Placebo Comparator	83
Overall Study	COMPLETED	MK-8998	58
Overall Study	COMPLETED	Olanzapine	38
Overall Study	COMPLETED	Placebo Comparator	62
Overall Study	NOT COMPLETED	MK-8998	28
Overall Study	NOT COMPLETED	Olanzapine	9
Overall Study	NOT COMPLETED	Placebo Comparator	21

Source ClinicalTrials.gov

Adverse events15

Each adverse event the trial posted, group by group: the participants affected out of those at risk.

Type	Event	Organ system	Group	Affected	At risk	Events
other	Headache	Nervous system disorders	MK-8998	2	86	3
other	Headache	Nervous system disorders	Olanzapine	3	47	3
other	Headache	Nervous system disorders	Placebo Comparator	3	83	4
other	Somnolence	Nervous system disorders	MK-8998	2	86	2
other	Somnolence	Nervous system disorders	Olanzapine	3	47	8
other	Somnolence	Nervous system disorders	Placebo Comparator	1	83	1
other	Insomnia	Psychiatric disorders	MK-8998	13	86	14
other	Insomnia	Psychiatric disorders	Olanzapine	5	47	6
other	Insomnia	Psychiatric disorders	Placebo Comparator	7	83	8
other	Sinus tachycardia	Cardiac disorders	MK-8998	2	86	2

1 to 10 of 15Source ClinicalTrials.gov

See all 15 adverse events

Adverse event totals9

The totals the trial posted for each group.

Total	Group	Affected	At risk
Total, all-cause mortality	MK-8998
Total, all-cause mortality	Olanzapine
Total, all-cause mortality	Placebo Comparator
Total, other adverse events	MK-8998	19	86
Total, other adverse events	Olanzapine	14	47
Total, other adverse events	Placebo Comparator	11	83
Total, serious adverse events	MK-8998	0	86
Total, serious adverse events	Olanzapine	0	47
Total, serious adverse events	Placebo Comparator	1	83

Source ClinicalTrials.gov

Papers1

The papers the trial lists on ClinicalTrials.gov.

PMID	Listed as
23532746	DERIVED

Source PubMed

Grants0

The grants NIH RePORTER links to the trial, newest funded first: NIH's, and some of AHRQ's, CDC's, FDA's and VA's. Each shows its title, principal investigators, organization and funder in its newest year.

None in this release.

Trial comparisons0

Comparisons of the trial's two groups, calculated by ConductScience from the counts it posted.

None in this release.

Tests0

The ConductCognition tests this trial's registered outcomes name, as ScienceGraph matched them in trial-tests-2026-11-12-0.2.1.

None in this release.

Data dates

The day each source was copied for this release.

ClinicalTrials.gov: 2026-11-12; ClinicalTrials.gov
Results, from AACT: 2026-03-23; AACT
NIH grant links: 2026-11-13; NIH RePORTER

Sources 3

ClinicalTrials.gov's posted results, through CTTI's AACTFreely available. Acknowledgement requested
ClinicalTrials.govNo license stated
NIH RePORTER's clinical studies and project filesPublic domain

Each source's terms

ClinicalTrials.gov's posted results, through CTTI's AACTClinicalTrials.gov data via Aggregate Analysis of ClinicalTrials.gov (AACT), CTTI. CTTI makes its materials freely available and requests acknowledgement. https://aact.ctti-clinicaltrials.org/documentation/299
ClinicalTrials.govnone stated
NIH RePORTER's clinical studies and project filesPublic domain (NIH RePORTER)

ClinicalTrials.gov's data carry an international copyright outside the United States: https://clinicaltrials.gov/about-site/terms-conditions.

For software

Read this trial from software.

The record and each of its lists are JSON, twenty rows a page. No key.

GET https://conductscience.org/api/trials/v1/NCT00827918

GET https://conductscience.org/api/trials/v1/NCT00827918/results?page=2

API reference For AI assistants