Efficacy and Safety of Elpipodect (MK-8189) in Participants With an Acute Episode of Schizophrenia (MK-8189-008)

A Phase 2B Randomized, Double-Blind, Placebo- and Active-Controlled Trial of the Efficacy and Safety of MK-8189 in Participants Experiencing an Acute Episode of Schizophrenia

The purpose of this study was to evaluate the efficacy and safety of elpipodect at a range of doses (8 mg, 16 mg, and 24 mg once daily [QD]) in adult participants who have an acute episode of schizophrenia according to Diagnostic and Statistical Manual of Mental Disorders 5th Edition (DSM-5) criteria. The primary hypotheses were the following: (1) that elpipodect 24 mg is superior to placebo in reducing the Week 6 mean change from baseline in Positive and Negative Syndrome Scale (PANSS) total score, and (2) that elpipodect 16 mg is superior to placebo in reducing the Week 6 mean change from baseline in PANSS total score.

With Amendment 4, enrollment was changed to approximately 500 participants with removal of the elpipodect 8 mg treatment arm. Participants enrolled before Amendment 4 who were assigned to elpipodect 8 mg QD remained on that dose regimen per protocol.

Study Overview

• Status: Completed
• Conditions: Schizophrenia
• Intervention / Treatment: Drug: Placebo to risperidone; Drug: Risperidone; Drug: Placebo to MK-8189; Drug: Elpipodect

• Study Type: Interventional
• Enrollment (Actual): 499
• Phase: Phase 2

Contacts and Locations

Study Locations

• Bulgaria
  • Burgas, Bulgaria, 8001
    • Mental Health Center Prof. Dr. Ivan Temkov - Burgas EOOD ( Site 3002)
  • Kardzhali, Bulgaria, 6600
    • State Psychiatric Hospital - Kardzhali ( Site 3005)
  • Rousse, Bulgaria, 7000
    • Mental Health Center - Ruse, EOOD ( Site 3003)
  • Sofia, Bulgaria, 1000
    • Center for Mental Health Prof. Nikola Shipkovenski Ltd ( Site 3000)
  • Veliko Tarnovo, Bulgaria, 5000
    • Mental Health Center - Veliko Tarnovo ( Site 3006)
  • Sofia
    • Novi Iskar, Sofia, Bulgaria, 1282
      • State Psychiatric Hospital "Sv. Ivan Rilski", Novi Iskar ( Site 3001)
• Croatia
  • City of Zagreb
    • Zagreb, City of Zagreb, Croatia, 10090
      • Klinika za psihijatriju Vrapce ( Site 4000)
    • Zagreb, City of Zagreb, Croatia, 10090
      • Klinika za psihijatriju Vrapce ( Site 4001)
  • Primorje-Gorski Kotar County
    • Rijeka, Primorje-Gorski Kotar County, Croatia, 51000
      • Klinicki bolnicki centar Rijeka ( Site 4005)
  • Zagreb County
    • Zagreb, Zagreb County, Croatia, 10090
      • Klinika za psihijatriju Sveti Ivan ( Site 4003)
• Japan
  • Chiba, Japan, 260-8677
    • Chiba University Hospital ( Site 2024)
  • Fukuoka, Japan, 815-0074
    • Inokuchi Noma Hospital ( Site 2030)
  • Fukuoka, Japan, 819-0037
    • Kuramitsu Hospital ( Site 2014)
  • Kumamoto, Japan, 861-8002
    • Yuge Hospital ( Site 2018)
  • Tokyo, Japan, 121-8515
    • Seijin Hospital ( Site 2026)
  • Tokyo, Japan, 175-0091
    • Narimasu Kosei Hospital ( Site 2006)
  • Aichi-ken
    • Toyoake, Aichi-ken, Japan, 470-1168
      • Seishinkai Okehazama Hospital Fujita Kokoro Care Center ( Site 2011)
  • Chiba
    • Ichikawa, Chiba, Japan, 272-8516
      • Kohnodai Hospital, National Center for Global Health and Medicine ( Site 2005)
  • Fukuoka
    • Kitakyushu, Fukuoka, Japan, 808-0139
      • Wakato Hospital ( Site 2031)
    • Omuta, Fukuoka, Japan, 8360004
      • Shiranui Hospital ( Site 2043)
  • Gunma
    • Tomioka, Gunma, Japan, 3702455
      • Seimou Hospital ( Site 2004)
  • Kanagawa
    • Atsugi, Kanagawa, Japan, 243-0201
      • Soushu Hospital ( Site 2008)
    • Hadano, Kanagawa, Japan, 259-1304
      • Tanzawa Hospital ( Site 2037)
    • Yokohama, Kanagawa, Japan, 233-0006
      • Kanagawa Psychiatric Center ( Site 2035)
  • Nagano
    • Komoro, Nagano, Japan, 384-8540
      • Komoro Kogen Hospital ( Site 2046)
  • Okinawa
    • Kunigamigun, Okinawa, Japan, 904-1201
      • National Hospital Organization Ryukyu Hospital ( Site 2019)
    • Naha, Okinawa, Japan, 900-0005
      • Amekudai Hospital ( Site 2020)
  • Saga-ken
    • Kanzaki-gun, Saga-ken, Japan, 8420192
      • National Hospital Organization Hizen Psychiatric Medical Center ( Site 2017)
    • Karatsu, Saga-ken, Japan, 847-0031
      • Rainbow and Sea Hospital ( Site 2016)
  • Tokyo
    • Hachiōji, Tokyo, Japan, 192-0153
      • Ongata Hospital ( Site 2007)
    • Kita-ku, Tokyo, Japan, 114-0024
      • Nishigahara Hospital ( Site 2042)
    • Kodaira, Tokyo, Japan, 187-8551
      • National Center of Neurology and Psychiatry ( Site 2023)
• Latvia
  • Daugavpils, Latvia, 5417
    • Daugavpils Psihoneirologiska Slimnica ( Site 8005)
  • Liepāja, Latvia, 3401
    • Piejuras Slimnica Psihiatriska Klinika ( Site 8001)
• Poland
  • Greater Poland Voivodeship
    • Poznan, Greater Poland Voivodeship, Poland, 61-485
      • Centrum Medyczne HCP ( Site 0913)
  • Masovian Voivodeship
    • Pruszków, Masovian Voivodeship, Poland, 05-802
      • Klinika Psychiatryczna Wydzialu Nauki o Zdrowiu WUM ( Site 0900)
    • Warsaw, Masovian Voivodeship, Poland, 00-665
      • Samodzielny Wojewódzki Zespół Publicznych Zakładów Psychiatrycznej Opieki Zdrowotnej w Warszawie ( S
  • Pomeranian Voivodeship
    • Gdansk, Pomeranian Voivodeship, Poland, 80-211
      • Uniwersyteckie Centrum Kliniczne ( Site 0902)
  • Łódź Voivodeship
    • Lodz, Łódź Voivodeship, Poland, 91-229
      • Specjal. Psychiatryczny ZOZ w Lodzi, Szpital im. Babinskiego ( Site 0905)
• Romania
  • Bucharest
    • Bucharest, Bucharest, Romania, 041914
      • Prof. Dr. Alexandru Obregia Psychiatry Hospital ( Site 0815)
    • Bucharest, Bucharest, Romania, 041914
      • Prof. Dr. Alexandru Obregia Psychiatry Hospital ( Site 0816)
    • Bucharest, Bucharest, Romania, 041914
      • Prof. Dr. Alexandru Obregia Psychiatry Hospital ( Site 0817)
    • Bucharest, Bucharest, Romania, 041914
      • Prof. Dr. Alexandru Obregia Psychiatry Hospital ( Site 0818)
  • Iaşi
    • Iași, Iaşi, Romania, 700282
      • Institutul de Psihiatrie Socola ( Site 0810)
    • Iași, Iaşi, Romania, 700282
      • Institutul de Psihiatrie Socola ( Site 0814)
• Russia
  • Arkhangelskaya oblast
    • Arkhangelsk, Arkhangelskaya oblast, Russia, 163530
      • Arkhangelsk Regional Psychiatric Clinical Hospital ( Site 6020)
  • Leningradskaya Oblast'
    • Leningrad Region, Leningradskaya Oblast', Russia, 188820
      • SGHI Leningrad Region Psyconeurology Dispensary ( Site 6017)
  • Lipetsk Oblast
    • Lipetsk, Lipetsk Oblast, Russia, 399083
      • Lipetsk Regional Psychoneurology Hospital ( Site 6021)
  • Moscow
    • Moscow, Moscow, Russia, 107076
      • Moscow Scientific Research Institute for Psychiatry ( Site 6013)
    • Moscow, Moscow, Russia, 107076
      • Psychiatric Clinical Hospital 4 named after PB Gannushkin ( Site 6016)
    • Moscow, Moscow, Russia, 107076
      • Psychiatric Clinical Hospital 4 named after PB Gannushkin-Psychiatric department 4 ( Site 6023)
    • Moscow, Moscow, Russia, 127083
      • Central Moscow Regional Clinical Psychiatric Hospital ( Site 6018)
  • Sankt-Peterburg
    • Saint Petersburg, Sankt-Peterburg, Russia, 192019
      • Bekhterev Research Institute for Psychoneurology ( Site 6008)
    • Saint Petersburg, Sankt-Peterburg, Russia, 197341
      • SPb City Psychiatric Hospital #3 na II Skvortsov-Stepanov ( Site 6000)
    • Saint Petersburg, Sankt-Peterburg, Russia, 197341
      • SPb City Psychiatric Hospital #3 na II Skvortsov-Stepanov ( Site 6001)
    • Saint Petersburg, Sankt-Peterburg, Russia, 197341
      • SPb City Psychiatric Hospital #3 na II Skvortsov-Stepanov ( Site 6002)
  • Stavropol Kray
    • Stavropol, Stavropol Kray, Russia, 357034
      • Stavropol Region Psychiatric Hospital #2 ( Site 6005)
  • Tomsk Oblast
    • Tomsk, Tomsk Oblast, Russia, 634014
      • Federal State Scientific Institution Research Institute of Mental Health ( Site 6014)
  • Yaroslavl Oblast
    • Yaroslavl, Yaroslavl Oblast, Russia, 150003
      • Yaroslavl Regional Clinical Psychiatry Hospital ( Site 6022)
• Serbia
  • Beograd
    • Belgrade, Beograd, Serbia, 11000
      • Clinical Center of Serbia ( Site 5101)
    • Belgrade, Beograd, Serbia, 11000
      • Clinical Center of Serbia ( Site 5107)
    • Belgrade, Beograd, Serbia, 11000
      • Institut za mentalno zdravlje ( Site 5105)
    • Belgrade, Beograd, Serbia, 11000
      • University Clinical Hospital Center "Dr. Dragisa Misovic - Dedinje" ( Site 5104)
  • Sumadijski Okrug
    • Kragujevac, Sumadijski Okrug, Serbia, 34000
      • Clinical Center Kragujevac ( Site 5100)
    • Kragujevac, Sumadijski Okrug, Serbia, 34000
      • Clinical Center Kragujevac ( Site 5102)
    • Kragujevac, Sumadijski Okrug, Serbia, 34000
      • Clinical Center Kragujevac ( Site 5106)
  • Vojvodina
    • Kovin, Vojvodina, Serbia, 26220
      • Special Hospital for Psychiatric Diseases Kovin ( Site 5108)
    • Kovin, Vojvodina, Serbia, 26220
      • Special Hospital for Psychiatric Diseases Kovin ( Site 5109)
• South Korea
  • Seoul, South Korea, 03080
    • Seoul National University Hospital ( Site 0600)
  • Pusan-Kwangyokshi
    • Busan, Pusan-Kwangyokshi, South Korea, 47392
      • Inje University Busan Paik Hospital ( Site 0604)
  • Taegu-Kwangyokshi
    • Daegu, Taegu-Kwangyokshi, South Korea, 41944
      • Kyungpook National University Hospital ( Site 0601)
• Taiwan
  • Taichung, Taiwan, 404
    • China Medical University Hospital ( Site 9006)
  • Taipei, Taiwan, 100
    • National Taiwan University Hospital ( Site 9001)
  • Taipei, Taiwan, 110
    • Taipei City Hospital, Songde Branch ( Site 9004)
  • Taipei, Taiwan, 11217
    • Taipei Veterans General Hospital ( Site 9000)
  • Taoyuan District, Taiwan, 333
    • Chang Gung Memorial Hospital - Linkou Branch ( Site 9002)
• Ukraine
  • Cherkasy Oblast
    • Smila, Cherkasy Oblast, Ukraine, 20708
      • CNE Cherkasy reg. psychiatric hospital of Cherkasy regional council ( Site 7009)
  • Dnipropetrovsk Oblast
    • Dnipro, Dnipropetrovsk Oblast, Ukraine, 49005
      • Dnepropetrovsk Regional Clinical Hospital Mechnikov-Regional Centre of Psychosomatic Disorders base
  • Ivano-Frankivsk Oblast
    • Ivano-Frankivsk, Ivano-Frankivsk Oblast, Ukraine, 76014
      • CNE "Precarpathian Regional Clinical Center of Mental Health of Ivano-Frankivsk Regional Council"" (
  • Kharkivs’ka Oblast’
    • Kharkiv, Kharkivs’ka Oblast’, Ukraine, 61068
      • CNE of Kharkiv Reg. Council Reg. Clinical Psychiatric Hospital Nub 3 ( Site 7012)
    • Kharkiv, Kharkivs’ka Oblast’, Ukraine, 61068
      • Institute of Neurology,Psychiatry and Narcology AMS Ukraine ( Site 7011)
  • Kherson Oblast
    • Kherson, Kherson Oblast, Ukraine, 73488
      • CNE. Kherson Regional Psychiatric Hospital ( Site 7004)
  • Kyivska Oblast
    • Kyiv, Kyivska Oblast, Ukraine, 02192
      • Kyiv City Psychoneurological Hospital 2 ( Site 7008)
    • Kyiv, Kyivska Oblast, Ukraine, 04080
      • CNE Clinical Hospital PSYCHIATRY of executive body of Kyiv City Council -Kyiv City State Admin ( Sit
    • Kyiv, Kyivska Oblast, Ukraine, 08631
      • MNE of KRC-Regional psychiatric and narcological medical association ( Site 7005)
  • Vinnytsia Oblast
    • Vinnytsia, Vinnytsia Oblast, Ukraine, 21037
      • CNE "Vinnytsia Regional Clinical Psycho-neurological hospita-Mixed (men and women) department #2 ( S
• United States
  • Arkansas
    • Bentonville, Arkansas, United States, 72712-3873
      • Pillar Clinical Research ( Site 1047)
    • Little Rock, Arkansas, United States, 72211
      • Woodland International Research Group, LLC ( Site 1002)
    • Rogers, Arkansas, United States, 72758
      • Woodland Research Northwest, LLC ( Site 1036)
  • California
    • Bellflower, California, United States, 90706
      • CITRIALS ( Site 1010)
    • Culver City, California, United States, 90230
      • ProScience Research Group ( Site 1046)
    • Garden Grove, California, United States, 92845
      • Collaborative Neuroscience Research, LLC ( Site 1041)
    • Glendale, California, United States, 91206
      • Behavioral Research Specialists, LLC ( Site 1032)
    • Riverside, California, United States, 92506
      • CITRIALS ( Site 1016)
    • San Diego, California, United States, 92103
      • Artemis Institute for Clinical Research ( Site 1019)
    • San Diego, California, United States, 92123
      • California Neuropsychopharmacology Clinical Research Institute, LLC (CNRI-San Diego, LLC) ( Site 103
    • Sherman Oaks, California, United States, 91403
      • Schuster Medical Research Institute ( Site 1023)
  • Florida
    • Hollywood, Florida, United States, 33021
      • Behavioral Clinical Research ( Site 1058)
    • Hollywood, Florida, United States, 33024
      • Research Centers of America ( Hollywood )-Central Nervous System (CNS) ( Site 1065)
    • Miami, Florida, United States, 33122
      • Premier Clinical Research Institute ( Site 1049)
    • Miami Lakes, Florida, United States, 33016
      • Behavioral Clinical Research , Inc ( Site 1013)
    • Oakland Park, Florida, United States, 33334
      • Fort Lauderdale Behavioral Health Center ( Site 1028)
    • Stuart, Florida, United States, 34997
      • Health Synergy Clinical Research ( Site 1051)
  • Georgia
    • Atlanta, Georgia, United States, 30331
      • Atlanta Center for Medical Research ( Site 1022)
    • Decatur, Georgia, United States, 30030
      • CenExel iResearch, LLC ( Site 1039)
  • Illinois
    • Chicago, Illinois, United States, 60622
      • Ascension Saint Elizabeth ( Site 1000)
    • Chicago, Illinois, United States, 60640
      • Uptown Research Institute ( Site 1052)
    • Chicago, Illinois, United States, 60641
      • Pillar Clinical Research, LLC ( Site 1038)
  • Louisiana
    • Shreveport, Louisiana, United States, 71101
      • Benchmark Research ( Site 1054)
  • Maryland
    • Gaithersburg, Maryland, United States, 20877
      • CBH Health ( Site 1044)
  • Massachusetts
    • Boston, Massachusetts, United States, 02114
      • Massachusetts General Hospital ( Site 1035)
  • Missouri
    • St Louis, Missouri, United States, 63141
      • Arch Clinical Trials ( Site 1048)
  • Nevada
    • Las Vegas, Nevada, United States, 89102
      • Altea Research Institute ( Site 1012)
  • New Jersey
    • Marlton, New Jersey, United States, 08053
      • Hassman Research Institute Marlton Site ( Site 1040)
  • New York
    • Staten Island, New York, United States, 10314
      • Richmond Behavioral Associates ( Site 1064)
  • North Carolina
    • Charlotte, North Carolina, United States, 28211
      • New Hope Clinical Research ( Site 1050)
  • Ohio
    • Dayton, Ohio, United States, 45417
      • Midwest Clinical Research ( Site 1059)
    • Dayton, Ohio, United States, 45417
      • Midwest Clinical Research Center ( Site 1033)
    • North Canton, Ohio, United States, 44720
      • Neuro-Behavioral Clinical Research ( Site 1055)
  • Texas
    • Austin, Texas, United States, 78754
      • Community Clinical Research ( Site 1057)
    • Richardson, Texas, United States, 75080
      • Pillar Clinical Research, LLC ( Site 1004)

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 55 years (Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

The main inclusion criteria include, but are not limited to the following:

• Meet the diagnostic criteria for schizophrenia according to the DSM-5
• Have an illness duration for schizophrenia of at least 1 year
• Be confirmed to be experiencing an acute episode of schizophrenia as evidenced by ALL of the following: (a) onset of the current acute episode is ≤6 weeks before screening (b) current symptoms represent a marked and substantial worsening compared with the participant's usual symptomatic state prior to the current acute episode, and are associated with diminished functional ability (c) in need of increased psychiatric attention to treat worsening acute episode symptoms
• Have a CGI-S score of ≥4 (moderately ill) at screening and baseline
• Have an identified responsible person referred to as the "external contact person" who has agreed to provide information about the participant's location if needed during outpatient portion of the study. The site personnel must consider this identified responsible person a reliable contact person, and the contact person must have regular contact with the participant (defined at screening as direct contact no fewer than 3 times per week), and with the expectation that this frequency of contact would continue (either in person or via other contact method), throughout duration of the study, including the follow-up period)

Exclusion Criteria:

The main exclusion criteria include, but are not limited to the following:

• Has a primary current diagnosis other than schizophrenia or a comorbid diagnosis that is primarily responsible for the current symptoms and functional impairment
• Meets criteria for moderate to severe substance use disorder within past 6 months prior to screening (excluding those related to caffeine or nicotine)
• Has a known history of the following: (a) borderline personality disorder, anti-social personality disorder, or bipolar disorder (b) traumatic brain injury causing ongoing cognitive difficulties, Alzheimer's Disease, or another form of dementia, or any chronic organic disease of the central nervous system (c) intellectual disability of a severity that would impact ability to participate in the study
• Has a current diagnosis of a psychotic disorder other than schizophrenia or a behavioral disturbance thought to be due to substance abuse
• Is or was under involuntary commitment for the acute episode, because the participant is considered a danger to themselves or others
• Has a history of treatment resistance exhibited by any of the following: (a) no or minimal response to at least 2 periods of treatment lasting 6 weeks or longer, with antipsychotic agents at the maximally tolerated dose. Participants who have responded to antipsychotics only when paired with clozapine are considered treatment-resistant (b) history of electroconvulsive therapy (ECT) treatment for treatment-resistant schizophrenia within the past 6 months (c) past or current use of clozapine as single or adjunctive therapy for schizophrenia within the past 3 months
• Is currently participating in or has participated in another clinical study and received an experimental or investigational drug agent within 3 months prior to screening visit of this current study and has participated in no more than 2 studies in the past 2 years

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Triple

Number of Arms

5

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Risperidone 6 mg; Participants will be treated for a total of 12 weeks. Participants will receive risperidone 6 mg QD in the acute treatment period from Week 1-6 followed by risperidone 6 mg QD in the extension treatment period from Week 7-12.	Drug: Risperidone; Risperidone administered QD at a dose of 6 mg via oral capsule.; Drug: Placebo to MK-8189; MK-8189-matching placebo administered QD via oral tablet.
Experimental: Elpipodect 8 mg; Participants received elpipodect 8 mg QD from Weeks 1 to 12, with 2 weeks of follow-up	Drug: Placebo to risperidone; Risperidone-matching placebo administered QD via oral capsule.; Drug: Elpipodect; MK-8189 administered QD at a dose of 8 mg, 16 mg, or 24 mg via oral tablet.; Other Names: MK-8189
Experimental: Elpipodect 16 mg; Participants received elpipodect 16 mg QD from Weeks 1 to 12, with 2 weeks of follow-up.	Drug: Placebo to risperidone; Risperidone-matching placebo administered QD via oral capsule.; Drug: Elpipodect; MK-8189 administered QD at a dose of 8 mg, 16 mg, or 24 mg via oral tablet.; Other Names: MK-8189
Experimental: Elpipodect 24 mg; Participants received elpipodect 24 mg QD from Weeks 1 to 12, with 2 weeks of follow-up.	Drug: Placebo to risperidone; Risperidone-matching placebo administered QD via oral capsule.; Drug: Elpipodect; MK-8189 administered QD at a dose of 8 mg, 16 mg, or 24 mg via oral tablet.; Other Names: MK-8189
Experimental: Placebo and Elpipodect 24 mg; Participants received placebo QD from Weeks 1 to 6 and elpipodect 24 mg from Weeks 7 to 12, with 2 weeks of follow-up.	Drug: Placebo to risperidone; Risperidone-matching placebo administered QD via oral capsule.; Drug: Placebo to MK-8189; MK-8189-matching placebo administered QD via oral tablet.; Drug: Elpipodect; MK-8189 administered QD at a dose of 8 mg, 16 mg, or 24 mg via oral tablet.; Other Names: MK-8189

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change From Baseline in Positive and Negative Syndrome Scale (PANSS) Total Score at Week 6	The PANSS assesses the severity of schizophrenia symptoms through a 30-item clinician-rated inventory organized into a positive subscale (7 items), a negative subscale (7 items) and a general psychopathology subscale (16 items). For each item, symptoms are rated on a 7-point scale from 1 (absent) to 7 (extreme). The PANSS total score for each participant was calculated as the sum of the rating assigned to each of the 30 PANSS items, and ranges from 30 (lowest total score) to 210 (highest total score). Higher and lower change scores reflect symptom worsening and improvement, respectively. Risperidone and placebo were active and inactive controls, respectively.	Baseline and Week 6
Number of Participants Who Experience One or More Adverse Events (AEs)	An AE is any untoward medical occurrence in a clinical study participant, temporarily associated with the use of study intervention, whether or not considered related to the study intervention. Per protocol, events were assessed for the first 6 weeks of treatment.	Up to Week 6
Number of Participants Who Discontinued From Study Intervention Due to AE	An AE is any untoward medical occurrence in a clinical study participant, temporarily associated with the use of study intervention, whether or not considered related to the study intervention. Per protocol, events were assessed for the first 6 weeks of treatment.	Up to Week 6

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change From Baseline in PANSS Positive Subscale (PSS) Score at Week 6	The PANSS Positive Subscale (PSS) assesses the severity of schizophrenia symptoms. The PANSS PSS score was calculated as the sum of the rating assigned to each of the 7 PSS items and ranges from 7 (lowest total score) to 49 (highest total score). Higher and lower change scores reflect symptom worsening and improvement, respectively. Risperidone and placebo were active and inactive controls, respectively.	Baseline and Week 6
Change From Baseline in Clinical Global Impression-Severity of Illness (CGI-S) Score at Week 6	The CGI-S is a single item 7-point clinician rated scale for assessing the global severity of the participant's illness. CGI-S scores range from 1 (participant normal, not ill) to 7 (participant extremely ill); higher and lower change from baseline scores indicate symptom worsening and improvement, respectively. Risperidone and placebo were active and inactive controls, respectively.	Baseline and Week 6
Change From Baseline in Body Weight at Week 12	The change from baseline in body weigh was determined at Week 12. Negative and positive values represent body weight loss and gain from baseline, respectively. Weight was measured using a standardized scale. Risperidone and placebo were active and inactive controls, respectively.	Baseline and Week 12
Change From Baseline in Body Weight at Week 6	The change from baseline in body weigh was determined at Week 6. Negative and positive values represent body weight loss and gain from baseline, respectively. Weight was measured using a standardized scale. Risperidone and placebo were active and inactive controls, respectively.	Baseline and Week 6
Change From Baseline in Body Weight at Week 12: Model-based Analysis	The change from baseline in body weigh was determined at Week 12. Negative and positive values represent body weight loss and gain from baseline, respectively. Weight was measured using a standardized scale. Risperidone and placebo were active and inactive controls, respectively.	Baseline and Week 12
Change From Baseline in Body Weight at Week 6: Model-based Analysis	The change from baseline in body weigh was determined at Week 6. Negative and positive values represent body weight loss and gain from baseline, respectively. Weight was measured using a standardized scale. Risperidone and placebo were active and inactive controls, respectively.	Baseline and Week 6

Collaborators and Investigators

• Sponsor: Merck Sharp & Dohme LLC
• Investigators: Study Director: Medical Director, Merck Sharp & Dohme LLC

Publications and helpful links

Helpful Links

• Merck Clinical Trials Information
• Plain Language Summary

Study record dates

Study Major Dates

• Study Start (Actual): December 15, 2020
• Primary Completion (Actual): June 21, 2024
• Study Completion (Actual): June 21, 2024

Study Registration Dates

• First Submitted: November 5, 2020
• First Submitted That Met QC Criteria: November 5, 2020
• First Posted (Actual): November 10, 2020

Study Record Updates

• Last Update Posted (Actual): April 29, 2026
• Last Update Submitted That Met QC Criteria: April 8, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Schizophrenia Spectrum and Other Psychotic Disorders; Mental Disorders; Schizophrenia; Heterocyclic Compounds, 1-Ring; Heterocyclic Compounds; Pyrimidines; Pyrimidinones; Risperidone; MK-8189
• Other Study ID Numbers: 8189-008; MK-8189-008 (Other Identifier: Merck Protocol Number); jRCT2071200096 (Registry Identifier: jRCT); 2020-000094-24 (EudraCT Number)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: http://engagezone.msd.com/doc/ProcedureAccessClinicalTrialData.pdf

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No