NarcolepsyPhase 1NCT06179407
Study of MK-6552 in Participants With Narcolepsy Type 1 (MK-6552-004)
A Phase 1 study testing MK-6552 in people with Narcolepsy, run by Merck Sharp & Dohme LLC at 5 sites in United States.
Trial summary
The purpose of this study was to evaluate the safety, efficacy, pharmacokinetics (PK), and pharmacodynamics (PD) of MK-6552 in participants with Narcolepsy Type 1 (NT1). The effect of single MK-6552 doses were assessed initially under open-label conditions to evaluate the safety, tolerability, and PK of MK-6552. Read more about this study
- Who is it for?
- Ages 18 to 55 years
- Conditions the study is for
- Narcolepsy
- What is being tested?
- MK-6552
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 9 participants
- Where
- 5 sitesUnited States
- Study dates
- 24 Jan 2024to 23 Oct 2024
- Phase
- Phase 1
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 55 years
- All sexes
- No healthy volunteers
- Adult
Who may be able to join
- Has a diagnosis of NT1, including a valid polysomnography within the previous 5 years and a current diagnosis of NT1 for at least 6 months based on criteria established by the International Classification of Sleep Disorders- Third Edition, or Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) [American Psychiatric Association 2013]
- Is positive for HLA-DQB1*06:02 allele supporting a diagnosis of NT1
- Has a baseline history of unequivocal cataplexy prior to initiation of anti-cataplexy medications
- Reports a total sleep time of > 6 hours on at least 4 out of 7 nights each week within the 4 weeks prior to screening visit
Who cannot join
- Has history of or current hypertension
- Has underlying cardiovascular or cerebrovascular conditions in which an acute rise in blood pressure would pose a clinical concern, including but nor limited to aneurysms or arteriovenous malformations
- Has a history of renal or hepatic impairment
- Has a history of cardiac ischemia or cerebral ischemia including but not limited to history of stroke, transient ischemic attack, or transient global amnesia
- Based on clinical interview and responses on the Columbia-Suicide Severity Rating Scale, is at imminent risk of self-harm or of harm to others in the opinion of the investigator
- Mentally or legally incapacitated, has significant emotional problems at the time of prestudy (screening) visit or expected during the conduct of the study or has a history of clinically significant psychiatric disorder of the last 5 years
Show all 10Show fewer
- History of cancer (malignancy)
- Has a history of any of the following sleep disorders: obstructive sleep apnea (OSA) defined as an Apnea Hypopnea Index > 15 per hour per the American Academy of Sleep Medicine alternate criteria, primary insomnia (within the past 6 months), circadian rhythm sleep disorder, shift work sleep disorder (within the past 6 months), clinically significant parasomnia at the discretion of the investigator
- Has a history of seizure disorder, clinically significant head trauma, or past invasive intracranial surgery or clinically significant dementia
- Positive test(s) for Hepatitis B surface antigen, hepatitis C antibodies, or human immunodeficiency virus
Trial locations and contacts
5 sites in 1 country.
5 sites in 1 country
United States5 sites
NeuroTrials Research Inc ( Site 0006)
Atlanta, Georgia, 30328
FutureSearch Trials of Neurology ( Site 0004)
Austin, Texas, 78731
Teradan Clinical Trials, LLC ( Site 0005)
Brandon, Florida, 33511
Delta Waves, Inc. ( Site 0008)
Colorado Springs, Colorado, 80918
Bogan Sleep Consultants ( Site 0001)
Columbia, South Carolina, 29201
About this study
Official title: A Two-Part Study to Assess the Safety, Tolerability, Pharmacokinetics and Sleep Latency Effects of MK-6552 in Participants With Narcolepsy Type 1
The purpose of this study was to evaluate the safety, efficacy, pharmacokinetics (PK), and pharmacodynamics (PD) of MK-6552 in participants with Narcolepsy Type 1 (NT1). The effect of single MK-6552 doses were assessed initially under open-label conditions to evaluate the safety, tolerability, and PK of MK-6552. The effect of repeated MK-6552 doses (every 8 hours [q8h] for 7 days) were assessed under double-blind and placebo-controlled conditions.
Read the detailed description
The study was terminated by the Sponsor on 15OCT2024 out of an abundance of caution regarding elevations in liver function tests in 3 participants (all cases were asymptomatic and none met Hy's law for drug-induced liver injury or SAE criteria).
- Conditions
- Narcolepsy
- Being tested
- MK-6552, Placebo
- Medical subject headings
- Narcolepsy
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
MK-6552Drug
Oral capsule
PlaceboDrug
Oral capsule matched to MK-6552
| Study group | Role | What they receive |
|---|---|---|
| Panel A | Experimental | Participants will receive single oral doses of MK-6552 in ascending fashion approximately 6 hours apart for a single day, based on safety and tolerability of the previous dose. Then, participants will receive multiple days of MK-6552 dosing (7 consecutive days) at the highest safe and well tolerated MK-6552 dose determined on an individual basis from Part 1. Receives: Drug: MK-6552; Drug: Placebo |
| Panel B | Experimental | Panel B will assess the effects of repeated MK-6552 dosing across a range of doses compared with placebo. Receives: Drug: MK-6552; Drug: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Number of Participants Experiencing an Adverse Event (AE)
An AE is any untoward medical occurrence in a participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. Events are reported according to dose. The number of participants with ≥1 AE is reported.
Measured: Up to ~34 weeks
Number of Participants Discontinuing Study Intervention Due to AE
An AE is any untoward medical occurrence in a participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. Events are reported according to dose. The number of participants that discontinued study intervention due to AE(s) is reported.
Measured: Up to ~34 weeks
Sleep Onset Latency Measured by the Maintenance of Wakefulness Test (MWT) Following 7 Days of MK-6554 Treatment
The MWT is a daytime polysomnographic procedure that measures objectively the ability to remain awake during sleep-inducing circumstances. Sleep onset latency is defined as the first occurrence of sustained sleep (i.e. 3 consecutive 30 second epochs of N1 [stage 1] sleep or any single 30 second epoch of N2 [stage 2], N3 [stage 3 and 4 combined] or REM). The primary outcome measure of sleep onset latency measured by the MWT on Day 7 of daily repeated MK-6552 treatment is reported.
Measured: 1 hour after Dose 1 and Dose 2 on Day 7
Secondary outcomes (10)
Area Under the Plasma Concentration-Time Curve of MK-6552 From Time Zero to Infinity (AUC0-∞)
The AUC0-∞ of MK-6554 was determined for arms receiving 2 oral doses spaced 6 hours apart.
Measured: Day 1 Dose 1: Predose, 0.25, 0.5, 1, 2, 3, 4, and 6 hours postdose 1. Day 1 Dose 2: 0.25, 0.5, 1, 2, 3, 4, 6, 8, 18, 21 and 24 hours postdose
Area Under the Plasma Concentration-Time Curve of MK-6552 From Time Zero to 24 Hours Postdose (AUC0-24)
The AUC0-24 of MK-6554 was determined for arms receiving 2 oral doses spaced 6 hours apart.
Measured: Day 1 Dose 1: Predose, 0.25, 0.5, 1, 2, 3, 4, and 6 hours postdose 1. Day 1 Dose 2: 0.25, 0.5, 1, 2, 3, 4, 6, 8, and 18 hours postdose
Maximum Concentration (Cmax) of MK-6552
The Cmax of MK-6554 was determined for arms receiving 2 oral doses spaced 6 hours apart.
Measured: Day 1 Dose 1: Predose, 0.25, 0.5, 1, 2, 3, 4, and 6 hours postdose. Day 1 Dose 2: 0.25, 0.5, 1, 2, 3, 4, 6, 8, 18, 21 and 24 hours postdose
Time to Maximum Concentration (Tmax) of MK-6552
The Tmax of MK-6554 was determined for arms receiving 2 oral doses spaced 6 hours apart.
Measured: Day 1 Dose 1: Predose, 0.25, 0.5, 1, 2, 3, 4, and 6 hours postdose. Day 1 Dose 2: 0.25, 0.5, 1, 2, 3, 4, 6, 8, 18, 21 and 24 hours postdose
Concentration of MK-6522 at 2 Hours Postdose (C2h)
The C2h of MK-6554 was determined for arms receiving 2 oral doses spaced 6 hours apart.
Measured: Day 1 Dose 1: 2 hours postdose. Day 1 Dose 2: 2 hours postdose.
Concentration of MK-6522 at 6 Hours Postdose (C6h)
The C6h of MK-6554 was determined for arms receiving 2 oral doses spaced 6 hours apart.
Measured: Day 1 Dose 1: 6 hours postdose
Concentration of MK-6522 at 18 Hours Postdose (C18h)
The C18h of MK-6554 was determined for arms receiving 2 oral doses spaced 6 hours apart.
Measured: Day 1 Dose 2: 18 hours postdose
Apparent Oral Clearance (CL/F) of MK-6552
The CL/F of MK-6554 was determined for arms receiving 2 oral doses spaced 6 hours apart.
Measured: Day 1 Dose 1: Predose, 0.25, 0.5, 1, 2, 3, 4, and 6 hours postdose 1. Day 1 Dose 2: 0.25, 0.5, 1, 2, 3, 4, 6, 8, 18, 21 and 24 hours postdose
Apparent Volume of Distribution (Vz/F) of MK-6552
The Vz/F of MK-6554 was determined for arms receiving 2 oral doses spaced 6 hours apart.
Measured: Day 1 Dose 1: Predose, 0.25, 0.5, 1, 2, 3, 4, and 6 hours postdose 1. Day 1 Dose 2: 0.25, 0.5, 1, 2, 3, 4, 6, 8, 18, 21 and 24 hours postdose
Apparent Terminal Half-life (t½) of MK-6552
The apparent t½ of MK-6554 was determined for arms receiving 2 oral doses spaced 6 hours apart.
Measured: Day 1 Dose 1: Predose, 0.25, 0.5, 1, 2, 3, 4, and 6 hours postdose. Day 1 Dose 2: 0.25, 0.5, 1, 2, 3, 4, 6, 8, 18, 21 and 24 hours postdose
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted21 Dec 2023
- Study start24 Jan 2024
- Primary completion23 Oct 2024
- Study completion23 Oct 2024
Why it stopped: Terminated for business reasons
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Other trials for NarcolepsyStudies of the same condition, open and under way.
- More trials run by Merck Sharp & Dohme LLCThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 1
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Sequential
- Masking
- Single blind
- Who is masked
- Participant
- Enrolment
- 9 participants (actual)
Sponsor and investigators
- Lead sponsor
- Merck Sharp & Dohme LLC
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
- Investigators
- Medical Director, Study director, Merck Sharp & Dohme LLC
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06179407
- Sponsor's protocol ID
- 6552-004
- Other IDs
- MK-6554-004
- Status last verified
- Mar 2026
- First submitted
- 12 Dec 2023
- Last updated
- 14 Apr 2026
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- Yes: https://trialstransparency.msdclinicaltrials.com/pdf/ProcedureAccessClinicalTrialData.pdf
Study at a glance
From the registry record, last updated by the sponsor on 14 Apr 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Two-Part Study to Assess the Safety, Tolerability, Pharmacokinetics and Sleep Latency Effects of MK-6552 in Participants With Narcolepsy Type 1
- ClinicalTrials.gov ID
- NCT06179407
- Acronym / sponsor ID
- 6552-004
- Conditions
- Narcolepsy
- Phase
- Phase 1
- Study type
- Interventional
- Recruitment status
- TerminatedReason stopped: Terminated for business reasons
- Enrolment
- 9 participants (actual)
- Lead sponsor
- Merck Sharp & Dohme LLCIndustry (pharma, biotech, devices)
- Study start
- 24 Jan 2024 (actual)
- Primary completion
- 23 Oct 2024 (actual)
- Study completion
- 23 Oct 2024 (actual)
- First posted
- 21 Dec 2023 (actual)
- Results
- Posted 14 Apr 2026
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The purpose of this study was to evaluate the safety, efficacy, pharmacokinetics (PK), and pharmacodynamics (PD) of MK-6552 in participants with Narcolepsy Type 1 (NT1). The effect of single MK-6552 doses were assessed initially under open-label conditions to evaluate the safety, tolerability, and PK of MK-6552. The effect of repeated MK-6552 doses (every 8 hours [q8h] for 7 days) were assessed under double-blind and placebo-controlled conditions.
Detailed description
The study was terminated by the Sponsor on 15OCT2024 out of an abundance of caution regarding elevations in liver function tests in 3 participants (all cases were asymptomatic and none met Hy's law for drug-induced liver injury or SAE criteria).
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Sequential
- Masking
- Single blind (participant)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Panel A | Experimental | Drug: MK-6552, Drug: PlaceboParticipants will receive single oral doses of MK-6552 in ascending fashion approximately 6 hours apart for a single day, based on safety and tolerability of the previous dose. Then, participants will receive multiple days of MK-6552 dosing (7 consecutive days) at the highest safe and well tolerated MK-6552 dose determined on an individual basis from Part 1. |
| Panel B | Experimental | Drug: MK-6552, Drug: PlaceboPanel B will assess the effects of repeated MK-6552 dosing across a range of doses compared with placebo. |
Who may qualify
- Ages
- 18 to 55 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult
Key inclusion criteria (4 listed)
- Has a diagnosis of NT1, including a valid polysomnography within the previous 5 years and a current diagnosis of NT1 for at least 6 months based on criteria established by the International Classification of Sleep Disorders- Third Edition, or Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) [American Psychiatric Association 2013]
- Is positive for HLA-DQB1*06:02 allele supporting a diagnosis of NT1
- Has a baseline history of unequivocal cataplexy prior to initiation of anti-cataplexy medications
- Reports a total sleep time of > 6 hours on at least 4 out of 7 nights each week within the 4 weeks prior to screening visit
Key exclusion criteria (10 listed)
- Has history of or current hypertension
- Has underlying cardiovascular or cerebrovascular conditions in which an acute rise in blood pressure would pose a clinical concern, including but nor limited to aneurysms or arteriovenous malformations
- Has a history of renal or hepatic impairment
- Has a history of cardiac ischemia or cerebral ischemia including but not limited to history of stroke, transient ischemic attack, or transient global amnesia
- Based on clinical interview and responses on the Columbia-Suicide Severity Rating Scale, is at imminent risk of self-harm or of harm to others in the opinion of the investigator
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| MK-6552Oral capsule | Drug | Panel A, Panel B |
| PlaceboOral capsule matched to MK-6552 | Drug | Panel A, Panel B |
Primary outcome
Number of Participants Experiencing an Adverse Event (AE)
Time frame: Up to ~34 weeks
An AE is any untoward medical occurrence in a participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. Events are reported according to dose. The number of participants with ≥1 AE is reported.
Number of Participants Discontinuing Study Intervention Due to AE
Time frame: Up to ~34 weeks
An AE is any untoward medical occurrence in a participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. Events are reported according to dose. The number of participants that discontinued study intervention due to AE(s) is reported.
Sleep Onset Latency Measured by the Maintenance of Wakefulness Test (MWT) Following 7 Days of MK-6554 Treatment
Time frame: 1 hour after Dose 1 and Dose 2 on Day 7
The MWT is a daytime polysomnographic procedure that measures objectively the ability to remain awake during sleep-inducing circumstances. Sleep onset latency is defined as the first occurrence of sustained sleep (i.e. 3 consecutive 30 second epochs of N1 [stage 1] sleep or any single 30 second epoch of N2 [stage 2], N3 [stage 3 and 4 combined] or REM). The primary outcome measure of sleep onset latency measured by the MWT on Day 7 of daily repeated MK-6552 treatment is reported.
10 secondary outcomes
Area Under the Plasma Concentration-Time Curve of MK-6552 From Time Zero to Infinity (AUC0-∞)
Time frame: Day 1 Dose 1: Predose, 0.25, 0.5, 1, 2, 3, 4, and 6 hours postdose 1. Day 1 Dose 2: 0.25, 0.5, 1, 2, 3, 4, 6, 8, 18, 21 and 24 hours postdose
Area Under the Plasma Concentration-Time Curve of MK-6552 From Time Zero to 24 Hours Postdose (AUC0-24)
Time frame: Day 1 Dose 1: Predose, 0.25, 0.5, 1, 2, 3, 4, and 6 hours postdose 1. Day 1 Dose 2: 0.25, 0.5, 1, 2, 3, 4, 6, 8, and 18 hours postdose
Maximum Concentration (Cmax) of MK-6552
Time frame: Day 1 Dose 1: Predose, 0.25, 0.5, 1, 2, 3, 4, and 6 hours postdose. Day 1 Dose 2: 0.25, 0.5, 1, 2, 3, 4, 6, 8, 18, 21 and 24 hours postdose
Time to Maximum Concentration (Tmax) of MK-6552
Time frame: Day 1 Dose 1: Predose, 0.25, 0.5, 1, 2, 3, 4, and 6 hours postdose. Day 1 Dose 2: 0.25, 0.5, 1, 2, 3, 4, 6, 8, 18, 21 and 24 hours postdose
Concentration of MK-6522 at 2 Hours Postdose (C2h)
Time frame: Day 1 Dose 1: 2 hours postdose. Day 1 Dose 2: 2 hours postdose.
Concentration of MK-6522 at 6 Hours Postdose (C6h)
Time frame: Day 1 Dose 1: 6 hours postdose
Concentration of MK-6522 at 18 Hours Postdose (C18h)
Time frame: Day 1 Dose 2: 18 hours postdose
Apparent Oral Clearance (CL/F) of MK-6552
Time frame: Day 1 Dose 1: Predose, 0.25, 0.5, 1, 2, 3, 4, and 6 hours postdose 1. Day 1 Dose 2: 0.25, 0.5, 1, 2, 3, 4, 6, 8, 18, 21 and 24 hours postdose
Apparent Volume of Distribution (Vz/F) of MK-6552
Time frame: Day 1 Dose 1: Predose, 0.25, 0.5, 1, 2, 3, 4, and 6 hours postdose 1. Day 1 Dose 2: 0.25, 0.5, 1, 2, 3, 4, 6, 8, 18, 21 and 24 hours postdose
Apparent Terminal Half-life (t½) of MK-6552
Time frame: Day 1 Dose 1: Predose, 0.25, 0.5, 1, 2, 3, 4, and 6 hours postdose. Day 1 Dose 2: 0.25, 0.5, 1, 2, 3, 4, 6, 8, 18, 21 and 24 hours postdose
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 14 Apr 2026.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Merck Clinical Trials InformationLink provided by the sponsor.
- Individual participant dataSharing planned: Yes. https://trialstransparency.msdclinicaltrials.com/pdf/ProcedureAccessClinicalTrialData.pdf
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Medical Director study director
Merck Sharp & Dohme LLC
5 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 1 study testing MK-6552 in people with Narcolepsy, run by Merck Sharp & Dohme LLC at 5 sites in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 10 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: stopped early, as of the sponsor's last update on 14 Apr 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 5 sites in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
Yes. Results are posted in the registry (first posted 14 Apr 2026). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Number of Participants Experiencing an Adverse Event (AE) (time frame: Up to ~34 weeks). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 14 Apr 2026.