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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Date data sharing statement initially provided
Date results information initially provided
Type of registration
Prospectively registered

Titles & IDs
Public title
The physiological effects of zolpidem in people with obstructive sleep apnoea
Scientific title
The effects of zolpidem on OSA severity
Secondary ID [1] 295657 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Obstructive sleep apnoea 308996 0
Condition category
Condition code
Respiratory 307896 307896 0 0
Sleep apnoea

Study type
Description of intervention(s) / exposure
Standard dose of zolpidem (10mg, oral tablet), each participant to receive zolpidem once, immediately before bed. Zolpidem to be taken orally in front of the investigator for these single-night, acute in-laboratory studies. 1 week washout between visits.

Intervention code [1] 301976 0
Treatment: Drugs
Comparator / control treatment
Placebo (sugar pill, oral tablet), in front of the investigator (participants will act as their own controls in a cross-over design)
Control group

Primary outcome [1] 306869 0
Sleep apnoea severity using the apnoea/hypopnoea index from the overnight polysomnogram
Timepoint [1] 306869 0
Single acute overnight sleep studies (zolpidem vs placebo)
Secondary outcome [1] 349986 0
Pharyngeal muscle activity during sleep using intramuscular electromyography (EMG).

Timepoint [1] 349986 0
Single acute overnight sleep studies on zolpidem vs. placebo
Secondary outcome [2] 349987 0
Respiratory arousal threshold (negative pharyngeal pressure immediately prior to arousal from sleep, using an epiglottic pressure catheter inserted via the nostril)

Timepoint [2] 349987 0
Single acute overnight sleep studies (zolpidem vs. placebo
Secondary outcome [3] 349988 0
Standard polysomnography (PSG) variable (nadir SaO2)
Timepoint [3] 349988 0
Single acute overnight sleep studies (zolpidem vs. placebo)
Secondary outcome [4] 350122 0
Standard PSG variable (sleep efficiency)
Timepoint [4] 350122 0
Single acute overnight sleep studies (zolpidem vs. placebo)
Secondary outcome [5] 350123 0
Standard PSG variable (sleep duration)
Timepoint [5] 350123 0
Single acute overnight sleep studies (zolpidem vs. placebo)
Secondary outcome [6] 350124 0
Standard PSG variable (Arousal index)
Timepoint [6] 350124 0
Single acute overnight sleep studies (zolpidem vs. placebo)
Secondary outcome [7] 350125 0
Daytime sleepiness (karolinska sleepiness scale )
Timepoint [7] 350125 0
Single acute overnight sleep studies (zolpidem vs. placebo)
Secondary outcome [8] 350126 0
Daytime sleepiness (next day driving simulator )
Timepoint [8] 350126 0
Single acute overnight sleep studies (zolpidem vs. placebo)

Key inclusion criteria
Otherwise healthy, men and women with obstructive sleep apnoea

Patients who have a low-moderate respiratory arousal threshold (between zero and -25cmH2O epiglottic pressure just prior to arousal) as estimated from their baseline sleep study.
Minimum age
18 Years
Maximum age
64 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
Patients with confirmed overnight blood oxygen saturation nadir (SaO2) less than 70% from baseline sleep study
Patients who are estimated to have a high arousal threshold (less than -25cmH2O epiglottic pressure prior to arousal)

Women lactating, pregnant or of childbearing potential who are not willing to avoid becoming pregnant during the study.
-Patients with any other medical condition which may interfere in the evaluation of the study.
-Patients with a previous history of addiction to alcohol or drugs.
-Patients taking medications known to affect sleep or muscle activity.

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
sealed opaque envelopes
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Randomisation table created by computer software (i.e. computerised sequence generation)
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s
The people administering the treatment/s
The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Other design features
Phase 2
Type of endpoint(s)
Statistical methods / analysis
A sample size of n=24 will allow us to detect a 7 event/h difference in the AHI with 90% power (SD=10) with a two-tailed paired t-test (alpha=0.05).

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)
Recruitment hospital [1] 11502 0
Prince of Wales Hospital - Randwick
Recruitment postcode(s) [1] 23528 0
2031 - Randwick

Funding & Sponsors
Funding source category [1] 300236 0
Government body
Name [1] 300236 0
National Health and Medical Research Council (NHMRC) CRE and Fellowship funding
Address [1] 300236 0
National Health and Medical Research Council
GPO Box 1421
Canberra ACT 2601

Country [1] 300236 0
Primary sponsor type
Neuroscience Research Australia (NeuRA)
Neuroscience Research Australia (NeuRA)
139 Barker Street,
Randwick, NSW, 2031

Secondary sponsor category [1] 299676 0
Name [1] 299676 0
Address [1] 299676 0
Country [1] 299676 0

Ethics approval
Ethics application status
Ethics committee name [1] 301059 0
South Eastern Sydney Local Health District Human Research Ethics Committee
Ethics committee address [1] 301059 0
Human Research Ethics Committee
Room G71 East wing
Edmund Blacket Building
Prince of Wales Hospital
NSW 2031
Ethics committee country [1] 301059 0
Date submitted for ethics approval [1] 301059 0
Approval date [1] 301059 0
Ethics approval number [1] 301059 0
16/355 (HREC/16/POWH/710)

Brief summary
The purpose of this physiology study is to determine the effects of zolpidem (10mg) on obstructive sleep apnoea severity, upper airway muscle activity, the respiratory arousal threshold and breathing parameters during sleep.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 85742 0
Prof Danny Eckert
Address 85742 0
Neuroscience Research Australia (NeuRA)
139 Barker Street
NSW 2031
Country 85742 0
Phone 85742 0
+61 2 9399 1814
Fax 85742 0
Email 85742 0
Contact person for public queries
Name 85743 0
Dr Jayne Carberry
Address 85743 0
Neuroscience Research Australia (NeuRA)
139 Barker Street
NSW 2031
Country 85743 0
Phone 85743 0
+61 2 9399 1834
Fax 85743 0
Email 85743 0
Contact person for scientific queries
Name 85744 0
Dr Jayne Carberry
Address 85744 0
Neuroscience Research Australia (NeuRA)
139 Barker Street
NSW 2031
Country 85744 0
Phone 85744 0
+61 2 9399 1834
Fax 85744 0
Email 85744 0

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
What data in particular will be shared?
Individual sleep and physiological data will only be made available if participant identity can be assured to remain anonymous in accordance with ethical approval at the commencement of this study.
When will data be available (start and end dates)?
After publication (No end date determined).
Available to whom?
Anyone who has access to the publication.
Available for what types of analyses?
Any purpose.
How or where can data be obtained?
Individual data will be provided within the publication.
What supporting documents are/will be available?
Ethical approval
How or where can supporting documents be obtained?
Type [1] 4135 0
Ethical approval
Citation [1] 4135 0
Link [1] 4135 0
Email [1] 4135 0
Other [1] 4135 0
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary