Sleep-Disordered BreathingPhase 2MORPHONCT06043830
Managing Opioid Related Sleep Apnea With Acetazolamide
A Phase 2 study testing Acetazolamide in people with Sleep-Disordered Breathing and Obstructive Sleep Apnea, run by University of California, San Diego at 1 site in United States.
Trial summary
Patients with chronic pain who use opioids appear to be at increased risk for breathing issues during sleep, termed sleep disordered breathing (SDB). Treatment of SDB often consists of use of a device during sleep that provides continuous positive airway pressure (CPAP) via a mask interface. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Sleep-Disordered Breathing, Obstructive Sleep Apnea, Central Sleep Apnea
- What is being tested?
- Acetazolamide
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 39 participants
- Where
- 1 siteUnited States
- Study dates
- 18 Oct 2023to 23 Dec 2025
- Phase
- Phase 2
- Are there results?
- None posted in the registry
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 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Age 18+
- Chronic pain
- Chronic opioid use (daily use for >3 months duration) with >/= 20 oral Morphine Equivalent Dose (MEqD) per day
- Apnea-hypopnea index >/= 10 events/hr (hypopnea definition: ≥ 3% desaturation or arousal criteria per American Academy of Sleep Medicine 2012 scoring rules)
Who cannot join
- Use of opioids outside medical supervision (e.g. recreational use)
- Unable or unwilling to withhold any ongoing SDB treatment (e.g. CPAP) for the duration of the study
- Urgent need to initiate effective SDB therapy
- Chronic lung disease (other than well-controlled asthma)
- Active cardiac disease including heart failure, chest pain, or heart rhythm problems
- Neurological or developmental problems affecting breathing
Show all 21Show fewer
- Major sleep disorders other than sleep apnea
- Chronic kidney disease
- Cirrhosis of the liver
- Active cancer treatment or limited life expectancy
- Psychiatric disease other than controlled mood disorders
- Use of diuretics, potassium supplementation, or medications that may affect potassium
- Allergy to study drug or related compounds including sulfa drugs
- Know electrolyte disturbances
- Hospitalized in the last 90 days or anticipated hospitalization within 3 months
- Alcohol use >2 standard drinks per day
- Presence of tracheostomy or artificial airway
- Prisoners
- Pregnancy or anticipating pregnancy in next 2 months, or nursing
- Unable or unwilling to provide informed consent
- Unable to follow study protocol
Trial locations and contacts
1 site in 1 country.
United States1 site
University of California San Diego
San Diego, California, 92037
About this study
Patients with chronic pain who use opioids appear to be at increased risk for breathing issues during sleep, termed sleep disordered breathing (SDB). Treatment of SDB often consists of use of a device during sleep that provides continuous positive airway pressure (CPAP) via a mask interface. However, this device is not effective or tolerated in all individuals. The goal of this study is to examine whether a medication called acetazolamide can improve SDB, as an alternative to CPAP treatment.
The investigators will measure the improvement in SDB, as well as any change in symptoms, during a 1 week treatment with acetazolamide compared with 1 week of placebo (sugar pill). This study will help to provide data for longer term studies of treatment for SDB in patients who use opioids.
Read the detailed description
Patients who use chronic opioids for chronic pain daily for >3 months will be recruited. The investigators will study patients with established sleep disordered breathing (SDB; defined as an apnea-hypopnea index (AHI) >/= 10 events/hr). Patients with a prior diagnosis of SDB can enroll provided they can hold their CPAP treatment for the duration of the study. Persons with chronic lung or kidney disease will be excluded, along with those with heart failure, liver failure, kidney disease, medications affecting potassium levels, recreational opioid use, cancer pain, limited life expectancy, prisoners, pregnant women, psychiatric disease other than controlled mood disorders, and those unable to provide consent or cooperate with research procedures. Potential subjects will discuss the planned research protocol, risks, benefits, and alternatives with the study staff.
Once the individual has given written informed consent, they will be scheduled for a baseline study visit, which will begin in the early evening. Subjects will undergo a comprehensive history and physical exam, questionnaires examining sleep quality, daytime function, pain, and quality of life. The cold pressor test will be administered, which includes submerging the non-dominant hand in a 4 degree Celsius water bath, and reporting the onset of pain and maximal tolerable submersion time.
The subjects will be randomized into two groups: Group A will take acetazolamide 500 mg by mouth nightly for 1 week, followed by placebo (sugar pill) by mouth nightly for 1 week. Group B will take placebo (sugar pill) by mouth nightly for 1 week, followed by acetazolamide 500 mg by mouth nightly for 1 week. There will be a 2 week washout (i.e. no placebo or acetazolamide) between the treatments. The subjects and study staff will be blinded to the treatment that each subject is taking, in order to avoid introducing bias into the results. Study staff will be follow up with a phone call mid-week and will be available by phone if any issues arise.
At the end of each week (acetazolamide and placebo conditions), the subject will return for a follow up visit, during which they will undergo the same assessment tools as the baseline visit. They will then be instrumented for an overnight sleep study, which will include the application of electrodes to the scalp (electroencephalogram), beside the eyes (electro-oculogram), chin and legs (electromyogram). Elastic bands will be applied around the chest and abdomen, a pulse oximeter will be affixed to the finger, and airflow monitors placed just inside the nose and outside the mouth. The subject will then be allowed to sleep until the morning. Upon awakening, they will undergo a computer test of alertness.
- Conditions
- Sleep-Disordered Breathing, Obstructive Sleep Apnea, Central Sleep Apnea, Chronic Pain, Opioid Use
- Being tested
- Acetazolamide, Placebo
- Keywords
- Sleep apnea, Opioid, Lung
- Medical subject headings
- Sleep Apnea Syndromes, Sleep Apnea, Obstructive, Sleep Apnea, Central, Chronic Pain
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
AcetazolamideDrug
Acetazolamide 250 mg 2 capsules by mouth nightly
PlaceboOther
Sugar capsule manufactured to match encapsulated Acetazolamide 2 capsules by mouth nightly
| Study group | Role | What they receive |
|---|---|---|
| Placebo followed by acetazolamide | Experimental | Subjects will start with a 1-week PLACEBO regimen Day 1-7: Placebo (matching Acetazolamide) nightly
After a 2 week wash-out period, subjects will then cross-over to a 1-week ACETAZOLAMIDE regimen:
Day 1-7: Acetazolamide 500 mg nightly Receives: Drug: Acetazolamide; Other: Placebo |
| Acetazolamide followed by placebo | Experimental | Subjects will start with a 1-week ACETAZOLAMIDE regimen Day 1-7: Acetazolamide 500 mg nightly
After a 2 week wash-out period, subjects will then cross-over to a 1-week PLACEBO regimen:
Day 1-7: Placebo (matching Acetazolamide) nightly Receives: Drug: Acetazolamide; Other: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Apnea-hypopnea index, NREM Supine
The AHI is a measure of sleep apnea severity and is defined as the number of apneas (no breathing for 10+ seconds) and hypopneas (reduced breathing for 10+ seconds associated with a >=3% desaturation or cortical arousal) per hour of sleep. For the primary outcome, the study will evaluate the AHI during non-rapid eye movement sleep in the supine position.
Measured: 1 week
Secondary outcomes (1)
Apnea-hypopnea index, Total
The AHI is a measure of sleep apnea severity and is defined as the number of apneas (no breathing for 10+ seconds) and hypopneas (reduced breathing for 10+ seconds associated with a >=3% desaturation or cortical arousal) per hour of sleep. For the primary outcome, the study will evaluate the AHI during sleep in supine and lateral position.
Measured: 1 week
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted21 Sep 2023
- Study start18 Oct 2023
- Primary completion23 Dec 2025
- Study completion23 Dec 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Sleep-Disordered BreathingStudies of the same condition, open and under way.
- More trials run by University of California, San DiegoThe 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 2
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 39 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of California, San Diego
- Sponsor type
- University, hospital or other
- Collaborators
- National Heart, Lung, and Blood Institute (NHLBI)
- Responsible party
- Principal investigator, Jeremy Orr, M.D., University of California, San Diego
- Investigators
- Jeremy Orr, MD, Principal investigator, UC San Diego
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06043830
- Sponsor's protocol ID
- 201743.2
- Other IDs
- K23HL151880
- Acronym
- MORPHO
- Status last verified
- Mar 2026
- First submitted
- 12 Sep 2023
- Last updated
- 10 Mar 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- Yes
Study at a glance
From the registry record, last updated by the sponsor on 10 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Managing Opioid Related Sleep Apnea With Acetazolamide
- ClinicalTrials.gov ID
- NCT06043830
- Acronym / sponsor ID
- MORPHO / 201743.2
- Conditions
- Sleep-Disordered Breathing, Obstructive Sleep Apnea, Central Sleep Apnea, Chronic Pain, Opioid Use
- Keywords
- Sleep apnea, Opioid, Lung
- Phase
- Phase 2
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 39 participants (actual)
- Lead sponsor
- University of California, San DiegoUniversity, hospital or other
- Collaborators
- National Heart, Lung, and Blood Institute (NHLBI)
- Study start
- 18 Oct 2023 (actual)
- Primary completion
- 23 Dec 2025 (actual)
- Study completion
- 23 Dec 2025 (actual)
- First posted
- 21 Sep 2023 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Patients with chronic pain who use opioids appear to be at increased risk for breathing issues during sleep, termed sleep disordered breathing (SDB). Treatment of SDB often consists of use of a device during sleep that provides continuous positive airway pressure (CPAP) via a mask interface. However, this device is not effective or tolerated in all individuals. The goal of this study is to examine whether a medication called acetazolamide can improve SDB, as an alternative to CPAP treatment.
The investigators will measure the improvement in SDB, as well as any change in symptoms, during a 1 week treatment with acetazolamide compared with 1 week of placebo (sugar pill). This study will help to provide data for longer term studies of treatment for SDB in patients who use opioids.
Detailed description
Patients who use chronic opioids for chronic pain daily for >3 months will be recruited. The investigators will study patients with established sleep disordered breathing (SDB; defined as an apnea-hypopnea index (AHI) >/= 10 events/hr). Patients with a prior diagnosis of SDB can enroll provided they can hold their CPAP treatment for the duration of the study. Persons with chronic lung or kidney disease will be excluded, along with those with heart failure, liver failure, kidney disease, medications affecting potassium levels, recreational opioid use, cancer pain, limited life expectancy, prisoners, pregnant women, psychiatric disease other than controlled mood disorders, and those unable to provide consent or cooperate with research procedures. Potential subjects will discuss the planned research protocol, risks, benefits, and alternatives with the study staff.
Once the individual has given written informed consent, they will be scheduled for a baseline study visit, which will begin in the early evening. Subjects will undergo a comprehensive history and physical exam, questionnaires examining sleep quality, daytime function, pain, and quality of life. The cold pressor test will be administered, which includes submerging the non-dominant hand in a 4 degree Celsius water bath, and reporting the onset of pain and maximal tolerable submersion time.
The subjects will be randomized into two groups: Group A will take acetazolamide 500 mg by mouth nightly for 1 week, followed by placebo (sugar pill) by mouth nightly for 1 week. Group B will take placebo (sugar pill) by mouth nightly for 1 week, followed by acetazolamide 500 mg by mouth nightly for 1 week. There will be a 2 week washout (i.e. no placebo or acetazolamide) between the treatments. The subjects and study staff will be blinded to the treatment that each subject is taking, in order to avoid introducing bias into the results. Study staff will be follow up with a phone call mid-week and will be available by phone if any issues arise.
At the end of each week (acetazolamide and placebo conditions), the subject will return for a follow up visit, during which they will undergo the same assessment tools as the baseline visit. They will then be instrumented for an overnight sleep study, which will include the application of electrodes to the scalp (electroencephalogram), beside the eyes (electro-oculogram), chin and legs (electromyogram). Elastic bands will be applied around the chest and abdomen, a pulse oximeter will be affixed to the finger, and airflow monitors placed just inside the nose and outside the mouth. The subject will then be allowed to sleep until the morning. Upon awakening, they will undergo a computer test of alertness.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Quadruple blind (participant, care provider, investigator, outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Placebo followed by acetazolamide | Experimental | Drug: Acetazolamide, Other: PlaceboSubjects will start with a 1-week PLACEBO regimen Day 1-7: Placebo (matching Acetazolamide) nightly After a 2 week wash-out period, subjects will then cross-over to a 1-week ACETAZOLAMIDE regimen: Day 1-7: Acetazolamide 500 mg nightly |
| Acetazolamide followed by placebo | Experimental | Drug: Acetazolamide, Other: PlaceboSubjects will start with a 1-week ACETAZOLAMIDE regimen Day 1-7: Acetazolamide 500 mg nightly After a 2 week wash-out period, subjects will then cross-over to a 1-week PLACEBO regimen: Day 1-7: Placebo (matching Acetazolamide) nightly |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (4 listed)
- Age 18+
- Chronic pain
- Chronic opioid use (daily use for >3 months duration) with >/= 20 oral Morphine Equivalent Dose (MEqD) per day
- Apnea-hypopnea index >/= 10 events/hr (hypopnea definition: ≥ 3% desaturation or arousal criteria per American Academy of Sleep Medicine 2012 scoring rules)
Key exclusion criteria (21 listed)
- Use of opioids outside medical supervision (e.g. recreational use)
- Unable or unwilling to withhold any ongoing SDB treatment (e.g. CPAP) for the duration of the study
- Urgent need to initiate effective SDB therapy
- Chronic lung disease (other than well-controlled asthma)
- Active cardiac disease including heart failure, chest pain, or heart rhythm problems
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 |
|---|---|---|
| AcetazolamideAcetazolamide 250 mg 2 capsules by mouth nightly | Drug | Acetazolamide followed by placebo, Placebo followed by acetazolamide |
| PlaceboSugar capsule manufactured to match encapsulated Acetazolamide 2 capsules by mouth nightly | Other | Acetazolamide followed by placebo, Placebo followed by acetazolamide |
Primary outcome
Apnea-hypopnea index, NREM Supine
Time frame: 1 week
The AHI is a measure of sleep apnea severity and is defined as the number of apneas (no breathing for 10+ seconds) and hypopneas (reduced breathing for 10+ seconds associated with a >=3% desaturation or cortical arousal) per hour of sleep. For the primary outcome, the study will evaluate the AHI during non-rapid eye movement sleep in the supine position.
1 secondary outcome
Apnea-hypopnea index, Total
Time frame: 1 week
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 10 Mar 2026.
- Individual participant dataSharing planned: Yes
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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.
Jeremy Orr, MD principal investigator
UC San Diego
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2 study testing Acetazolamide in people with Sleep-Disordered Breathing and Obstructive Sleep Apnea, run by University of California, San Diego at 1 site 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 21 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: finished, as of the sponsor's last update on 10 Mar 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site 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 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
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?
Apnea-hypopnea index, NREM Supine (time frame: 1 week). 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 10 Mar 2026.