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Completed

NCT Number: NCT04726982

Optimal Dosage of Acetazolamide for OSA Treatment

Acetazolamide, a carbonic anhydrase inhibitor, has received some attention as potential treatment for obstructive sleep apnea (OSA). It produces a metabolic acidosis by excreting bicarbonate, thereby stimulating baseline ventilation. Evidence suggests that acetazolamide primarily improves ventilatory control instability (expressed as loop gain), which is an important contributor to the pathophysiology of OSA.

Few studies have assessed the efficacy of acetazolamide in patients with OSA. Since most of them had a small sample size and used different therapeutic dosages, clinical applications are currently limited. Therefore, this study aims to compare the effect of two acetazolamide dosages on the severity and pathophysiology of OSA.

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Key information

Conditions

Obstructive Sleep Apnea Acid-Base Imbalance Acidosis Apnea Dyssomnias Metabolic Diseases Nervous System Diseases Nutritional and Metabolic Diseases Pathologic Processes Pathological Conditions, Signs and Symptoms Respiration Disorders Respiratory Aspiration Respiratory Tract Diseases Sleep Apnea Syndromes Sleep Apnea, Obstructive Sleep Disorders, Intrinsic Sleep Wake Disorders

Age range

18 year–79 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 4

Primary location

Antwerp University Hospital

Edegem, Antwerp, 2650, Belgium

About this study

In this double-blind, parallel-group, controlled trial, eligible patients will be randomized into one of the following treatment arms: (1) placebo, (2) 250 mg of acetazolamide, or (3) 500 mg of acetazolamide. After 4 weeks, treatment outcome will be assessed by in-laboratory polysomnography. Additionally, arterial blood gas analysis and lung function tests will be performed before and during treatment.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • AHI between 15 and 65 events/hour
  • BMI < 35 kg/m²

Exclusion criteria

  • Craniofacial anomalies
  • Central sleep apnea (defined as central AHI > 25% of total AHI)
  • Contra-indications related to acetazolamide treatment
  • Hypersensitivity to sulphonamides or acetazolamide
  • Renal impairment, electrolyte imbalances, and/or adrenocortical insufficiency
  • Clinically significant metabolic, hepatic, and/or hematological disease
  • Chronic obstructive pulmonary disease
  • Closed-angle glaucoma
  • Conditions likely to affect OSA physiology: neuromuscular disease or other major neurological disorders, heart failure, or any other unstable major medical condition.
  • Intake of drugs that substantially stimulate or depress respiration, including benzodiazepines, opioids, theophylline, and pseudoephedrine
  • Inadequately treated sleep disorders other than OSA that would confound functional sleep assessment
  • Inability of the patient to understand and/or comply to the study procedures
  • Active psychiatric disease (psychotic illness, major depression, anxiety attacks, alcohol or drug abuse)
  • Pregnancy

Treatment and study plan

Acetazolamide

Drug

250 mg once daily

Other names: Diamox, ATC code: S01EC01

Placebo

Other

Once daily

Primary outcomes

  1. Apnea-hypopnea index (AHI)

    Time frame: 4 weeks

    Change in AHI (events/hour) from baseline to follow-up. The AHI is a measure of sleep apnea severity that encompasses the frequency of apneas (cessations in breathing) and hypopneas (reductions in airflow).

Secondary outcomes

  1. Pathophysiological traits

    Time frame: 4 weeks

    Changes in pathophysiological traits (Vpassive, Vactive, Arousal Threshold, Loop Gain) will be quantified as %Veupnea from polysomnography data using a validated algorithm.

  2. Percent responders

    Time frame: 4 weeks

    Treatment response will be defined as a reduction in AHI of ≥ 50%.

  3. Nocturnal oxygen saturation

    Time frame: 4 weeks

    Change in mean and minimal SaO2 (%).

  4. Oxygen desaturation index (ODI)

    Time frame: 4 weeks

    Change in ODI (events/hour) from baseline to follow-up. The ODI represents the average number of desaturation episodes (≥ 3%) per hour sleep.

  5. Arterial blood gas measurements

    Time frame: 4 weeks

    Change in pO2 (mmhg) and pCO2 (mmhg) from baseline to follow-up.

  6. Lung function parameters

    Time frame: 4 weeks

    Change in flow-volume curve from baseline to follow-up.

  7. Daytime sleepiness: Epworth Sleepiness Scale (ESS)

    Time frame: 6 weeks

    The ESS asks respondents to rate on a 4-point scale (0-3) their usual chances of dozing off or falling asleep while engaged in eight different activities. The ESS score (the sum of 8 item scores) can range from 0 to 24. The higher the ESS score, the higher that person's sleep propensity in daily life. A score higher than 10 indicates the presence of excessive daytime sleepiness.

  8. Sleep-related quality of life: Functional Outcome of Sleep Questionnaire (FOSQ-10)

    Time frame: 6 weeks

    This questionnaire is an abbreviated version of the original 30-item version. The FOSQ-10 consists of 10 items that are distributed among 5 subscales: general productivity (2 items), activity level (3 items), vigilance (3 items), social outcomes (1 item), and intimacy and sexual relationships (1 item). The questionnaire has a 4-point scale. The total score is calculated as the sum of the subscale means and can range from 5 to 20. The minimal important difference ranges from 1.7 to 2.0 points.

  9. Snoring intensity: Visual Analogue Scale (VAS)

    Time frame: 6 weeks

    A standard 10-point VAS ranging from 0 (no snoring) to 10 (extreme snoring) will be used to evaluate the subjective status of snoring during sleep. Heavy snoring corresponds to a snoring index of at least 7. A decrease of 3 points after treatment is considered significant. To be considered as an important reduction, snoring needs to reduce to an index that is no longer experienced as bothersome (i.e. < 3).

Other outcomes

  1. Incidence of adverse events

    Time frame: 6 weeks

    Safety and tolerability of study treatment.

Sponsors and collaborators

Lead sponsor

University Hospital, Antwerp

Other

Registry information

Official study title

Optimal Dosage of Acetazolamide for Obstructive Sleep Apnea Treatment: a Parallel-group, Double-blind, Placebo-controlled, Randomized Trial

Important dates

Study start
2021
Primary completion
2024
Study completion
2024
First posted
Jan 27, 2021
Registry last updated
Sep 24, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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