Incannex Healthcare’s IHL-42X lowered apnoea hypopnea index score in OSA sufferers during clinical study

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By Lorna Nicholas - 
Incannex Healthcare ASX IHL 42X obstructive sleep apnoea phase 2 clinical trial OSA AHI

During a phase 2 trial, IHL-42X was found to reduce obstructive sleep apnoea by more than 80% in 25% of participants, and 50.7% on average on the apnoea hypopnea index.


Incannex Healthcare (ASX: IHL) has found its drug IHL-42X reduced the apnoea hypopnea index (AHI) score at the three doses it was given to obstructive sleep apnoea (OSA) patients during a phase 2 clinical trial.

Incannex developed IHL-42X with two primary pharmaceutical ingredients tetrahydrocannabinol (THC) and acetazolamide to target different aspects of OSA.

Advantageously, during the study, it was the lowest dose IHL-42X, (2.5mg of THC and 125mg of acetazolamide), which performed better than the mid and high doses.

At the lowest dose, the AHI score was reduced by an average of 50.7% compared to baseline. Of the participants, 25% displayed a greater than 80% reduction in AHI at the same dose.

This means that when treated with IHL-42X, a patient’s breathing was interrupted less frequently during sleep.

“This supports Incannex’s hypothesis that IHL-42X is an effective treatment for OSA,” the company stated.

“The observation that low dose IHL-42X was the most effective at reducing AHI is encouraging for the development of IHL-42X as a pharmaceutical as a lower dose will reduce the risk of side effects and the cost of goods.”

An added advantage of the lower dose meant that plasma THC levels the morning after an IHL-42X dose were under the thresholds for impaired driving.

As well as reducing the AHI score during the trial, the low dose IHL-42X reduced oxygen desaturation index (ODI) by 59.7% compared to the baseline.

This resulted in better sleep quality and also reduced cardiovascular stress.

Obstructive sleep apnoea (OSA)

OSA occurs when a person’s upper airway narrows during sleep and interferes with breathing.

It results in decreased oxygen uptake and poor-quality sleep.

When left untreated, OSA can lead to serious long-term adverse health outcomes including hypertension, cardiovascular disease, heart attack, cognitive impairments, anxiety, depression, irritability and day-time fatigue, which can increase the risk of accidents.

There are currently no pharmacotherapy (drug) treatments for OSA. The current standard of care involves a continuous positive airway pressure (CPAP) machine, which has low patient compliance because its lack of comfort reduces tolerability.

Should IHL-42X continue to show positive safety and efficacy results in clinical trials, Incannex says it could be a viable alternative and replacement to the CPAP machine.

The global annual market for OSA detection and treatment using CPAP and other breathing aids is approximately US$10 billion per annum.

Incannex’s strategy is to present IHL-42X as a viable pharmaceutical alternative.


IHL-42X’s main ingredients THC and acetazolamide target different aspects of OSA.

Alone, THC dampens afferent vagal feedback, dilates the upper airway and stabilises respiratory patterns.

THC is already approved in the US for treating HIV/AIDS induced anorexia, and chemotherapy induced nausea and vomiting.

Acetazolamide is carbonic anhydrase inhibitor and is currently used to treat glaucoma, epilepsy, and altitude sickness. It has been demonstrated as effective in treating OSA.

When combined, the drugs act synergistically to combat OSA to a far greater extent than each formula alone, and Incannex has filed a patent for IHL-42X with the international patent examiner already calling the drug “novel and inventive”.