Delivering the goods
In the late aughts, John Hoekman was a graduate student in the University of Washington’s pharmaceutics program, studying nasal drug delivery. In his experiments, he noticed that drugs distributed differently, depending on the region targeted – aiming for the upper nasal cavity led to a spike in absorption.
The results convinced Mr. Hoekman to stake his future on nasal drug delivery.
In 2008, while still in graduate school, he started his own company, now known as Impel Pharmaceuticals. In 2021, Impel released its first product: Trudhesa, a nasal spray for migraines. Although the drug itself – dihydroergotamine mesylate – was hardly novel, used for migraine relief since 1946 (Headache. 2020 Jan;60[1]:40-57), it was usually delivered through an intravenous line, often in the ED.
But with Mr. Hoekman’s POD device – short for precision olfactory delivery – the drug can be given by the patient, via the nose. This generally means faster, more reliable relief, with fewer side effects. “We were able to lower the dose and improve the overall absorption,” said Mr. Hoekman.
The POD’s nozzle is engineered to spray a soft, narrow plume. It’s gas propelled, so patients don’t have to breathe in any special way to ensure delivery. The drug can zip right through the nasal valve into the upper nasal cavity.
Another company – OptiNose – has a “bidirectional” delivery method that propels drugs, either liquid or dry powder, deep into the nose.
“You insert the nozzle into your nose, and as you blow through the mouthpiece, your soft palate closes,” said Dr. Hindle. With the throat sealed off, “the only place for the drug to go is into one nostril and out the other, coating both sides of the nasal passageways.”
The device is only available for Onzetra Xsail, a powder for migraines. But another application is on its way.
In May, OptiNose announced that the FDA is reviewing Xhance, which uses the system to direct a steroid to the sinuses. In a clinical trial, patients with chronic sinusitis who tried the drug-device combo saw a decline in congestion, facial pain, and inflammation.
Targeting the brain
Both of those migraine drugs – Trudhesa and Onzetra Xsail – are thought to penetrate the upper nasal cavity. That’s where you’ll find the olfactory zone, a sheet of neurons that connects to the olfactory bulb. Located behind the eyes, these two nerve bundles detect odors.
“The olfactory region is almost like a back door to the brain,” said Mr. Hoekman.
By bypassing the blood-brain barrier, it offers a direct pathway – the only direct pathway, actually – between an exposed area of the body and the brain. Meaning it can ferry drugs straight from the nasal cavity to the central nervous system.
Nose-to-brain treatments could be game-changing for central nervous system disorders, such as Parkinson’s disease, Alzheimer’s, or anxiety.
But reaching the olfactory zone is notoriously hard. “The vasculature in your nose is like a big freeway, and the olfactory tract is like a side alley,” explained Mr. Hoekman. “It’s very limiting in what it will allow through.” The region is also small, occupying only 3%-10% of the nasal cavity’s surface area.
Again, POD means “precision olfactory delivery.” But the device isn’t quite as laser focused on the region as its name implies. “We’re not at the stage where we’re able to exclusively deliver to one target site in the nose,” said Dr. Hindle.
While wending its way toward the olfactory zone, some of the drug will be absorbed by other regions, then circulate throughout the body.
“About 59% of the drug that we put into the upper nasal space gets absorbed into the bloodstream,” said Mr. Hoekman.
Janssen Pharmaceuticals’ Spravato – a nasal spray for drug-resistant depression – is thought to work similarly: Some goes straight to the brain via the olfactory nerves, while the rest takes a more roundabout route, passing through the blood vessels to circulate in your system.