Researchers Test Cheek Films for Needle-Free GLP-1 Delivery

A research team at University College Dublin has developed thin films that dissolve inside the cheek to deliver GLP-1 peptides without needles. The films use a natural polymer called pullulan and successfully delivered measurable amounts of a GLP-1 analogue in laboratory testing. (Karki et al., Carbohydrate Polymers, February 2026. PMID: 41831981)

The buccal route means absorption through the cheek lining. Blood vessels there can pull peptides directly into circulation, bypassing the digestive system that typically breaks down these compounds. The challenge has always been getting enough peptide through to make it worthwhile.

How the film technology works

The team created a two-layer film design. The backing layer prevents the peptide from leaking into the mouth. The drug layer contains the GLP-1 analogue plus enhancers that help it cross through cheek tissue. Both layers are made from pullulan, a water-soluble polymer derived from yeast that's already used in food products.

When placed against the inside of the cheek, the film dissolves over several hours. The researchers tested different formulations and found that adding specific enhancers increased peptide absorption by 3.5 times compared to films without enhancers.

The films remained stable for at least 6 months when stored in proper conditions. They also passed initial safety tests on human cheek cells in lab cultures.

The bioavailability problem

Getting peptides through the cheek isn't new. The problem is efficiency. Injectable semaglutide and tirzepatide have nearly 100% bioavailability because they go straight into tissue. Oral versions struggle to reach even 1% bioavailability due to digestive breakdown.

Buccal delivery sits somewhere in between. The Dublin study found that their best film formulation achieved bioavailability numbers in the low single digits. Better than oral, but still requiring much higher doses than injections to get the same effect.

The researchers estimate that a practical buccal film would need to contain 5 to 10 times the peptide dose of an equivalent injection. That's actually reasonable compared to some oral formulations that require 50 to 100 times higher doses.

Real-world obstacles remain

This was laboratory and cell culture work. No human trials yet. The films worked in artificial saliva and on isolated cheek cells, but actual human mouths are more complex environments.

Saliva flow, eating, drinking, and talking all could interfere with the absorption process. The films need to stick to the cheek for several hours to work properly. That's a significant practical barrier.

Manufacturing is another issue. Making consistent films with precise peptide doses is more challenging than filling vials for injection. The peptide also needs to remain stable during film production and storage.

Why this matters for peptide users

Injection anxiety is real. Many people who could benefit from GLP-1 therapies avoid them because of needle phobia. Others travel frequently and find weekly injections inconvenient.

A buccal film that works reliably could open these therapies to a much larger group of people. The convenience factor alone would be significant. No needles, no refrigeration during short trips, no injection site reactions.

The dosing flexibility could also be interesting. Films could potentially be cut for dose adjustments, though this would need careful validation for safety and effectiveness.

Timeline and next steps

The research team didn't announce immediate plans for human trials. That usually requires partnership with a pharmaceutical company and regulatory approval. The timeline from promising lab results to market availability typically runs 5 to 10 years for novel delivery methods.

Other groups are working on similar approaches. Oral GLP-1 formulations are already in clinical trials, though they use different enhancement strategies. The race is on to find the first practical needle-free option that maintains reasonable dosing requirements.

For current users of injectable GLP-1 medications, this remains future technology. But it represents the kind of innovation that could eventually make these powerful peptides accessible to people who currently can't or won't use injections.