Patients don't like getting needles, nor do clinicians like having to keep protein-based vaccines cold at all times. A new polymer wafer – which dissolves when placed under the tongue – could address both issues.
First of all, there already are some drugs which are delivered via tablets that the patient places beneath their tongue. As the tablet dissolves, the medication is absorbed through the sublingual mucous membrane on the underside of the tongue, subsequently entering the bloodstream.
In the case of many protein-based vaccines, however, the drug molecules are too large to quickly make their way past the membrane. Because the tablet doesn't stay in precisely one spot until it completely dissolves, the molecules simply don't have enough time to get through. Additionally, because those molecules are also quite fragile, they often have to be continuously stored at very cold temperatures in order to remain intact and functional.
That's where the experimental new wafer comes in.
Designed by a University of Minnesota-led team of scientists, it's made up of two polymers – carboxymethyl cellulose (CMC) and seaweed-derived alginate – to which a vaccine is added. The sticky CMC allows the wafer to adhere to the sublingual membrane long enough for a high concentration of the drug molecules to make their way through, while the alginate protects and preserves those molecules, allowing them to be stored at room temperature.
In lab tests conducted on mice, the wafer has successfully been used to sublingually deliver human immunodeficiency virus proteins, which might someday constitute part of an HIV vaccine. The technology could potentially also be used to deliver vaccines for other illnesses, including COVID-19.
"If we continue this line of work, it can bring us to a point where we will have vaccines – they could be based on DNA, RNA, proteins – that can be stored without refrigeration and easily delivered under the tongue at the sublingual site," says the lead scientist, U Minnesota's Assoc. Prof. Chun Wang. "They will be quickly disseminated throughout the world because they don’t rely on certain equipment and preservation and all of that stuff. This will be particularly good for low-resource regions of the world, even in America – rural areas that are lacking certain essential facilities and infrastructure."
A paper on the research – which also involved scientists from the Mayo Clinic, University of Texas and MD Anderson Cancer Center – was recently published in the Journal of Controlled Release.
Source: University of Minnesota
