New Research Shows The Importance of Surface Tension in Medication

According to new research, an overlooked parameter may make it easier for drug makers to identify what solutions may be most effective for liquid oral, nasal and ophthalmic drugs.

“Liquid drugs are tested for all kinds of things beyond just what the drug does and how it’s absorbed,” explains Ronny Priefer, professor of pharmacy at Western New England University in Springfield, MA. “The solution’s pH, viscosity, density and other factors play a role in how effective the solution will be.”

“But one thing that we’ve never really considered is the surface tension,” he says.

Surface tension is the elastic tendency of a fluid surface which makes it acquire the least surface area possible; it’s what makes a water drop hang from the faucet when you turn off the tap.

“We found that the surface tension is important when you’re looking at a liquid solution for the eye or nose, or one that’s taken orally.”

With colleagues Kimberly Han and Osakpolor Woghiren, Priefer measured surface tension of over 25 over-the-counter liquid oral medications, nasal sprays and eye drops. They found that each oral formulation was at or above the surface tension of fluids in the stomach. Nasal formulations all had surface tension beneath those of the nose – to allow for greater spreading. Eye drops varied depending on the purpose of the drug: solutions to treat red eye had surface tensions less than that of tears, presumably to aid spreading. Solutions for treating dry eye had surface tensions greater than tears, allowing for better lubrication.

“This research tells pharmacy companies that, if you’re developing a drug in a liquid form, you need to consider the surface tension to know if it will be effective or not,” says Priefer. “This can really speed up advancement.”

The study, “Surface Tension Examination of Various Liquid Oral, Nasal and Ophthalmic Dosage Forms,” was published last month in Central Chemistry Journal

Source Contact Information

Western New England University
Professor of Medicinal Chemistry