New research shows proteinaceous foam that forms nests of the túngara frog (Engystomops pustulosus), a native of Trinidad, can encapsulate a variety of hydrophobic and hydrophilic compounds and release them steadily over long periods, providing an improved drug delivery system that could help to combat the rise of antimicrobial resistance.

The results were published this week in the article, “Frog nest foams exhibit pharmaceutical foam-like properties” in the journal, Royal Society Open Science.

This work shows that the highly stable and biocompatible foam retains desirable physical and chemical properties even when removed from its natural location and may be applied as a drug delivery system in a range of pharmaceutical applications. The authors recreate the frog nest foam in bacteria demonstrating the possibility of scaling up its production.

Since the 1970s foams have been used in cosmetics and therapeutics as delivery systems but conventional synthetic foams have limited stability and biocompatibility and need added oxygen.

Stable foams are rarely produced in the natural world, but some frogs produce foam to protect their eggs and larvae from predators, parasites, and ultraviolet rays, as well as to provide them optimal humidity, oxygen, and temperature. These frog nest foams can be stable for up to ten days in tropical climates and are gentle on the sensitive amphibian skin rendering them highly biocompatible.

The researchers from Queen’s University Belfast, the University of Strathclyde, and the University of Glasgow show that the foam can benefit topical, vaginal, and rectal drug delivery by providing a sustained release delivery system that minimizes the risk of infection, allergy, and antimicrobial resistance.

“This controlled release and stable compounds have huge implications for drug delivery. One practical example could be with burn treatment where the foam would enable the drugs to be delivered under the bandage over a longer period, without need to remove the bandages frequently, which would reduce the chance of infection,” says senior author of the paper, Dimitrios Lamprou, PhD, from the School of Pharmacy at Queen’s University Belfast. “Organic structures are also less irritable and less likely to cause allergies to human skin. Further testing is needed, but we are excited about the prospect of this novel drug delivery which could be used for proteins or siRNA.” 

Paul Hoskisson, PhD, at the University of Strathclyde and co-corresponding author on the paper says, “This is the first time an amphibian foam has been used for drug delivery. It should give us a nice, safe delivery vehicle that can be administered to patients without any fear of making them sick, unlike many of the other synthetic delivery vehicles.”

In future studies, the team intends to reproduce the exact foam in the lab and test more drugs to see which drugs lend themselves to this new system of drug delivery.