Gently administering drugs with a membrane containing active ingredients

Interview with Dr. Luciano F. Boesel, Group Leader for "Medical Textiles" at Swiss Federal Laboratories for Materials Science and Technology (EMPA)

Injections are not popular with either children or adults. For years, researchers have therefore been looking for a way to administer drugs in a gentler manner. Swiss scientists now developed a membrane that releases active ingredients under ultraviolet light. It could revolutionize how drugs and vaccines are being administered.


Photo: Luciano F. Boesel

Dr. Boesel is interested in the development of non-invasive body-monitoring sensors based on optical fibers, fluorescent textiles, and responsive membranes; © EMPA

In this interview with, Dr. Luciano Boesel, Group Leader for “Medical Textiles“, Protection and Physiology at the Swiss Federal Laboratories for Materials Science and Technology (EMPA), speaks about controlling drug administration and the potential use of the membrane in connection with adhesives.

How did you and your team come up with the idea of administering active ingredients via a membrane?

Dr. Luciano Boesel:
We developed the membrane in cooperation with the Clinic of Neonatology of the University Hospital Zurich. The physicians at this facility initiated this project. Ultimately, the idea originated in the intensive care for newborn babies. In some cases, these newborns require caffeine to prevent respiratory arrest. This is typically done via tubes or by administering injections. Since these children are very sensitive, the injections cause additional stress.

The idea to develop a gentler method of administration therefore originated with the Clinic. The development of an alternative method was in the hands of our laboratory. We did not reinvent the adhesive tape. There are already established products for transdermal delivery, for instance estrogen or nicotine patches that release their active ingredients when they come in contact with the skin. Instead, we created a membrane that can be used with a conventional adhesive tape and controlled via UV light. Testing with the membrane in turn took place at the University Hospital.

What is the disadvantage of an injection?

There are three fundamental disadvantages. For starters, many people think injections are painful. In addition, when you use injections, you inject a very large dose of the active ingredient into the body. The drug is not optimally dosed. Initially, the concentration is very high and subsequently decreases very quickly. The drug or vaccines therefore need to be administered via several injections until the active ingredient works fully. This can minimize the drug’s effectiveness. This is why consistent drug dosing over several hours that can be individually controlled would be preferable.
Photo: Caffeine permeability of the membrane

Visible light is not able to activate the functional group (left), whereas UV light can do so (right). As a result it is possible to create a plaster which, upon UV-activation, can deliver a dose of medication; © EMPA

How does the membrane you developed work?

Drugs diffuse through a membrane to the inside via the skin. The drug delivery rate can also be controlled. The membrane we developed is light sensitive and contains molecules, so-called spiropyrans that make them more permeable when they are illuminated with UV light. The delivery itself is regulated by irradiating the membrane with different colors. In contrast, the membrane is less permeable when it is being irradiated with white light.

How is the delivery of the active ingredient regulated?

The spiropyrans change when you irradiate the membrane with UV light. Polar bonds are being produced. Hydrophilic molecules that dissolve in water subsequently diffuse easier through the pad. This process can even be controlled over several hours. When you irradiate the membrane with white light the spiropyrans are deactivated again and restored to their original state. That is to say, they are water-repellent again. Drugs that are then dissolved in the water diffuse less or no longer through the membrane.

Can the adhesive tape be used for all types of active ingredients?

Our project primarily focuses on the delivery of caffeine to newborns to prevent respiratory arrest. However, it is conceivable that the membrane can also be used for other drugs such as theophylline or lidocaine for instance. Corresponding experiments are already being conducted on this. These are hydrophilic agents similar to caffeine. The membrane we developed in our Institute is suitable for all drugs that are able to diffuse through the skin. Drug delivery cannot just be specifically controlled, but the membrane can also be adjusted to the respective active ingredient. To do this, only the composition needs to be changed.
Photo: pink bird on top of the membrane

A membrane irradiated through a mask. A pink bird is visible, showing where the UV light has reached the membrane and activated it; © EMPA

What other challenges are you meeting with your research project?

One of the main problems that still need to be solved is the low permeability of skin in adults. Depending on the skin type, drug absorption inside the body is reduced. One example of this would be insulin, which only permeates the skin very slowly or not at all. You subsequently need to apply methods that locally increase skin permeability. Many research institutes are involved in this subject.

Molecules that are not soluble in water could also be delivered through the membrane. In this case, it would need to be individually adjusted to the drug.

Are you currently working in this direction?

We are presently not testing any other drugs. We have initially decided on caffeine and tested different approaches with it. We have developed four different types of membranes. One of them is almost exclusively suited for hydrophilic molecules. The other three can be adapted so that hydrophobic drugs could be administered. Yet essentially this increased area of application only requires a simple modification in the chemical composition of the membrane. You would need to alter the membrane material and insert polymers that are better suited for hydrophobic molecules. Spiropyrans do not play a role in this.
Photo: Melanie Günther; Copyright: B. Frommann

© B. Frommann

The interview was conducted by Melanie Günther and translated from German by Elena O'Meara.