Medicated nails? Spray-on patches? How pharmaceutical medical devices come to market

Above: four important medical devices: an MRI scanner, an insulin pump, a scalpel and a hearing aid

Medical devices are instruments or machines that are often used to diagnose, prevent, monitor or treat diseases. Examples of medical devices include MRI scanners, insulin pumps, scalpels and hearing aids. Unlike new medicines, which go through three phases of clinical trials before becoming commercially available, new medical devices are classified into groups based on their risk levels, with high-risk devices undergoing rigorous testing in clinical trials which may not be necessary with low-risk medical devices.

Professor Stuart Jones, Director of the Centre for Pharmaceutical Medicine Research, is developing three medical devices that focus on administration of active ingredients into and through the skin. Because of the low-risk nature of the active ingredients and the devices, these innovative devices can be translated into commercially available products in a relatively short period of time.

Medspray

Medspray – known as ‘patch-in-a-can’ – is an aerosol system used for drug delivery that, when sprayed, forms into a microfine film on the skin. 

Professor Jones developed the device as a solution to problems associated with traditional medical patches that can be uncomfortable, fall off and show poor delivery efficiency. Medspray is a pressurised bottle that sprays a film onto the skin that self-forms into a patch. The new patch has enhanced drug delivery as it has been thermodynamically-optimised to maximise permeation and penetration of the medicine through the tissue. 

Because the patch is sprayed onto the skin, it also forms around the body hair, meaning it sticks to the skin more effectively. On top of this, the patch is transparent – an element that consumers have appreciated.

Research into the device was funded by a company named MedPharm, which was spun out of King’s by Professor Marc Brown in 1999. Medpharm own the patent, and have licenced Medspray to three other companies, who are currently testing it in clinical trials with three different agents.

Vitamin D Phosphate patch

Vitamin D is an essential nutrient for our body, boosting our mood, immune system, muscle function, and helping ward off diseases such as cancer. Most people, even those in hot countries, are Vitamin D deficient due to sedentary lifestyles that keep them indoors and away from the sun. Oral Vitamin D oral supplements have limited effectiveness because the nutrient is fat-soluble, meaning it dissolves in fats and oils rather than water. Because of this, oral supplements can only be properly absorbed by the gut after a heavy, oil-rich meal.

Professor Jones and his lab set out to create a transdermal patch that could deliver Vitamin D directly into the bloodstream. Simply loading the patch with Vitamin D wasn’t effective because the barrier of the skin prevented this and because vitamin D gets stuck in the outer layers of the skin. Therefore, they modified the Vitamin D molecule by adding a phosphate group. By doing this, they enabled Vitamin D to pass through the skin and into the blood stream.

Surprisingly, they discovered that the body was behaving in the same way it would if the sun was shining on it. In other words, the Vitamin D phosphate was able to metabolise in the skin. A binding protein travelled to the surface of the skin and to carry the Vitamin D molecule away into the bloodstream. The patch was affectively ‘mimicking the sun’. In laboratory testing the  Vitamin D phosphate patch was able to deliver almost 300 times the amount of vitamin D through the skin compared to a marketed Vitamin D patch. 

Above: a diagram showing how the Vitamin D phosphate patch works (right) in comparison with a generic Vitamin D patch (left)

The patch technology has been patented, passed toxicology testing and is currently undergoing a clinical trial on humans, with results expected in August. If successful, the product will go straight onto the market, being able to be bought by anyone as a supplement.

Medicated Artificial Nails

If you regularly play sports, you could be suffering from a common fungal infection called onychomycosis. 

Usually induced by nail damage, it’s a fungal infection in the nail that is very difficult to treat and afflicts perhaps 10% of the world’s population, often for their entire lives. 

One currently available treatment involves swallowing a tablet that contains agents that then travel through your bloodstream and penetrate the nail from underneath. Another involves applying medication to the surface of the nail from the outside.

The problem is that the nail is one of the trickiest barriers in the body to penetrate. Current treatments can take 6-12 months and has a relapse rate of 30-50%. Usually harmless, the infection can become invasive if the immune system is supressed due to diseases such as diabetes, HIV or cancer.

Professor Jones has been investigating ways of penetrating the nail for over a decade. He began experimenting with the chemical compound sodium hydrogen sulfide – a colourless gas that smells like rotten eggs. The molecular size of hydrogen sulfide is incredibly small, so it can penetrate the nail very effectively and is also a potent antifungal, killing the organisms rapidly.

Above: a diagram showing how the medicated artificial nail attaches to the infected nail

They proposed a simple delivery method: an artificial nail that covers the infected nail for a week, killing the disease in a one-off treatment. And although hydrogen sulfide has an aroma, it’s used in such small quantities that the smell isn’t noticeable.

Professor Jones is currently exploring manufacturing options to produce the nail is a range of stock sizes that could be easily bought, for example, from a pharmacy.

Learn more about Professor Jones' research.

Find out more about the Centre for Pharmaceutical Medicines Research.