Optimisation of microneedle insertion and understanding the implications of repeat application as tools to support translation

Traditional pharmaceutical drugs are small molecules that treat the symptoms of a disease. Biopharmaceuticals are larger molecules, for example, peptides and proteins, which target the underlying mechanisms and pathways of a disease that are not accessible with traditional drugs. Recently, there have been rapid and revolutionary developments in this field of biotechnology.

Therapeutic peptides and proteins are expected to be used increasingly as vaccines and as treatments for cancer, high blood pressure, pain, blood clots and many other illnesses. However, one of the major challenges to successful clinical use of these so-called "biotech" molecules is their efficient delivery to the site of action. The body breaks these medicines down when they are swallowed and they are generally not well-absorbed into the blood.

As a result, they have to be given frequently by injection, which is painful and means that these drugs are usually only administered in hospital. Long-acting formulations of small molecules, increasingly to the fore in treating HIV and TB, must also be injected. The COVID-19 pandemic has greatly increased the need for self-administration of injectables at home, away from healthcare settings, where transmission can have dire consequences.

Complexities of storage, distribution and administration, needle phobia and the difficulty of domestic disposal of potentially-contaminated sharps all contribute to an urgent need for alternative delivery modes for injectable drugs/vaccines. Similarly, development of blood-free diagnostic systems is a major priority.

We have developed a novel type of transdermal patch that by-passes the skin's barrier layer, which is called the stratum corneum. The patch surface has many tiny needles that pierce the stratum corneum without causing any pain - The sensation is said to feel like a cat's tongue. These needles either dissolve quickly, leaving tiny holes in the stratum corneum, through which medicines can enter the body, or swell, turning into a jelly-like material that keeps the holes open and allows continuous drug delivery.

Our unique technology could potentially revolutionise the delivery of peptides and proteins, as well as that of long-acting small molecules that cannot currently be delivered across the skin. Notably, we have also found that our swellable microneedles can extract fluid from the skin. This permits us to monitor the levels of medicines and markers of disease without actually taking blood samples.

In the UK, the NHS stands to benefit from reduced costs due to shorter hospital stays and reduced occurrence of inappropriate dosing. Ultimately, health-related-quality-of-life will be enhanced through improved disease control, rapid detection of disease and dangerously high or low levels of medicines, facile monitoring of compliance with prescribed dosing and detection of illicit substances in addicts or vehicle drivers.

Preterm neonates will derive great benefit from the marked increase in monitoring frequency permitted, as will elderly patients being treated with multiple medicines. At-home treatment/diagnosis, keeping people away from healthcare settings, will also help reduce spread of COVID-19 to vulnerable in-patients and healthcare workers.

We have attracted considerable interest and funding from industry to investigate our technologies for a range of applications. However, to facilitate the commercialisation process and maximise value to the UK, it is now essential to develop methods for rationalised skin application of the microneedles such that they are always applied to every patient in the same way every time and that their efficacy is guaranteed.

We will also study, for the first time under industry-standard conditions, repeat application of our microneedles to mimic normal use and to demonstrate safety. Ultimately, commercialisation of the technology will be the primary route by which UK industry, the NHS and patients will derive benefits