A new approach to drug delivery
“Drug delivery” (the process of sending an active drug compound to the bit of the body where you want it to work it’s magic) is often the hardest bt of drug design. Effective drug delivery reduces side effects, improves patient compliance and drug efficacy and helps target treatments at the patients who will benefit most.
A lot of multi-million dollar drugs don’t work as well as they could because of delivery problems. People like pills, but not all drugs go into a pill formation. Injections and invasive delivery are less popular.
Here’s a possible breakthrough developed in Belfast:
Microneedle arrays are minimally-invasive devices that, painlessly and without drawing blood, penetrate the skin’s outermost barrier, the stratum corneum. First described in the patent literature in the late 1970s, it was not until advances in the microelectronic industry in the late 1990s made their fabrication possible that microneedles became a realistic proposition. Microneedle arrays consist of multiple projections (up to 2000 per square centimetre) on a supporting baseplate. Their heights can vary from tens of micrometers up to a few millimetres.
The skin has evolved into an almost impermeable barrier to topically-applied substances. Normally only small relatively lipophilic permeants can cross the skin at therapeutically-useful levels. By breaching the stratum corneum barrier and creating aqueous pores, delivery of a wide range of therapeutic molecules across the skin becomes possible.
Microneedles have historically been made from silicon and metal due to their origin in microelectronics. However, recently a wide range of biocompatible and biodegradable polymeric materials have been employed in microneedle fabrication. Novel technology developed by Dr Ryan Donnelly and Professor David Woolfson at the School of Pharmacy, Queen’s University Belfast is based on microneedles prepared from swellable polymeric materials that are hard in the dry state, but rapidly imbibe skin interstitial fluid to form continuous unblockable conduits between a drug reservoir and the viable skin. This creates the possibility for transdermal and in-skin delivery of a wide range of therapeutic substances at controllable rates. Examples include vaccines, insulin, gene delivery vectors and water soluble drugs that must normally be given at multiple times each day.
People in the developing world stand to benefit greatly from commercialisation of this technology, since vaccination would now be risk-free; no possibility of needlestick injuries, no-reuse or disposal issues, since the system is self-disabling, becoming soft in skin, thus preventing re-insertion. Patients who need to take regular injections and those who take multiple drugs throughout the day would also benefit from microneedle-based drug administration. The worldwide vaccine market is worth US $21 billion annually, while the transdermal drug delivery market is worth US $20 billion each year, despite being based on only around 20 drugs. Microneedle technology stands to seize a substantial share of both markets over the next 2-5 years, to the benefit of UK industry and patients worldwide.
The Queen’s University Belfast microneedle technology has been developed over the period 2007-2012 through funding from the Biotechnology & Biological Sciences Research Council, the Engineering & Physical Sciences Research Council, the Wellcome Trust and the Royal Society and is currently undergoing commercial development by two leading pharma companies. The vital next stage in development is design and validation of methods for large scale industrial manufacture and human clinical trials.