Many diseases rely upon medication for their treatment or cure. Yet, modern day drug therapy continues to be based upon 20th century principles. We get ill, we take a pill and then attempt to go about our daily lives, sometimes suffering from unpleasant side effects. On the flip side, a large number of potentially life-saving treatments never get to market, or are removed from sale, because of their questionable safety profiles.
But why does this happen? Firstly, most drugs are by nature non-selective, since their sites of action are present in many tissues in the body. Although this can be beneficial, it can also be problematic, especially if the drug has two opposing outcomes; for example, good in the brain, bad in the heart. Secondly, drugs are not binary. That is, they are present in the body until metabolised or eliminated and cannot be simply switched ON and OFF. As such, it could be argued that modern drug therapy is like taking a sledgehammer to crack a nut.
So how can we improve upon this? The key is to produce drugs whose activity can be delivered to the right place in the body at the right time. Light provides an excellent way of doing this, since it is relatively non-toxic and has unrivalled precision in space and time. To place drugs under light control, we can take inspiration from nanotechnology, the study of atoms that formed the basis of this year’s Nobel Prize in Chemistry (Professor Sir J Fraser Stoddart was one of the recipients for work performed during his time at the University of Birmingham). Notably, a tiny ‘molecular switch’ can be easily incorporated into the backbone of many drugs, allowing activity to be changed following illumination. The field- termed ‘photopharmacology’- has so far succeeded in producing light-activated anti-diabetics, anaesthetics, painkillers, antibiotics and chemotherapeutics amongst others. Importantly, these are all based on generic drugs whose safety profiles are well studied, and which can be produced in bulk for just a few pence. However, a number of challenges remain. For example, can the minor changes to drug structure lead to unintended toxicity? Would people really want to be implanted with micro light emitting devices (µLEDs) capable of directing drug to its target? Are drug companies likely to be interested when the re-purposed drugs may not be commercially-exploitable?
Certainly, increasing evidence suggests that the modifications needed to produce light-activated drugs are not in themselves toxic, although more extensive work is warranted. Smart medicine is predicted to be widespread in the future where individuals are implanted with bioengineered devices that give a continuous readout of health status and incorporate µLEDs. Industry shareholders will be more difficult to convince, but universities are now expert at setting up small spin-off companies and marketing their wares through licensing deals. For example, Alta Innovations at the University of Birmingham has an extensive track record in this arena.
Whether or not light-activated drugs become the mainstay of disease therapy, they still provide the foundations for refining the safety and efficacy of drugs. This is necessary if we want to be able to treat diseases more effectively, improving quality of life and saving healthcare budgets.