Wednesday, 30 November 2011

Drug Delivery, targeted therapeutics and the future of medicine

NSB went to a fascinating public lecture at the University of Nottingham today. Part of the “New Science Sessions” series, the talk was titled “Drug Delivery, targeted therapeutics and the future of medicine” and presented by two PhD students - Eleanor Grimes and Jennie Lord.

Slightly scary title, it has to be said, but the inclusion of “and the future of medicine” certainly gives them a lot of scope. It’s a bit like a politician giving a talk called “Housing Benefit, targeted welfare and what might happen in Europe over the next hundred years”.

But anyway.

Jennie Lord began the presentation and explained that there are many ways that drugs can be administered (injection, absorption through the skin, orally etc) and that, of these, oral administration is preferred for its obvious attractions of ease, convenience and relatively low cost. A show of hands in the audience indicated that there were far fewer people who would be happy about taking a weekly injection than there were people who would be happy with a weekly tablet.

The example of Ibuprofen was given. This is a drug that blocks hormones that cause pain, welling and inflammation. When given via a tablet, it takes approximately two hours before the peak effect is achieved. Now, the pain relief would come a lot sooner if Ibuprofen were given via injection, but that would be more expensive, more painful (oh, the irony) and would probably require a trip to the doctors.

Having said that, oral administration of medicine does have its problems, particularly in relation to the potential attack by acidic gastric juices and enzymes.

Wouldn’t it be wonderful if there was using some kind of material from nature, that we know is very safe, to deliver drugs. Touchingly, Jennie wondered “Can I help the lives of people out there?”

The talk went on to describe the fascinating structure of the outer cell membranes and how they are built with molecules that have one end that is attracted to water and one end that is repelled by water. These align themselves to form a membrane that is two molecules thick, with the water repelling parts of the molecules buried within the wall (see here for nice description). Critically, the cell wall has a number of proteins embedded in its surface. They perform a number of functions, including allowing some molecules to enter the cell.

Jennie went on to describe the “nano-particles” that her research was looking at. These particles are so tiny that, if scaled up to the size of a football, a football would be the size of the earth! Jennie hopes to be able to use these nanoparticles to encase drugs that would not ordinarily be able to survive a trip into the digestive system and allow them to be absorbed by the transporter molecules into the cells and thence into the bloodstream.

A beautiful microscope image was shown of a cell wrapping itself around a nanoparticle, much like ivy wrapping around rock to envelope the particle.

Incidentally, there is a whole area of “Nano Medicine” (see here) and also journals devoted to this topic (e.g. see here)

At this point the reins passed to Eleanor who described the research she was involved in that was looking at targeted therapeutics and also ways of imaging cancerous areas of the body.

When tumours grow rapidly, their blood supply sometimes can’t keep up. This results in the centre of the tumour being starved of oxygen, a state known as hypoxia. Unfortunately, a lack of oxygen significantly degrades the effectiveness of the two main cancer therapies (chemotherapy and radiotherapy).

Work that Eleanor is involved with has resulted in a drug that specifically targets these regions of “hypoxia”

In addition, her research has looked at a technique to finding these areas of hypoxia in the body by MRI (which is relatively common) as opposed to the current technique, PET (which is only available in Manchester and London). Whilst the details of her research remain under wraps until publication of her thesis, it is known that Glucose tagged with radioactive Fluorine18 is taken up by cells but (becaues of the Fluorine) cannot be metabloised and remains trapped in the cell. As cancerous areas take up a lot of glucose, they also take up a lot of the radioactive Fluorine18. Cancerous cells (due to their high rate of cell division) are vulnerable to radiation and are killed by the positron particle released when the radioactive Fluorine decays. You can read more about some work performed on this technique back in 2003 here

Eleanor mentioned, as an aside, that an element called Gadolinium is used as a contrast dye to show up blood vessels during MRI scanning (they are otherwise difficult to see by this technique). NSB, having never heard of Gadolinium before, was convinced that this was a wind up and wondered whether the presenters would try and push their luck by suggesting that the element lay between Gandalfinium and Obiwonkenobium in the Periodic Table.

Upon checking the Internet later, however, it seems that Gandolium is a pukka material (see here) - which just goes to show.

No comments:

Post a Comment