The Half Decent Pharmaceutical Chemistry Blog

The fact that this blog will close in July is putting me in the situation of having to find good pretexts to talk about all those remaining themes I had planned to discuss here, before I definitely leave the world of pharmaceutical sciences.

Surprisingly, one of these inputs was provided by a person who is, and will always be, one of my most hated individuals in the world: my pathology professor. If you remember, I already told you the story of when she called me out of the room the exam was taking place to tell me, vies a vies, I had an arrogant behaviour, that would have caused me disappointment in my life.
Well, you can imagine my reaction when I saw the following scene: she was trying to go out of the department in her car, presumably in a hurry, under heavy rain, but the only way out was closed by a parked car.

She then started to attract a lot of attention from everyone working in the buildings nearby by savagely and angrily blowing the horn and (but I’m guessing here) shouting and cursing and sweating and assuming some pricelessly infuriated expression.

This memorable scene went on for more than 15 minutes until she got the car removed and drove away. In the meantime, I was setting up a RT-PCR and only towards the end realised not only what was going on, but also who actually was sitting in that blocked car. So, I apologize for the poor quality of the photograph (taken with a mobile phone): with hindsight, I would have recorded the whole scene and put it on YouTube (and then posted it here).

Anyhow, the most important thing I could make out of this satisfactory moment is that it serves the right introduction to talk about intra-arterial chemoembolization.
Targeting is obviously something of paramount importance for any drug, not to mention those with a low therapeutic index. One of the parameters one could try to adjust when the only reliable pharmacological solution is poorly selective is positioning. Generally speaking, this can be direct, passive, physical (endogenous or heterogeneous) or active.

Chemoembolization (which is an example of direct localisation) isn’t probably the wittiest but I’ve always found the idea behind it simply brilliant. In a few words, a drug is introduced, as micro-spheres, directly into an artery that leads to the target.

As the name implies, this approach combines intra-arteriolar chemotherapy with embolization: the latter, a less immediate to understand concept, involves the induction of an occluding thrombus in order to prevent further blood supply to a tissue, such as a solid tumour.

The techniques is based on 0.2-0.6 mm diameter micro-spheres to deliver the drug: this particular delivery system is employed because of its size, which is just what it takes to block an arteriole. This results not only in massively accurate targeting, as the drug is released right where it must operate, but the effect is associated with a progressive block in the vascularization of the tumour.