Question: What chemistry goes into making the actual drug molecule? :) (you promised that it would be interesting ;))

Emily Bullen answered on 14 Mar 2012:

Ok, here goes… (sorry it’s been so long, I wasn’t in my office yesterday!)
Well, I’m not exactly going to talk about chemistry, as I don’t know very much about it. In my world the chemists will be the ones understanding exactly which reaction we want to happen, and which ones will also happen that we can’t avoid.

When the chemist finds out what molecule he/she (I’m going to stick to he for practical reasons, but there are lots of female chemists!) needs to work out how to make it. That’ll be by making parts of the molecule separately, and then putting them together, like building blocks really. Each of those building blocks takes quite a bit of effort to do, they involve:
– adding all the ingredients (solid stuff, solvents, sometimes gas)
– getting the conditions right for the reaction (the right temperature, and the right amount of mixing)
– separating the molecule we want from those we don’t want (there are a few ways of doing this, again, if you are interested just ask but I won’t go into too much detail otherwise I’ll be writing a book!)
– taking the molecule we want from being dissolved in the solvent, to being a solid (by crystallisation, as I explained in your question about crystallisation)

What do I do? I make sure that all of those bits will work in a 2000L pot rather than 0.2L. I need to check the properties of all the chemicals used, to check they aren’t going to explode (yes, it could happen), and check they won’t eat through the pipes.
A big bit of my job is also checking whether it will mix ok, and making sure that the crystals we make are the right size and the right “form” (the form is how the molecules are arranged. Did you know that coal and diamonds are made of the same molecules, just arranged differently??)
A good example is a cake. Baking 1 cake in your kitchen might be pretty simple, but what if you wanted to bake cakes for 500 people?? It would take forever to do 1 cake after the other, so you might want to make one huge set of batter… but it would be much harder to mix together and get smooth. Then when you bake it, do you bake 1 big cake, or lots of normal sized cakes? depending on the size of the cake you will need to cook for different amounts of time.

I’ll stop there, that was a small bit of explanation, what did you think? Did it make sense? are you bored silly? Be honest…