Awareness series - How Medicines Work

Medicines are an integral part of our lives. Most of us regularly take medicines for various reasons. Do you ever wonder how they work?

In this article I will try and explain the mechanism of drugs. The information is really basic, so those of you who know even a little bit about medicines should sign off now. Another point, the information is about the Western, or allopathic medicines.

Learning number one – almost everything in our body is the work of proteins. Proteins not only make the body but also run it. Protein are the material of which the cells are made. They make the muscles move, they make enzymes like insulin, which are proteins themselves. They are the reason why we don’t develop disease and they are reason why we develop disease. So let’s learn a little about proteins.

Learning number two – almost all of these wondrous powers of proteins are due to their shape.

Shown in the picture is the familiar hemoglobin – a protein. (To be exact, it’s a sub-part of the whole hemoglobin molecule, but it’s ok for our purpose.) You can easily see that it has a complex shape. Actually, it’s a long chain of smaller molecules called amino acids. The chain twists and turns, giving proteins their distinctive shape. The chain seen here has about 140 smaller amino acid molecules.

Learning number three – if we can change the way a particular protein works, we can create some effect on our body. Remember that the effect can be both good or bad. The simplest way to change a protein’s function is to send a molecule that will attach to the protein. But how will a strange molecule attach to a protein?

In their complex shape, proteins harbor what are called as ‘active sites’. These are small sections of the chains where other molecules can attach, or ‘bind’. In fact, proteins have an affinity, or liking for certain types of molecules.

Learning number four – the medicine we take contain such molecules. They are called ‘ligands’ in the language of the pharma people.

Let’s try and put things together now.

When we take a medicine, the ligand molecules go and bind to some protein molecules in certain cells. The effect of this binding is to change the function of the protein in such a way as to have a curative effect on our body.

An an example, take paracetamol. It binds to a protein called COX. Now this COX is a special type of protein called enzyme, which is responsible for making us feel pain. Though the whole scheme is pretty complex, in simple terms the paracetamol molecule inhibits the action of COX. This increases the limit at which we feel pain, making the pain of minor aches go away.

Now, the question we all have- how does the medicine ‘understand’ where to go? The straight answer is that it does not. The drug molecules are carried everywhere in the body, but they only bind to the protein they are supposed to. In this process, some other proteins in our body play an important role. They are called ‘receptors’, ‘transporters’ and ‘carriers’, but we can skip those details for now.

I know that another question is by now popping up in your mind. What if the the medicine molecule binds to some other protein as well? It can, and it is called a ‘side effect’ of the medicine. When a new medicine is being developed, it has to be ensured that the side effects are detected and kept within acceptable limits.

I am sure you are already thinking – what about the anti-biotics, which kill bacteria? They don’t work on our proteins, right? Well, I hope you have not forgotten – bacteria are also living organisms, and so are all made up of proteins!