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!

The Umbrella Syndrome

We are still in the midst of a scorching summer. But rains are not far away. Once the rains arrive, umbrellas will be everywhere. And with umbrellas on the scene, we will start hearing a strange complaint - ‘whenever I step out of my house without my umbrella, it invariably rains’. I call this the ‘Umbrella Syndrome’.

Do you believe in the Umbrella Syndrome or have met someone who does? Prima facie, it seems unlikely that the whole climatic system is conspiring against a lowly human being, keeping the clouds at bay so that he forgets his umbrella, and then suddenly coming down on him with full force, sending the poor fellow scurrying for shelter. Yet it seems to happen more often than not, at least to us.

I think I have a theory about why it happens. The explanation is based on two principles taken from two related fields - neuroscience and cognitive psychology. The names may sound weighty, but the principles are simple.

The principle from neuroscience is about how memories are formed. It is well known that our brain is a giant network of cells called neurons. Neurons derive their power from their connections. A neuron is on an average connected to 10,000 other neurons. The place where a connection between two neurons is made is called a synapse. This is where the outgoing link from one neuron meets the incoming receptacle of another neuron.

The of the most accepted theory is that memories are formed by strengthening of the synapses. Scientists like Nobel Prize winner Dr. Eric Kandel have studied this mechanism in depth. The details of the mechanism might be too complex for us to cover here, but there is one aspects that takes us closer to understanding the Umbrella Syndrome - synapses are strengthened more frequently under emotional circumstances, especially in painful situations. This is why people caught in accidents seem to remember even small details of that unfortunate incident even years later.

This then maybe the first hint of an explanation. Being caught in heavy rains without an umbrella is no doubt a painful situation. It is likely that our brain stores it more frequently than those incidences when we are not caught in this appalling situation.

Here spurs the second principle in action, this time coming in from cognitive psychology. This principle is called the availability heuristics, a part of a wider principle called heuristic bias. We are grateful to the scientists Amos Tversky and Nobel Prize winner Daniel Kahenman for this theory. In short, the availability heuristics means that if an event can be brought to mind easily and vividly, the mind overestimates its probability. The word heuristics here means a back of the envelope calculation, a quick guess. This is regular business for the mind, this is the way it has learned to work. It cannot wait for conclusive evidence to be collected. If there is a rustling sound in the bushes, the mind makes a quick guess that it’s a predator, and prompts us to run. If it had waited till more information is available, most of our ancestors would have been lunch and dinner in the wild.

Coming back to umbrellas, we can now see how it might be happening. The incidences when we forget the umbrella AND get drenched are painful, and are easily and vividly remembered. Working with availability heuristics, mind then calculates the probability of this incidence much higher than what it actually should be. Translated into everyday terms, it always seem to rain when I forget my umbrella.

At the toll nakas, the other lines always seem to be going faster, what do you think?