On my previous post I mentioned that another topic that got me hooked up was Pharmacology, so today I will give you a small overview of what I studied during those lectures and why I enjoyed it so much. Basically, Pharmacology is the branch of Biology that studies drugs (broadly defined as natural or endogenous molecules) and their effect on living systems.
We started by understanding all the phases and steps that a molecule has to go through before reaching the toxicity tests on lab animals and then we started figuring out all these toxicity tests that will eventually lead to the molecule being sold on a pharmacy shelf. All these regulations and sequential phases made me realise how secure the drugs we can buy are, even though some of them are retired from the markets after many years due to problems that arise on a large scale population, as it is when drugs are commercially available. Eventually this should reassure people with a negative idea about the pharma industry, since even when a drug is on the market, researchers are monitoring potential side effects that did not occur during the many phases of a molecule analysis.
The second part of these Pharmacology lectures where more into the biological side of the question, rather than the theoretical one as the first part of this course, and we started figuring out that Pharmacology is actually composed of two branches: Pharmacokinetics, that studies the effects of a living system on a drug, and Pharmacodynamics, that studies the effect of a drug on a biological system. While it is quite intuitive that a drug has an effect on a biological system, I had never thought that a biological system can actually have effects on drugs. Therefore, when we started studying how a drug can pass through biological membranes and the different ways of drugs administration, I realised that there are so many details to be aware of when introducing a molecule into our bodies. If we are able to take a tablet of ibuprofen when we have headache, it is because people researched on the best way to “pack” this molecule so that we can just ingest it with some water and, despite the fact that it needs to be “digested”, we can have some pain relief after 10 to 30 minutes.
I will not go into details about this branch of the Pharmacology, even though there are so many interesting topics I could go on talking about for hours, and I will move on to the next branch, the Pharmacodynamics: we went right into receptors (proteins that can “sense” the outside word and act accordingly to the conditions of the surrounding environment or other signals, in order to survive and reproduce) and their molecular mechanism after they are activated by an outside stimulus/molecule.
For now, I will just quickly mention these receptors and I promise I will have the chance to be more detailed about them (receptors are the structures that allow neurons to produce electricity and I will definitely spend some time talking about them later on) and for the SFR I would like to talk about Pharmacodynamics, and in particular about the ADME, an acronym that is the basis of Pharmacokinetics and is used to describe the destiny of a drug inside a living organism.
“Science Related Fact” (SRF):
ADME stands for “absorption, distribution, metabolism and excretion” and all the four processes involve drug movements across the membranes. Let’s then unravel each of these words, in order to get an idea of all the work there is behind a tablet you take to feel better when you are ill.
Absorption is the movement of a drug from its site of administration into the blood. Obviously, depending on the drug nature, as well as our body state (like blood flow, stress and so on), its absorption will be different. Just to make an example, aspirin, a very common acidic drug used for pain relief, is better absorbed in the stomach, that is the reason why we take aspirin tablets just by ingesting them with some water and, if we take aspirin after a meal, its action can be noticed much more quickly, due to the acidic gastric environment and to the gastric absorption.
Distribution describes the movement of drugs throughout the body. The distribution of a drug is determined by the blood flow to the tissues, its ability to enter the vasculature system and then to enter the cell if required. This process can be problematic in some cases, as it is the case of delivering drugs to the brains, since the blood-brain barrier, a natural barrier that protects the brain, blocks the delivery of big molecules and drugs with some particular chemical features.
Metabolism is the process of transformation of a drug within the body. Drugs begin to break down as soon as they enter the body and they are made more and more hydrophilic so that they can be excreted out from the body as urine. When a drug is processed during the metabolism phase, it can become pharmacologically inert (meaning it loses its beneficial effect) or, in some cases, its transformation can still be pharmacologically active, or even more active than the drug itself, as it is the case of the anxiolytic benzodiazepines.
Excretion is the removal of the substance from the body, usually via the kidneys in the urine, as I mentioned above, or in the feces. However, drugs can also leave the body via other natural routes such as tears, sweat, breath and saliva. Unless excretion is complete, accumulation of drugs can adversely affect normal metabolism. This might be the case for patients with kidney problems that might have elevated levels of drug in the system and it may be necessary to monitor the dose of the drug appropriately in these patients.