Introduction to Pharmacology

Pharmacology is a very big field of study of medicine, this will be an introduction in which you learn basic fundamentals concepts essential to learn pharmacology. in future, I will be writing more articles to discuss various advance topics in pharmacology.

What is Pharmacology

What is Pharmacology? Before you start studying you must ask yourself what exactly is Pharmacology? let me explain you in simplify way, whenever you consume Drugs or Medicines, there always going to be some effects on your body, some will be positive & some will be negative. Now how can you predict weather Drugs have positive or negative effects, by understanding it’s mechanism of action. every Drugs or Medicine has its own Mechanism of action & with understanding of it you can predict & understand it’s effects. That’s when Pharmacology study came into action.

“Pharmacology is the science that deals with the study of drugs and their interaction with the living systems.”

Whatever events happens inside our body after consuming drugs are studied in scientific way, that’s exactly what pharmacology is. It includes studying of Medicinal properties of Drugs or chemical compounds, it’s side effects, mechanism of action, metabolism, distribution, excretion & how it interacts with Tissues, cells, organs & etc these nuances are studied under Pharmacology field.

Branches of Pharmacology

Pharmacology is a large field of Medicine with various sub branches & here are some important branches, Pharmacokinetics, Pharmacodynamics, Pharmacogenetics, Pharmacogenomics etc. Among all these branches there are 2 most important ones & those are Pharmacokinetics & Pharmacodynamics. Pharmacodynamics is study of biochemical effects of drugs on the body & it’s mechanism. Pharmacokinetics is the study of Drug Absorption, Distribution, Metabolism & excretion. in simple language, What Drugs does to body is Pharmacodynamics & what Body does to Drugs is studied in Pharmacokinetics.

Each & every branch of pharmacology is important in it’s own way. for example: Pharmacogenetics deals with the genetic aspects in Drug-Body Interactions because drug effects are slightly varying according to DNA make-up of an individuals. There is Pharmacogenomics, which involves genomic technology like the Recombinant DNA technology for new drugs discovery. which basically means there is lot of DNA editing like, cutting, joining from one species to another and all other cool stuff is involved. Examples are Growth Hormones, Interferons & Vaccines like the latest mRNA ones. Chemotherapy is widely used these days especially in cancer treatment. Chemotherapy involves treatment of disease by chemicals that kills cells. funny part is it doesn’t say which cells, whether human cells or bacterial cells. all that matters is killing cells by chemicals. chemicals means drugs or medicines. examples of chemotherapy are Antibiotics, antibacterial, antineoplastics (a.k.a anti-cancer) etc.

Each & every branch of pharmacology deserves a separate long video to explain in detail, subscribe to my Channel so that you won’t miss out lecture video when upload it in future.


Now let’s understand the meaning of Drugs. In modern field of medicine, we use drugs for literally everything, from simple pain management to brain enhancing drugs but those are topics for another video. In Pharmacology, we use drugs for treatment, cure, prevention, diagnosis of disease & to enhance physical or mental wellbeing.

so, what is a Drug? in simple language, it is any substance that produce biological effect when consumed & here is a proper definition of drug, “A Drug is any substance or product that is used or intended to be used to modify or explore physiological systems or pathological states for benefit of the recipient”.

Drugs vs Medicine

before we move forward let’s understand the difference between a medicine & drugs because lot of students in medicine get confused between drugs & medicine. to understand the difference between drugs & medicine you have to look at perspective. There are 2 perspectives, one is scientific & other is legal perspective.

From legal perspective, A Medicine is substance with legal status & it’s used for its medicinal & healing properties. whereas a Drug is substance with illegal status & it is considered as harmful.

but from a scientific perspective, there is no difference between drugs & medicines. they both are same, only words are different but they convey the same meaning.

So, it depends on your perspective & context of your conversations. so whenever i used word Drug i mean from it from scientific perspective.

Sources of Drugs

We know what drugs are & it’s uses. Now let’s explore the sources of drugs. in modern medicine there are many sources of drugs but everything boils down to these 3 sources; Natural, Synthetic & Plant Products Sources.

Natural Sources

Natural Sources which includes drugs that are obtained from Plants, animals, minerals & other natural sources. example: Opium, Cod liver oil, Caffeine and etc.

Synthetic Sources

Synthetic Sources which includes drugs that are made using chemical synthesis in lab example: quinolines, sulfonamides, & neostigmine etc.

Plant Based Sources

Plant Based Sources includes drugs that are obtained from plant constituents. example: Alkaloids, Glycosides, Oils, Tannins, Resins etc.

Now you might wonder why Natural & Plant sources are categories separate because Plants came from nature a.k.a Natural. but Plant & Natural Sources are not the same. There is a slight difference & the only difference is Plant Products Sources contains a group of biochemicals which are produced in parts of plants such as Alkaloids, Glycosides & oils. These are basically a group of biochemicals found in plants. Natural Sources contains drugs which are obtained from various natural resources such opium from opium plant, Cod Liver oil from Cod Fish & Penicillin from Penicillium Fungus. These are various natural sources.

Routes of Administration

Now let’s understand various routes of drug administration but first you have to understand what drug administration means? drug administration simply means it’s an act of giving treatment. There are various methods of drug administration but fundamentally there are only 3 routes of drug administration. Oral Route, Parenteral & Topical.

Oral Route

Oral Route involves consuming medicines via mouth. example: pills, syrup, tablets. this is most common route of drug administration.

Parenteral Route

Parenteral route involves giving drugs directly into systemic circulation or blood stream. example injections, inhalation, transdermal & transmucosal etc.

Topical Route

Topical Route means we apply medication directly on skin or outer surface of skin & the main drug is absorbed into body to reach systemic circulation. rate of drug absorption at site is an important factor in topical route.

Each & every routes of drug administration has it’s own advantages & disadvantages.