How (Medicinal) Drugs Work

Sep 17, 2020
By Peter Buttery 

Have you ever wondered how one small pill can relieve a headache or cure a disease? The answer is not magic, its pharmaceutical chemistry! Most medicinal drugs contain chemical substances that cause your body to undergo a physiological change to fix or otherwise alleviate a problem in your body that was causing the discomfort.

  Taking a look inside a medicine cabinet or pharmacy reveals many different types of drugs that can help to resolve many kinds of problems. Broadly speaking, some of these drugs work by targeting problems within your own body and some work by targeting bacterial or viral invaders that are causing an infection.

A look inside an Ibuprofen tablet (Image source)


   Drugs that target your own body seek to resolve a problem caused by your body functioning incorrectly. These problems can be as simple as an annoying headache that you want to get rid of or as complex as cancer, where your cells uncontrollably divide. Drugs often target proteins like enzymes that perform chemical reactions in your cells. If these enzymes are not working correctly, you may need to either turn them on or stop them. For example, the pain reliever Ibuprofen works by blocking the function of enzymes called COX enzymes, which create substances in your body that mediate pain, inflammation, and fever.

Many drugs work by preventing the conversion of substrates into products by enzymes. (Image source)

   Other drugs target pathogens that invade your body and cause an infection, like strep throat, chicken pox, or malaria. These drugs work by targeting the tricks and tools used by the invading pathogen that are not present in the healthy human body. If you remember how plant and bacterial cells have cell walls while animal cells do not, you’re on your way to knowing how penicillin works! The antibiotic penicillin inhibits (blocks) an enzyme involved in the synthesis of the bacterial cell wall, which stops the bacteria from growing and means bacterial cells are killed while your body’s cells remain happy and healthy.

Willow tree bark was a popular early medicine (Image source)

  So I said that the pills you take contain “chemicals”, but what are they exactly, and where do they come from? Many of the first medicinal drugs ever discovered came from plants and other natural sources. For example, it has been documented that the ancient Sumerians and Egyptians knew that willow bark was a good treatment for headaches. We now know that willow bark contains a compound that serves as a molecular building block to modern aspirin. Furthermore, perhaps the most influential medicinal drug to date, penicillin, was famously discovered by Sir Alexander Fleming by accident!  Fleming came to his lab one day to see a mold growing in one of his bacterial samples that appeared to kill the surrounding bacteria. Later on, other teams of researchers investigated Fleming’s observations and showed how the mold made a chemical substance called penicillin that could fight bacterial infections.

The mold identified by Sir Alexander Fleming which produces the drug penicillin. (Image source)

   Modern drug production involves a slightly more refined process, but in many cases natural products can still be part of the final drug. Both the willow bark and the mold were later determined to have a single active substance that produces the desired effects. An exciting field of study called drug discovery involves identifying new natural or synthetic chemical substances that produce a desired effect to cure a problem of interest. As the field of drug discovery progresses, scientists hope to one day be able to beat even the toughest diseases like cancer and Alzheimer’s disease.

Edited by Lillian Lowrey and Brandon Le