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Introduction to pharmacology

External References
Transcript

Content Reviewers:

Antonia Syrnioti, MD

Pharmacology is the study of medications, or chemical compounds, which interact with various living systems, from tiny molecules to cells, to tissues and whole organisms in order to produce a certain effect.

Every day, more and more new medications are designed to fight diseases, from infections to cancer, heart failure, and depression. But the process of developing a new medication can take a lot of time and money, and it typically consists of three steps. Step 1 is discovery, and that’s when a candidate compound is picked out as a possible therapeutic agent for a specific disease. Step 2 is preclinical research, during which this compound is tested on cell cultures and animals, like mice and rats, mainly to see if it causes any serious harm on living organisms. And, finally, step 3 is clinical development, during which clinical trials are performed. That’s where the compound is tested on humans to see if it’s safe and effective in treating diseases.

For a new medication, clinical trials are done in 4 phases, which can be remembered with the mnemonic “All medications need the SEAL of approval,” which stands for Safety, Efficacy, Approval, and Long term. Phase I trials test the medication in a small group of healthy individuals to see if it’s Safe for humans.

Phase II trials aim to find out more about how Effective the medication is or how well it works at a certain dose. This is done by testing it on a moderately sized group of individuals affected by the condition in question.

In phase III trials, the new medication is compared to the standard treatment to find out if it’s actually just as good as or even better than the existing one. Phase III trials generally involve a much larger number of individuals, and aim to replicate the exact setting in which the medication will be administered in real life, which will then be used as the basis for Approval by regulatory organizations for the market.

This whole process can take up to 10 years or more, depending on the compound. But if all this goes well- congratulations! We’ve got a new medication!

Now, that new medication will have at least three names- a chemical one, describing its chemical structure and used mostly in scientific studies, like N-acetyl-p-aminophenol; a generic name, which is usually a shortened version of the chemical name and is mostly used by health professionals, such as paracetamol or acetaminophen; and one or more brand or trade names, given by the pharmaceutical companies that make the medication, such as Panadol or Tylenol.

Okay, but the journey of drug development hasn’t finished quite yet. Once a medication reaches the marketplace, there’s phase IV, which is a final phase of safety surveillance that looks for Long term or rare side effects that might have been missed. If it’s found to be unsafe, a recall and ban might be needed.

Alright, now, once a medication is administered, it starts interacting with the body. This interaction can be broken down into pharmacokinetics and pharmacodynamics.

Sources
  1. "Katzung & Trevor's Pharmacology Examination and Board Review,12th Edition" McGraw-Hill Education / Medical (2018)
  2. "Rang and Dale's Pharmacology" Elsevier (2019)
  3. "Goodman & Gilman's: The Pharmacological Basis of Therapeutics, 13e" McGraw Hill / Medical (December 5, 2017)
  4. "First Aid for the USMLE Step 1 2020, Thirtieth edition" McGraw-Hill Education (2020)
  5. "Drug interactions: principles and practice" Aust Prescr  (2012)
  6. "Pharmacodynamic Drug-Drug Interactions" Clinical pharmacology and therapeutics (2019)
  7. "When less is more – efficacy with less toxicity at the ED50" Br J Clin Pharmacol (2017)
  8. "The Drug Development Process "  (2021, August 2)