1. Definition of pharmacology and the related subjects. Drug development

Last updated on January 20, 2019 at 11:18

Pharmacology is both a subject and a science. Pharmacology deals with drugs, in particular with their:

  • History
  • Source
  • Physical and chemical properties
  • Biochemical and physiological effects
  • Mechanisms of action
  • Fate in the body
  • Therapeutic, diagnostic and preventive uses
  • Side effects, toxic effects and contraindications

Pharmacology has a handful of “sister”-subjects, that are closely related to it.

Pharmacokinetics deal with what the body does to the drug, as soon as the drug is administered to the patient. This means especially the drug absorption by the body, the distribution of the drug in the body, how the body metabolizes the drug, and how the body eventually excretes it.

Pharmacodynamics deal with what the drug does to the body. Specifically, whether the drug activates, stimulates or inhibits certain mechanisms.

Pharmacotherapy deals with using drugs to prevent and treat diseases, which is what physicians mostly do.

Other, less relevant subjects include homeopathy (complete bullshit), phytotherapy (using plants or plant extracts), toxicology (drug poisoning), pharmaceutical chemistry (production of drugs) and pharmacy (preparation, dispensing, quality control and teaching patients about drugs).

Drug development

How do scientists get ideas for new drugs? In some cases (like opium), they can look to substances that have been used naturally for a long time and use or modify them to suit other needs. However, in most cases, drug development begins by systematically searching for a new molecule that has certain effects. Drug developers can look to already existing drugs and try to modify them to create a new drug with similar, but better effects, or they can try to make molecules that resemble endogenous compounds.

Drugs go through many tests from the time they are first synthesized until they are given to patients. They must be first tested on animals, then tested to see if they are safe for humans, then tested to see if the drug actually has the expected therapeutic effects on humans.

However, these tests are not perfect. It’s impossible to test for all possible side-effects and contraindications, and it’s impossible to know a drugs long-term effect until the drug has been given to patients long-term. The classical example of this is the story of thalidomide.

When a new drug is synthesized, it must first undergo preclinical trials, where the drug is tested on animals for any toxic or unwanted effects.

Then, the drug will begin clinical trials, beginning with phase Ia. Phase Ia clinical trials test the effect of the drug on healthy male volunteers when given in a single dose, to test the acute tolerance of the drug. The reason male volunteers are used is because exposing females to potentially dangerous drugs might negatively affect their eggs. Males produce sperm continuously and therefore don’t have this problem.

Following this, the drug will enter phase Ib where the drug is given in repeated doses, to test the chronic, long-term tolerance.

If the drug passes phase I, it will enter phase II, where there will be pharmacodynamic and pharmacokinetic studies on patients taking the drug over a period of time.

Phase III studies tries to determine the therapeutic effect of the drug in a larger-scale placebo-controlled double-blind study, where half of the patient group is given a placebo drug (a drug that intentionally does nothing, often a sugar pill) and the other half is given the drug in question. Scientists can then compare the results of the two groups to determine the effects of the drug.

If the drug passes phase III trials, it will be commercially available. Later, phase IV studies will be performed, to continue to evaluate the efficacy and safety of the drug.


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4 thoughts on “1. Definition of pharmacology and the related subjects. Drug development”

  1. Phase 1a is given to healthy MALE volunteers. The examiners like to ask the reason for this, which is that females carry all of their eggs from birth, and can’t be exposed to new and possibly damaging drugs whereas males have continous sperm production. You’re welcome 🙂

  2. Hi
    I think there is sth wrong with flashcards of pharma 1.
    Did you delete them or set them as private ?
    Could you pls share them again?
    Thank you very much 😀

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