Aspirin: Pharmacokinetics & Pharmacodynamics

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  • 0:04 Aspirin
  • 0:52 Pharmacokinetics
  • 1:57 Pharmacodynamics
  • 4:02 Lesson Summary
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Lesson Transcript
Instructor: Justine Fritzel

Justine has been a Registered Nurse for 10 years and has a Bachelor's of Science in Nursing degree.

Aspirin is a well-established drug with many proven uses. In this lesson, we'll learn about the pharmacokinetics and pharmacodynamics of the drug aspirin.


Aspirin is a medication used for pain, fever, and inflammation. It is also a blood thinner. Besides having these medical uses, it has a variety of non-medical uses. Adding aspirin to a vase of flowers helps the flowers to last longer, or applying a facemask with aspirin in it will help improve your complexion.

Aspirin was discovered in the late 1800s and has been widely used since that time. In the 1950s it was recognized as the world's highest-selling drug. It is so popular that over 3,500 articles are written about aspirin every year. In fact, close to one hundred billion aspirin tablets are produced annually.

Now you probably understand why aspirin is often called a wonder drug. Let's look at how the body processes aspirin next.


Pharmacokinetics is a term that simply describes what the body does to the drug. This includes how the drug is absorbed, distributed, metabolized, and eliminated.

Aspirin is available in oral forms. When taken, it is absorbed in the gastrointestinal tract. It is distributed to all tissues of the body. In pregnant women, it does cross the placenta to the fetus. It is also passed through breastmilk to a nursing infant. In the body, it quickly breaks down into salicylic acid, and the liver changes it into metabolites. It is excreted by the kidneys.

The half-life of aspirin is only 15 to 20 minutes. Half-life is the amount of time it takes to decrease the concentration of the drug in your body by half. Once the aspirin is broken down into salicylic acid, the salicylic acid has a half-life of six hours. In higher doses, the half-life increases, and in toxic doses it may exceed 20 hours.

We now have an understanding of how our body processes aspirin, let's look at how aspirin works on our body to achieve the intended results.


Pharmacodynamics of a drug refers to the action the drug has on our body to elicit the intended effect. Aspirin is effective to reduce inflammation, relieve pain, reduce fever, and thin blood to prevent clots. Aspirin inhibits the action of enzymes in the body to achieve these results.

Aspirin inhibits prostaglandin synthesis, which results in its analgesic effects. Prostaglandins are a substance similar to hormones that affect different body functions. They can cause muscle contraction and blood vessel constriction and dilation. Prostaglandins can increase blood pressure and are a contributing factor to inflammation. Vessel dilation, also called vasodilation, is when the blood vessels stretch to widen the blood vessel. The stretched blood vessel results in decreased blood pressure.

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