Factors Influencing Medication Action & Effectiveness

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  • 0:00 Factors Influencing…
  • 1:09 Age & Hydration
  • 2:48 Pregnancy, Other Drugs, Route
  • 4:03 Lesson Summary
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Lesson Transcript
Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

This lesson will give you an understanding of the fact that doctors and nurses must take many important factors into account when giving a person a drug.

Factors Influencing Drug Action

When a doctor prescribes you a pill or injects you with a medication in the hospital, it may seem like a really simple thing to an outsider. It doesn't seem like there's much to it at all, and it seems like anyone can figure out what pill to give and when. Some people may realize that there is more to this, however. For example, you may know that the amount of a drug that is to be given is partially based on the person's weight, but that is also very superficial view of things. That's because there are literally dozens of factors that influence a medication's action and effectiveness on and within the body. All of these need to be taken into account, or a person may suffer serious consequences. This is why doctors exist, and this is precisely why a person with no medical training cannot safely figure out what drug to use and when. We can't possibly cover all of the factors in this lesson, because they range from sunlight and barometric pressure, to the way a person's psychological status influences a drug within the body. However, we will go over some of these factors so that you can gain a good appreciation of their overall importance.

Age & Hydration

Let's get started with factors like age and hydration status, the state of a person's level of fluid in the body, be it too little, too much, or normal. When a drug is given to a neonate, a newborn, their special circumstances have to be taken into account. Compared to an adult, a neonate has an underdeveloped gastro-intestinal, or digestive, system as well as inadequate renal, or kidney function. This means drugs should be chosen with care, so they don't compromise the entire body because of these underdeveloped systems. On the complete opposite end, older adults have their own concerns. These may include inappropriate renal function as well as decreased hepatic, or liver function. This means that the drugs that are given to them have to either a) minimally affect these organ systems to begin with, or b) be adjusted by dosage so as not to cause undue harm when compared to a healthy young adult.

As I recently said, a person's hydration status must also be considered. If a person is edematous, a state characterized by excess fluid in the tissues, the amount of a drug they need to be given is, all else equal, larger than the amount that would need to be given to a person who is not edematous. This is because the drug has to be distributed over a large volume of bodily fluids. On the flip side, a person who is dehydrated will require a smaller dosage of the drug in order to produce the desired drug action when compared to an edematous person or an otherwise completely healthy adult who is not dehydrated.

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