Module 3 Flashcards
Ch. 4,5
what is absorption
movement of a substance from administration site across body membranes, to circulating fluids
what is dissolution
how quickly a drug disintegrates and disperses into simpler form- which makes it more bioavilable
distribution
the process of transporting drugs through the body after they have been absorbed or injected
excretion
removing drugs from the body
metabolism
process of chemically converting a drug to a form that is usually more easily removed from the body
pharmacogenomics
study of genetic variations that influence an individual’s response to drug therapy
pharmacokinetics
study of drug movement throughout the body, how a body handles medications
why do nurses care about pharmacokinetics?
we need to know how a drug is supposed to act and what it looks like if a drug is working or not. it is important to know how fast a drug can get absorbed, how it gets distributed in the body etc.
What are some barriers that medications face as they pass through our systems? These barriers can impact how much of the drug actually works in our bodies.
- Acid, digestive enzymes, in the stomach and liver
- Blood- brain barrier
- Proteins- some drugs are protein binding
- Membranes (that coat linings in our bodies) Ex) intestines
what are the 4 pharmacokinetics processes
absorption, distribution, metabolism, excretion
Name two ways that drugs pass through membranes in the body and describe, in your own words, what they mean.
- Active transport: energy is required for this drug to get through the membrane
- Diffusion or passive transport: does not need energy, but chemical (drug) moves down the concentration gradient
Drugs that are lipid soluble pass through membranes in the body more easily than drugs that are not lipid soluble. What is the reason for this?
It is more likely to get through the barrier. The head is hydrophilic which means it likes fat- therefore fat is easy to get through this layer. Water is much harder to pass through this layer because again, fat and water don’t like each other.
Small molecules such as urea and alcohol can pass easily through pores in the plasma membrane, and large molecules do not pass easily through those same membranes. What is another way for those large molecules to influence those target cells?
They can bind to receptors on the outside of the cell membrane which activates second messengers which can produce a change.
What is the primary pharmacokinetic factor that determines the length of time it takes a drug to produce an effect? Why do you think this is?
ABSORPTION! if we don’t absorb it, there won’t be any impact in the body
Ex) transdermal patch over a scar= won’t absorb
There are numerous factors that affect absorption. What are those factors?
drug formulation, dose, route of administration, size of drug molecule, surface area of the absorptive site, digestive motility, blood flow, lipid solubility of drug, ionization, pH
explain how drug formulation affects absorption
the form of the drug helps determine how quickly it is absorbed. liquids (orally) are absorbed much faster than tablets
explain how dosage affects absorption
a higher dose of a drug is absorbed faster
explain how route of administration affects absorption
IV administrations are much faster absorbed
explain how size of drug molecule affects absorption
Size of drug molecule: larger drug molecules take longer to absorb than smaller ones
explain how the surface area affects absorption
the larger surface area, the faster absorption
explain how digestive motility affects absorption
changes in GI motility (capability of motion) can speed up or slow down absorption.
Ex) when you have diarrhea or take a laxative, your intestinal motility speeds up very quickly. If you have a drug in there, it won’t get absorbed as much because it is going through your system so fast- doesn’t have time to absorb
explain how blood flow affects absorption
greater blood flow to the site allows for faster absorption. you need blood flow for something to get absorbed
explain how lipid solubility of drug affects absorption
lipid-soluble drugs are absorbed faster than water-soluble drugs
explain how pH affects absorption
how acidic of basic it is
what does ionization mean
It gains a charge. It either gets an electron or releases an electron. You take an aspirin and goes into the stomach. It gains a charge because it is in an acidic environment, and it doesn’t get absorbed because it is now ionized. The enteric coat prevents it from dissolving in the stomach and allows it to dissolve in the intestine- there isn’t any acid in the intestine.
How can PH levels impact the ionization of a medication?
Briefly explain what happens to aspirin when it leaves the acidic environment of the stomach and enters the alkaline environment of the small intestine.
It impacts the absorption.
The aspirin becomes ionized in the digestive tract. In an ionized form, it is not as likely to be absorbed and distributed to cells
how can drugs impact the absorption of a medication?
some block absorption. Ex) tetracycline, when it is taken with calcium or magnesium the tetracycline does not get absorbed because it interacts with magnesium and calcium. (Mg, Ca can significantly delay the absorption of a drug, so you should not give tetracycline with calcium or magnesium supplements
how can food impact the absorption of a medication?
high fatty foods delay the emptying of your stomach
how can your stomach impact the absorption of a medication?
depending if it is full or empty could delay the absorption of a drug or medication
Why would a patient who takes a laxative impact the absorption of another drug?
If meds pass through fast, they don’t have time to absorb.
Explain the pathway for the distribution of medication.
IV drugs goes right into the blood, inhaled drugs go right to the lungs
What elements impact the body’s ability to transport medication around the body?
BLOOD FLOW!
Some places in the body can hold onto drugs. What are some of those places? What is an example of a medication that would build up in your teeth?
skin, bone, adipose tissue, teeth
ex) tetracycline is an antibiotic that could build up in teeth. it should never be given to children because of how they are growing and their bones. If it gets in there system, it can cause teeth to be gray or discolored.
Ex) Anesthesia- obese people hold on to the gas longer because the adipose tissue absorbs it