Basics of Pharmacology pt.2

What are pharmacokinetics?

what the body does to the drug (how it processes it)

What are the different phases of pharmacokinetics?

absorption, distribution, metabolism, and excretion

Absorption is.....

how drugs are introduced into the body

-ex. melting on tongue, rubbing something on your arm, etc.

Absorption is impacted by....

route of administration

What is the safest and slowest route of administration?

oral

What is the fastest but most high risk route of administration?

vascular (IV)

Is oral or vascular administration more expensive?

vascular

What is distribution?

the movement, and how it moves through the body

Distribution depends upon what three things?

perfusion of tissue, lipid soluble, and protein binding

What is perfusion of tissue? and does poor perfusion of tissue look like in someone?

-the process of fluid through the circulatory system to an organ or a tissue

-someone with poor vascular perfusion will not get the drugs as fast as needed

What is protein binding?

how tight it binds to protein

-ex. a drug that is carried through the blood by attaching to proteins

What happens if a drug is attaches strongly or loosely to a protein?

-if a drug is attached strongly it will leave the body slower than a loosely attached drug that will leave the body faster

When thinking of metabolism think of......

"Packing Up"

What is the organ that is responsible for metabolism? and what happens if this organ isn't working properly?

-the liver

-if the liver is not working properly you have a risk for toxicity

What is the first pass effect?

a part of the drug goes to the liver and loses some of it and it's effective amount

The first pass effect only happens with which kind of drugs?

oral drugs

The first pass effect happens before what?

happens before it is distributed (what's being distributed is a fraction of what the patient took)

Because of the first pass effect what needs to be done with oral drugs?

oral drugs need to have a higher concentration

Think of the P450 system as the...

detox team

What is the P450 system?

a group of proteins in the liver that help to detox and "package" the meds (breakdown)

What does P450 system do?

either takes the drug and makes it more useable or takes it and breaks it down (if it takes it and breaks it down, it is trying to make it leave the body faster)

What can activate the P450 system?

grapefruit (can make the system become less sensitive to the drug that is taken with it, which can be dangerous)

How can polarization be used for metabolism?

liver can alter the drugs polarization to make it more polar to be safer to be excreted

The more polar the compound the easier it is to leave what?

the kidneys

What is a good way to remember how polarization works?

imagine you are at the post office and they are saying that you can't sent a package because it needs more bubble wrap (bubble wrap being polar)

What is something important to check with the liver and why?

-AST/ALTs

-if someone's liver enzymes are off they might be at risk of toxicity to drugs

What is also important to remember with multiple drugs being taken during metabolism?

the liver could be overworked with multiple medications, that they might be competing for the livers attention, which could then cause a med to be toxic

What organ is responsible for excretion? and what can happen if there is something wrong with this organ?

-the kidneys

-if something is wrong with the kidneys you are not excreting the drugs properly, putting you at risk for toxicity

What is a half life?

helps determine the timing of the drug and how much of the drug is needed to take to stay in the body

Are shorter or longer half lives excreted faster or slower?

-shorter half lives are excreted faster

-longer half lives stay in the body longer

ex. the half life of lasix is 2 hours. You administer it at 8AM. How much will be present in the body by 8PM?

0.3

What does onset of a drug mean?

when we start seeing the drug take effect

What is the peak of a drug?

when the drug is the most therapeutic

What is the duration of action of a drug?

how long the drug is therapeutic for

-ex. the length of time you will see controlled blood pressure

What is the trough of a drug?

the point when the drug is the lowest in the body

What is critical concentration?

amount of drug that is necessary to be effective

-"two tablets twice a day is needed to maintain critical concentration" how it sounds in a sentence

What is a loading dose?

some medications need a boost, so a higher dose is given at first and then a lower dose (the lower dose maintains it)

What are the factors affecting the body's response to a drug? (7)

age, weight, gender, tolerance, interaction, pathophysiology, and pharmacogenomics

How can age affect the body's response to a drug?

in younger or older populations kidneys might not work as well so dosage would need to be lesser

How can pathophysiology affect the body's response to a drug?

the disease might have affected other organs of the body that might have different responses to certain drugs

How can pharmacogenomics affect the body's response to a drug?

someone's genetics can determine what meds are effective and are better for treatment

What are contraindications?

people with certain conditions or symptoms can make it unsafe to receive a drug