This study focuses on what the body does to drugs after they are administered.
What are the four stages of pharmokinetics?
Absorption, distribution, metabolism, excretion
High to low concentration
Moves along the concentration gradient utilizing a carrier protein. Does not use energy
Movement against a gradient and requires energy.
stage of pharmacokinetics that involves movement of the drug form the site of administration to the bloodstream
For a factor affecting absorption, the higher the dose, the __ concentration gradient for diffusion? (pg 44)
For oral meds, most absorption occurs where?
in the small intestine
What do high fat foods do to med absorption?
they slow the process down
How does blood flow affect absorption?
Areas of high blood flow (large muscles) that have a high blood supply will have faster absorption and vice versa
Acids are absorbed in __ because they are nonionized
Acids. Ex) asprin absorbed in the stomach (acidic environment)
Bases are absorbed in __ because they are nonionized.
Bases. Drugs that are weakly basic are better absorbed in alkaline environments such as the sm intestine.
the greater the surface area, the __absorbtion will be.
Faster. ex) lungs, sm intestine.
The second stage of pharmokinetics that transports drugs throughout the body via blood stream
organs such as the heart, liver, kidneys have a higher exposure to a distributed drug because why?
They have a greater blood supply.
__ soluble medications can cross barriers such as the blood/brain barrier wich make them have a wider dristribution.
tissues such as eyes, bone marrow, teeth and adipose tissue can store __ amounts of protein affecting distribution.
Drugs often bind to protein and form drug-protein complexes making them not able to cross cappillary membranes (trapped. only __ drugs will reach target cells?
Drugs often __ with one another for protein sites causing intercations affecting distribution.
Drugs compete for protein sites with other drugs that can cause displacement. Why is this dangerous?
Displaced meds can reach high levels of free medicatino which can cause adverse effects.
The blood brain barrier affects distribution because drugs cannot pass through it with the exception of what kinkd of drugs?
What can inflammation do to permeability?
3rd process of of pharmokinetics that the body uses to chemically change a drug molecule also called biotransformation.
Where is the primary site for durg metabolism
Chemical changes always result in what?
Changes in the drug structure allow for what?
allow for excretion. Lipid sluble to water soluble
What are the products of drug metabolism?
Metabolites. Usually less active than the original molecule but they may be more toxic. ex) Tylenols metabolite is highly toxic to the liver.
Medications that have no pharmacologic activity until they undergo metabolism.
Metabolism takes place in the liver throught hte the hepatic microsomal system aslo known as?
P-450 system. Its has more than 50 CYPs (enzymes that metabolizes drugs. Different CYPs are called isozymes.
Not only do CYPs determine the speed at which a drug is metabolized, they also contribute largely to what?
Besides the liver, where also can drug metabolism occur?
the kidneys and small intestine.
Drugs metabolized by a CYP enzyme.
A drug that inhibits or stops the action of the CYP isozymes which increases toxicicity. Can contribute to toxic drug levels.
Drugs that accelerates metabolism of specific isozymes. These may cause drug level to drcrease more rapidly.
Inducers. With these you may need higher dosages for a theraputic effect.
Drugs absorbed after oral administration cross directly into the hepatic- portal circulation which carries blood to the liver before it is distributed to the to other body tissues. What is this called.?
The first pass effect.
Why do drugs need with a high first pass effect need to be administered by another route other than oral to be effective?
because some drugs get completely metabolized which losing their effectiveness.
In older people Enzyme activity is often __?
With liver impairment, a person will have decreased __?