Pharm Principles (325E1) Flashcards
3 phases of drug action
every drug every time
1: pharmaceutic (only for oral)
2: pharmacokinetic (iv drugs enter here)
3: pharmacodynamic
Phases of drug action: pharmaceutic (1)
drug dissolves to be used and absorbed in blood and body (dissolution) all oral drugs and only occurs w/ oral drugs
Phases of drug action: pharmacokinetic (2)
drug moving through the body and what the body does to the body (4 processes: absorption, distribution, metabolism, excretion)
Phases of drug action: pharmacodynamic
what the drug does to the body (MOA, intended effect, therapeutic action)
pharmacokinetic (2): absorption
the drug goes into the small intestines and then into the blood
pharmacokinetic (2): distribution
drug has already been absorbed into the blood and now it leaves the blood stream and goes to the site of action and exerts it effort
pharmacokinetic (2): metabolism / biotransformation
after the drug has been excreted, it is broken down by liver to go from lipid soluble to water soluble so it can be removed from the body method by which drugs are inactivated
pharmacokinetic (2): excretion
kidneys excrete water soluble form of drug (some drugs can be excretede from liver)
drugs must have what type of solubility to pass through the cellular membrane
lipid soluble (water soluble need a transport mechanism to cross)
if we give an drug PO/orally, what does it have to go through
first pass effect
what drugs are 100% bioavailable
IV drugs (PO drugs have a varying of
PO meds bio availability
the amount of drug left after the first pass effect (ex: if first pass is 20%, then the drugs bio avail is 80%)
when would you expect to see a high first pass %
if a drug is taken in a high amount (dose) or is taken often
high first pass % would give what type of bio availability %
low
the first pass effect alters
the amount of a drug that is absorbed
first pass effect
PO meds that are absorbed in the SI have to go through the liver to be turned into its active form before they can enter circulation and this determines their bio availability
routes of absorption (ROA)
enteral
parenteral
topical
enteric coated (EC) meds
intended to break down in the small intestine and not the stomach (still goes through first pass)
ROA: enteral
by way of the GI tract (oral/gastric mucosa, SI, rectum aka po meds & rectal)
PO meds break down starts in the “” and are absorbed in the “” and it does or does not go through first pass?
stomach ; small intestine ; does
what routes of enteral meds do not go through first pass and why
SL, buccal and rectal bc all sites contain highly vascularized tissue
why can you not make a PO drug rectal
no first pass effect due to the bio availability so it by passes the liver
ROA: parenteral
SQ, IM, IV, intrathecal (into spinal canal), epidural (space around the spinal cord)
do parenteral drugs go through first pass effect
no
what route of parental drug is fastest
IV bc there are no barriers to absorption (they are often irreversible)
ROA: topical (transdermal)
application of meds to body surfaces, has a slower onset & more prolonged interaction
do topical drugs go through first pass effect
“not concerned with first pass effect because it will act very localized”
where does the best drug distribution occur
in areas that are highly vascularized w/ good blood flow (decreased blood flow = decreased distribution)
condition that decrease blood flow
peripheral vascular disease, abscesses, tumors
blood brain barrior
cells in the capillary wall in the brain with very tight junctions that prevent drug passages (prevents drugs from going to the brain as a preventive mechanism)
what drugs can’t pass the blood brain barrier
only drugs that have transport systems or are “extremely” lipid soluble
what drugs can pass the blood brain barrier
alcohol, glucose (the brains source of energy)
what is a main consideration when giving drugs to infants
the blood brain barrier is not fully developed so more drugs can pass through
protein binding effect
temporary storage of drug molecule that allows drug to be available for a longer period of time, drugs bind to albumin but can rapidly be unbound
what type of drug, bounded or unbounded, is considered active and free exert effects
unbound (free)
what is the goal of protein binding
maintain a steady free drug concentration “steady state”