week 2: Ch. 3-4 [Pharmacokinetics/dynamics] Flashcards
Pharmaco means:
medicine
Kinetics means:
movement
Pharmacokinetics means:
what the body does to drugs after administration
[study of drug movement throughout body]
What are 2 barriers to drugs attempting to reach target cells?
Many membranes must be crossed
Physiological processes
4 processes of Pharmacokinetics
absorption
distribution
metabolism
excretion
Drugs use _________ and ______ __________ to cross plasma membranes to reach target cells
diffusion, active transport
2 types of diffusion:
simple diffusion
passive transport
diffusion is the movement of a chemical from an area of :
higher to lower concentration
diffusion assumes a chemical can cross :
plasma membranes freely
[not the case for all drugs]
What factors affect movement across plasma membranes?
size of drug molecule
ionization of drug molecule
lipid solubility
Facilitated diffusion utilizes ____1____ ________ to cross membranes.
does it require energy? 2:
carrier proteins
2- no
Active transport pumps require:
cell energy
_________ is the first step toward reaching the target cell for a drug
Absorption
Absorption is the movement from site of administration to:
bloodstream
The primary factor for determining the onset of drug action:
absorption
Enteral route of administration
Drugs delivered to__________________
~orally or through ______________________________________________________________
~common: ______________________
[slow onset bc must absorb as goes through system to be available]
~Oral liquid absorbed much faster
Drugs delivered to GI tract
~orally or through NG tube or gastromy tubes
~common: tablets/capsules [slow onset bc must absorb as goes through system to be available]
~Oral liquid absorbed much faster
Explain enteric-coated tablet/capsule
Hard, waxy coating to resist ________________________________contents
~designed to dissolve in _____________ environment of small intestine
Hard, waxy coating to resist strongly acidic stomach contents
~designed to dissolve in alkaline environment of small intestine
Explain extended-release tablets/capsule
Designed to dissolve ____________ over longer time = ____________duration of action
Designed to dissolve slowly over longer time = longer duration of action
The following should never be chewed/crushed/opened:
extended-release formulations
enteric coated drugs
oral cavity drugs
Tablets/capsules go through a first-pass effect: drugs absorbed from the stomach and small intestine travel to liver, where they may be:
inactivated before reaching target organs
Recent devlopments of med administration (within enteral route) include
orally disintegrating tablets ODT
oral soluble films
Describe sublingual/buccal routine of medication (enteral)
medications kept in mouth
dissolves in_____________________
not subjected to ______________________________________________________________
sublingual- _____________
buccal- ___________________
[in case of multiple meds, oral meds first, then sublingual]
medications kept in mouth
dissolves in under 30 seconds
not subjected to stomach acid/ first-pass effect
sublingual- under tongue
buccal- in cheek
[in case of multiple meds, oral meds first, then sublingual]
Explain medications given through nasogastric and gastromy tubes
drugs usually_____________, to prevent _____________________
do not use ________________________ meds
drugs usually liquid, to prevent clogging tubes
do not use sustained release meds
Explain absorption of topical route meds
usually_________ absorption
drugs must penetrate ___________________________
ex) ________________ patch- like sticker- rate of delivery varies; can depend on amount of ______
usually slower absorption
drugs must penetrate thick skin layer
ex) transdermal patch- like sticker- rate of delivery varies; can depend on amount of hair
3 types of topical routines include
opthalmic route-
otic roue-
intranasal route-
vaginal route-
rectal route-
opthalmic route- treating local conditions in eye
otic route- in ear
intranasal route- within nose
vaginal route- local conditions or BC
rectal route- local or systemic; ex) suppository or enema; avoids first-pass effect
Describe parenteral route of drug administration
______________ & ______________ administration
~any medication penetrating through skin
~__________________ adminstration- drug into large muscle (thigh/arm/bottom); rapid onset of action
~_______________ administration: directly to bloodstream; fastest onset but most dangerous [miscalculation or reaction can lead to bad outcome]
intradermal & subcutaneous administration
~any medication penetrating through skin
~intra muscular adminstration- drug into large muscle (thigh/arm/bottom); rapid onset of action
~intravenous administration: directly to bloodstream; fastest onset but most dangerous [miscalculation or reaction can lead to bad outcome]
major difference between intradermal & subcutaneous administration
depth of injection
[intradermal more superficial]
Examples of subcutaneous administration drugs:
insulin
heparin
vitamins
vaccines
for most drugs, higher doses produce:
faster and greater drug response
& greater concentration gradient for diffusion
Most absorption of drug occurs in:
GI tract (small intestine)
why does digestive motility vary among patients?
different amount of acid in stomach, or quicker digestion
Presence of food in stomach _______ absorption
slows
[with very few exceptions]
Usually best to take med on empty stomach or between meals
Drugs are absorbed faster from areas of the body where blood flow:
is high
How can blood flow be purposefully manipulated to slow absorption?
vasoconstrictors [constricts blood flow]
ice packs
Depending on the pH of surrounding fluid, most drugs are either :
charged or uncharged state
__________ of a drug affects its ability to cross plasma membranes and to be excreted by the body
Ionization
acids are absorbed in acids because they are:
nonionized
bases are absorbed in bases because they are:
nonionized
Drug interactions can be-
drug-drug
or drug-food
drug interactions can potentially affect-
absorption of drugs
high fat meals can slow:
stomach motility
Drugs are absorbed faster when applied to:
regions with larger surfacer area, like small intestine or lung
Distribution describes movement of medication throughout the body after
absorption
What 4 factors affect drug distribution?
___________ to tissues
drug ___________
tissue __________
drug-protein ___________
blood flow to tissues
drug solubility
tissue storage
drug-protein binding
drug-protein complexes cannot cross :
capillary membranes
only ________ drugs reach target cells
unbound
What does the blood brain barrier do?
special anatomic _________
protects brain from ____________________________
____________________ drugs are able to cross
[not fully developed in neonates]
Inflammation can increase ____________________
special anatomic barriers
protects brain from pathogens and toxins
lipid-soluble drugs are able to cross
[not fully developed in neonates]
Inflammation can increase permeability
Fetal-placenta barrier prevents harmful substances passing from:
mother’s bloodstream to fetus
[not as efficient as blood brain barrier]
Inefficient with- alcohol, cocaine, caffeine, prescriptions can cross
metabolism __________ the structure and function of drugs, nutrients, vitamins, and minerals
alters
where is the primary site of metabolism?
liver
What are prodrugs?
medications that require ________________ to produce their __________________
~no pharmacological activity until after _______________
medications that require metabolism to produce their therapeutic actions
~no pharmacological activity until after metabolized
What is a hepatic microsomal enzyme?
enzyme____________ CYP450
an enzyme that _________________ many drugs
enzyme complex CYP450
an enzyme that metabolizes many drugs
3 important consequences of CYP systems
drugs as substrates
~may lead to _____________________________
drugs as enzyme inhibitors
~can contribute to _________________________in body
drugs as enzyme inducers
~accelerate metabolism; drug level may _________________
drugs as substrates
~may lead to drug-drug interactions
drugs as enzyme inhibitors
~can contribute to drug toxicity in body
drugs as enzyme inducers
~accelerate metabolism; drug level may decrease rapidly
Metabolism can vary due to genetic variations of _____ enzymes
CYP
Enzyme activity is often _______ in older adults
reduced
Liver impairment can lead to _________ metabolism
decreased
Excretion is the process of:
removing drugs from the body
Rate of excretion is determined by the
drug blood level
Renal excretion occurs in
the kidney
Drug excretion depends on urine:
pH
[urine pH can be manipulated to help with drug excretion]
Glandular secretion of drugs can happen in
saliva, sweat, breast milk
Pulmonary excretion (example)
gases, volatile liquids
Biliary excretion- some drugs are:
secreted in the bile
drugs excreted into the bile will eventually leave in the
feces
Enterohepatic recirculation:
drug reabsorbed and goes back into _______________________________may recirculate drugs, metabolites, and prolong action
drug reabsorbed and goes back into hepatic system may recirculate drugs, metabolites, and prolong action
The therapeutic response of most drugs depends on their concentration in:
the plasma
What is the minimum effective concentration?
amount of drug required to produce a therapeutic effect
________ concentration is level of drug that results in serious adverse effects
Toxic
What is the therapeutic range of a drug?
range where the drug produces desired actions
after peaking, drug plasma levels fall due to excretion
The drug half-life provides an estimation of:
duration of action
Plasma half-life is the time required for plasma concentration of drug to:
decrease by half
If a drug has a short half-life, it is given
given more frequently
A loading dose is a higher amount of drug given to:
“prime” the bloodstream
[increase level at the beginning]
a maintenance drug dose will keep concentration within:
therapeutic range
Pharmacodynamics- how a drug
changes the body
[involves drug mechanism of action]
[involves effect of drug concentration on body responses]
the median effective dose is the desired drug response in:
50% of subjects
The median lethal dose is
lethal to 50% of animals during testing
The median toxicity dose is the dose that produces
toxicity in 50% of subjects
[animal data/ clinical trial data]
The margin of safety MOS is the amount of drug lethal to
____of animals divided by amount of drug that produces _________________ effect in ______ of animals
1% of animals divided by amount of drug that produces therapeutic effect in 99% of animals
Three phases of dose-response relationship
Phase 1- lowest dose
phase 2- most desirable range
phase 3- plateau reached
Potency is the amount of drug needed to produce
a specified effect
Receptor theory- most drugs produce their actions by activating or inhibiting:
specific cellular receptors
Medications bind to receptors like a
lock and key
Agonists ________ the action of endogenous substances
mimics
Antagonists prevent action of:
endogenous substances
Pharmacogenetics is the branch of pharmacology that studies:
role of genetic variation in drug responses
ex) human genome project
