pharmocokinetics Flashcards
what is pharmacokinetics
the study of drug movement throughout the body. it focuses on what the body does to drugs after they are administered
drugs need to travel across many different
membranes and barriers
the drug’s travel is influenced by
factors related to the drug
factors related to the membranes
factors related to the transportation
cell membrane is a______ structure
dynamic
factors affecting the movement of drug from outside of the cell to inside of cell
- size
- lipid solubility
- ionization of molecule
drugs can use different ways to cross the plasma membrane
passive diffusion and facilitated
active transport
does passive diffusion require energy?
no
does facilitated diffusion require energy?
no
what is facilitated diffusion
is also known as facilitated transport or passive-mediated transport. it is the process whereby molecules such as glucose, sodium ions, and potassium ions cross through a cell membrane via carrier proteins down a concentration gradient without consumption of energy
does active transport requires energy?
yes . ATP
what is active transport?
movements of chemicals against a concentration gradient. fromm lower to higher concentration
primary processes of pharmacokinetics
absorption
distribution
metabolism
excretion
what is absorption?
process involving the movement of drug from the site of administration , across body membranes to the blood stream
most drugs are absorbed except for
intravenous or intra-arterial drugs
GI-anti infective/ deworming drugs
radiologic contrast media
factors affecting drug absorption
route of administration
drug formulation (ORAL/IV)
drug dosage
digestive motility- slower move- higher absorption
size of drug molecule
blood flow at administration site (IV/IM OR SL)
degree of ionization of drug
pH of surrounding environment
drug-drug/food/herbal interactions
high fatty foods- slow absorption
hydrophilic/ lipophilic
what is bioavailability of drug
the extent to which the active drug ingredient enters the systematic circulation and gains access to the site of action
formula of bioavalibility
quantity of drug reaching the systematic circulation/ quantity of drug administered
distribution involves the
transportation of drugs throughout the body
factors determining drug distribution
blood flow
physical properties of drugs
plasma protein binding
barriers
organs with more blood flow such as liver, kidneys, heart have _____ distribution of drugs compare to organs with ______ blood flow
higher, lower
__________ drug and certain tissues such as ________ have a _________ affinity/attraction for certain medications
lipid soluble, bone marrows, higher
how is drug-protein complexes forms
drug molecules form drug-protein complexes by binding reversibly to plasma protein
can drug-protein complexes cross capillary membranes?
yes
only _______ drugs can reach target tissues
unbound
drugs with ______ affinity for plasma protein will displace those with ______ affinity
weaker
what drugs have a high affinity for adipose tissues
thiopental, valium, fat soluble vitamins
what drugs have a high affinity for bones and teeth tissues
tetracycline
what drugs have a high affinity for eyes tissues
chloroquine
what drugs have a high affinity for muscle
digoxin
________ ( used to treat malaria) have high affinity to eye can damage the _______ in high doses
chloroquine, retine
what is a blood barrier brain?
a barrier that protects the brain from pathogens and toxins
structure of a blood barrier brain
it does not contain pores
lipid-soluble drugs able to cross
what medications can cross the blood barrier brain?
sedatives, L-dopa (used for Parkinson’s diesease ), antianxiety drugs
what is a Parkinson’s disease
it is a neurodegenerative condition, leads to the difficulty to walk, balance, tremors loss of facial expressions
what are the two types of barrier?
blood-brain barrier
fetal-placental barrier
what is metabolism
a biochemical reaction that changes the activity of a drug and makes it more likely to be excreted
the primary site of metabolism
liver
metabolism is done by the _________ enzymes
hepatic microsomal enzymes
the main system of enzymes in the hepatic microsomal system is
cytochrome P450
what do these cythochrome P450 do?
determine the at which drug is metabolized.
contribute largely to dru-drug interactions
