TOPIC 2 Flashcards
What are the pharmacokinetic phases?
absorption
distribution
metabolism
excretion
absorption
movement of the drug from the GI tract into the bloodstream after administration
distribution
movement of drugs from circulation into body tissues
metabolism (biotransformation)
body chemically changes drugs to a form that can be excreted
excretion
elimination of drugs from the body
disintegration
breakdown of oral drug into small particles
dissolution
process of combining small drug particles with liquid to form a solution
What are the two components of passive transport?
diffusion and facilitated transport
diffusion
drugs movement across cell membrane from high to low concentration
facilitated transport
relies on a carrier protein to move drug from high to low concentration
active transport
REQUIRES ENERGY (ATP) and carrier substance (enzyme)
pinocytosis
cell carries drug across membrane by engulfing drug particles
What are the factors that affect absorption?
blood circulation
pain, stress
food texture, fat content, temperature
pH
route of administration
How do drugs move from the GI tract to the liver?
via the hepatic portal vein
What is the first pass effect?
After oral administration, many drugs are absorbed intact from the small intestine and transported first via the portal system to the liver, where they undergo extensive metabolism, therefore usually decreasing the bioavailability of certain oral medications.
bioavailability
percent of administered drug available for activity
what reaches systemic circulation (blood stream)
Which has more bioavailability, oral route or IV?
oral route will have less bioavailability because it passes through the liver
IV administration bypasses the liver
What are factors that affect bioavailability?
drug form
route of administration
gastric mucosa and motility
administration with food and other drugs
changes in liver metabolism
What happens when 2 highly protein bound drugs are administer together?
the drugs will compete for protein binding sites and this will lead to an increase in the free drugs of the drug that had the lower percent of protein binding
free drugs
can exit blood vessels and reach their site of action causing pharmacological response
(too high of free drug accumulation can cause side effects, adverse effects, or toxicity)
What are the requirements of a drug to pass the blood brain barrier?
high lipid soluble
low molecular weight
and can pass with a transport protein
half life (t1/2)
time it takes for the amount of drug in the body to be reduced by half
loading dose
a large initial dose given to achieve a rapid minimum effective concentration in the plasma
therapeutic effects can be obtained while steady state is reached
Where is the primary site of metabolism?
liver
What lab test help determine if liver function is good?
aspirate transaminase (AST)
alanine aminotransferase (ALT)
alkaline phosphate (ALP)
Where is the main site of excretion?
kidneys
What helps determine kidney function?
creatinine clearance
BUN
GFR
Where can drugs be excreted?
kidneys (mainly)
liver (bile)
feces
lungs
saliva, sweat, breast milk
What can protein binding be affected by?
competition for protein binding sites
low plasma protein levels
What affects drug distribution?
blood flow to tissues
ability of drug to enter the cell
ability of drug to exit blood vessels
What are the 3 excretion processes? Explain each.
glomerular filtration: moving the drug from the blood to urine
passive reabsorption: lipid soluble drugs move back to blood
active transport: “pumps” for organic acid and base to move drugs from blood to urine
When the liver eliminates bile, in what form is it excreted?
excreted in feces
What kind of drugs have ready access to breast milk?
lipid-soluble
What are the factors that affect drug excretion?
drugs that affect renal excretion
drugs that decrease cardia output
use of diuretics
competition of drugs that undergo the same route of excretion
change of urine pH
patients with decreased renal to hepatic function
Acidic urine promotes elimination of
weak base drugs
Alkaline urine promotes elimination of
weak acid drug
What labs are taken to test kidney function?
creatinine (CR)
blood urea nitrogen (BUN)
pharmacodynamics
study of the way drugs affect the body
primary effect
desirable response of the drug
secondary effect
desirable or undesirable response of the drug
potency
amount of drug needed to elicit a specific physiologic response to a drug
therapeutic index
relationship between therapeutic and toxic dose
peak
highest concentration in the blood
onset
time it takes for drug to reach minimum effective concentration (therapeutic response)
duration
length of time for a drug to exert a therapeutic effect
peak drug level
the highest plasma concentration of a drug at a specific time
indicates the rate of absorption
trough drug level
the lowest plasma concentration of a drug
measures the rate at which the drug is eliminated
non-specific (non-selective) drugs
drugs that affect multiple receptor sites
agonist
activate receptors, produce a desired response
antagonists
prevent receptor activation, block response
Where are cholinergic receptors located?
bladder, heart, blood vessels, stomach, bronchi, and eyes
What receptors does epinephrine act on?
alpha and beta receptors
What are the mechanisms of drug action?
stimulation
depression
irritation
replacement
cytotoxic action
antimicrobial action
modification of immune status
stimulation drug
enhances intrinsic activity (increase heart rate, breathing rate, sweating, fight-or-flight response)
depressant drugs
decrease CNS (neural) activity and bodily functions
irritant drugs
have a noxious effect, such as astringents
replacement drugs
replace essential body compounds (insulin, thyroid drugs, hormone replacements)
cytotoxic drugs
selectively kill invading parasites or cancers
antimicrobial drugs
prevent, inhibit, or kill infectious organisms
immune modification drugs
modify, enhance or depress the immune system
side effects
secondary effects of drug therapy
What are some factors that play into side effect actions?
chronic illness, age, weight, gender, ethnicity
adverse drug reactions (ADRs)
unintentional, unexpected reactions to drug therapy that occur at normal drug dosages
drug toxicity
occurs when drug levels exceed the therapeutic range
pharmacogenetics
study of how genetics play a role in a persons response to drugs
tolerance
decreased responsiveness of a drug over the course of therapy (this individual would require a higher dosage of a drug to achieve the same therapeutic response)
Tachyphylaxis
rapid decrease in response to a drug
placebo effect
drug response not attributed to the chemical properties of the drug, influenced by the beliefs, attitudes and expectations
drug interactions
altered drug effect due to interaction with another drug
drug incompatibility
a chemical or physical reaction that occurs among two or more drugs in vitro (reaction occurs outside of the body- like in the IV or artificial environment)
pharmacokinetic interactions
changes that occur in the absorption, distribution, metabolism/biotransformation, and excretion of one or more drugs
additive effects
sum of the effects of the two drugs
synergistic effect
effect of the two drugs given together is much greater than effects of either drug alone
antagonistic effect
one drug reduces or blocks the effect of the other
drug nutrient interactions
food may increase, decrease, or delay drug response
drug laboratory interactions
drugs may cause misinterpretation of test results
drug induced photosensitivity
skin reaction caused by exposure to sunlight
genomics
study of all the genes in the human genome together, including their interactions with one another with one another, their interactions with the environment and the influence of other cultural and psychosocial factors
What is the purpose of knowing a patients genomic information?
so that treatments can be tailored/personalized per patient
carrier testing
testing to determine if a person “carries” the genetic variation that causes a disease
diagnostic testing
identifies genetic variation that is either causing a person to have a genetic condition/disease or may cause a condition in the future
