Pharmacokinetics( Week 2)
what is biotransformation?
pharmacokinetics involves the study of these 4 things:
absorption, distribution, metabolism, excretion
this is where a larger amount of a drug is given to reach effects more quickly, then is given at a maintenance dose at following doses.
this is the amount of drug needed to cause a therapeutic effect:
this is the actual concentration of a drug that reaches the body and results from this:
absorption from the liver,
distribution to active site,
biotransformation in the liver,
excretion from the body are all components of this:
this is the process that occurs from the time the drug enters the body to the time it enters the bloodstream to be circulated:
the onset of action during absorption is determined these 5 things:
route of administration,
blood flow to the site of administration,
Presence of food or other drugs
These class drugs are virtually 100% bioavailable:
Distribution is this by definition:
movement of a drug to the body
distribution of a drug is largely dependant on this:
the adequacy of blood circulation
protein binding is when when:
drug molecules that bind to plasma proteins are pharmacologically inactive.
only ____ or ___ portion of the drug acts on body cells:
free or unbound
protein binding allows for part of the drug to be used now, and part to be:
stored and released as needed
what does the blood brain barrier do?
limits distribution of drugs to the CNS
Is the blood brain barrier selectively permeable?
only these drugs can cross the blood brain barrier to achieve therapeutic concentrations in the brain:
lipid soluble drugs or drugs with a transport system
What is biotransformation/ metabolism?
method by which drugs are inactivated by the body
this is initially inactive and exert no pharmacologic effect until metabolized:
kidneys olny excrete ____ soluble drugs
this organ converts lipid soluble drugs into water soluble drugs so that the kidneys can excrete them:
this influences the metabolism by producing different responses to drugs in ethnic groups or specific individuals:
this is and enzyme produced in the liver to metabolize drugs
What is first pass effect?
when drugs are given orally and are absorbed by the GI tract and carried directly to the liver where some metabolizing occurs, causing only part of the dose to reach systemic circulation and decreases bioavailability to the body
the elimination of a drug from the body
name 4 ways the body excretes drugs:
through skin, bowels, kidneys, lungs
drugs/ metabolites that are excreted in bile, reabsorbed in the small intestine and returned to the liver for further metabolism and excretion in urine is called this:
true or false.... some drugs given orally are never absorbed and go right to excretion:
this disease leads to the accumulation of numerous drugs and can cause severe adverse effects of dose is not reduced:
severe kidney disease
serums half life is also called:
elimination half life
serum half life is sefined as:
time required for serum concentration of a drug to decrease by 50%; determined by rates of metabolism and excretion
with a short half life, drugs need to be administered...
the amount of drug given must be equal to the amount eliminated. when dose is changed it will take an additional 4-5 half lives to reestablish equilibrium. this is called:
steady- state conditions
what is a serum drug level:
measurement of the amount of drug in the body at a specific time
this is when enough drug is present to exert its pharmacologic action on body cells:
MEC ( minimum effective concentration)
serum drug level and testing is especially useful when dealing with these drugs:
drugs with a narrow margin of safety
do most drugs like being taken with food? why?
no, because digestion of food often delays absorption and alters GI secretions and motility
treatment for warfarin is:
tyramine causes reaction with:
do not take tetracyclines with ___, as it binds together into a non-absorbable compund
this food inhibits the metabolism of drugs normally by a certain enzyme:
this drug-drug interaction increases effects; occurs when 2 drugs with similar pharmacological actions are taken
this drug- drug effect increases effects; 2 drugs with different sites/ mechanisms of action produce greater effects when taken together
this drug-drug interaction is where one drug causes the other drug to have intensified effects [such as cimetidine and benzodiazepine]
this drug- drug interaction is where one drug pushes off the protein to cause increased effects of the displaced drug:
this drug-drug interaction decreases effects, is given to antagonize the toxic effect of another drug:
this drug-drug interaction decreases effect by the drug combining to make nonabsorbable compounds
decreased intestinal absorption
this drug-drug interaction increases metabolism causing a decreased effect:
activation of a drug metabolizing enzymes in the liver
these 5 variables are things can affect drugs and how well they work:
age, weight, genetics, gender, pregnancy
what is a psychological variable when it comes to drugs and how well they work for someone?
why are infants at an increased risk for toxicity?
low plasma protein levels during first year of life
why are there so many variables to consider when giving infants/ young children drugs?
constant change and flux of immune system, total body water, fat stores, protein levels
absorption in particular is effected by 5 things:
2. gastric emptying
3. intestinal motility
4. route of admin
5. skin permeability
in pediatrics, distribution is affected depending on 3 things:
percent of body water, degree of protein binding, development of BBB
in pediatrics, metabolism is affected by this in the liver:
elimination is affected by this in pediatrics:
immature kidneys, a reduced GFR, and slower renal clearance
What is Beers Criteria?
dr. mark beers list of potentially inappropriate meds used by older adult population in 1997 ex. cimetidine causes confusion and others cause renal toxicity
this elevated blood value indicates that an older person is already at risk for renal/ drug toxicity
cross tolerance is different to regular tolerance how?
cross tolerance is when the patient grows tolerant of pharmacologically related drugs. also creates issues such as alcoholics needing more anesthetics and sedatives
when therapeutic effect is not being seen with oral drug, what should the nurse consider why?
blood flow to muscle beds, food altering make up in gastric juices, weight of patient, temperature of peripheral environment
this is an adverse effect:
refers to any undesired response to drug administration
give a primary adverse affect:
simple overdose of desired effect
give a secondary adverse effect:
other effect in addition to desired drug effect, sometimes unavoidable [ex. antibiotics causing diarrhea
give an example of hypersensitivity adverse effect:
exaggerated adverse effect, sometimes due to underlying condition
give an example of adverse effect effect via drug allergy:
anaphylactic response, ex person allergic to amoxicillin
when giving atropine like drugs [anticholinergics] watch for these:
dry mouth, altered taste, and urinary retention
WHAT IS TERATOGENICITY?
many drugs reach the developing fetus and can cause damage or death