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94 Cards in this Set

  • Front
  • Back
biopharmaceutics
the study of the relationship between the nature and intensity of the drugs biological effect and various drug formulation or administration factors
pharmacokinetics
a study of the time course of drug of absorption, distribution, metabolism, and excretion
Disposition
what occurs after the drug is absorbed (distribution & elimination)
Absorption
process by which unchanged drug proceeds from side of administration to sight of measurement within the body; the penetration of free drug molecules through a biological membrane
distribution
process of delivering drugs into body tissues and fluids following absorption
metabolism
chemical alteration of the drug in the body to a different chemical species
excretion
removal of intact drug or metabolite from the body
elimination
irreversible removal of drug from the body by all routes of elimination; the combined effort of biotransformation and excretion
absorption is dependent on
solubility, molecular weight, permeability
clinical pharmacokinetics
the application of pharmacokinetic principles to the safe and effective therapeutic management of drugs and an individual patient
objectives of clinical pharmacokinetics
1. initial design of drug ghosting regiment 2. refinement of dosing regimen based on serum samples 3. pharmcokinetic work-up 4. research
Pharmacodynamics
relationship between the drug concentration at the site of the action and pharmacologic response ; what the drug does to the body
therapeutic drug monitoring
the utilization of plasma drug concentrations and clinical data to individualize and optimize a patient's drug therapy
bioavailability
the percentage or fraction of the administered dose which reaches the systemic circulation
bioequivalence
comparison of bioavailabilities of different formulations, drug products, or batches of the same drug product
duration of action
the time the plasma concentration is above the MEC
lag time
the time that it takes for drugs to begin being absorbed
onset time
the time it takes the plasma drug concentration to reach the MEC
the intensity of the drug plasma concentration is proportional to
the number of drug receptor sites occupied
drug dosing regimen
dose, route, interval, etc
bioavailability (F) <1 because
absorption incomplete, degradation in GI tract, first pass metabolism
zero order
the amount of drug decreases at a constant rate
first order
the amount of drug decreases at a rate that is proportional to the amount of drug
nine routes of drug administration
IV bolus, IV infusion, IM, SC, SL, PO, PR, transdermal, inhalation
reasons to give drug intravenously
controlled rate, rapid response, drug has absorption difficulties or stability problems
reasons to give drugs orally
avoid high early toxic levels, avoid rapid allergic reactions, easy to administer, drug problems with physical or chemical stability of formulation
for a drug to be absorbed, it must first…
be dissolved in fluid at the absorption site (cannot pass through membrane in particulate form)
the most common rate limiting step in oral absorption
dissolution (there is also disintegration & GI transfer)
absorption of drug not complete
chemical nature of drug (very polar), dosage form, physiology of the patient
transcellular absorption
passage of molecule through cell membrane
paracellular absorption
that passage of molecules through pores in membrane
what form of the drug is absorbed better and why
unionized form, can cross membranes much easier (more lipid soluble)
the most common method for drug absorption
passive diffusion
passive diffusion
drug goes from area of high concentration to the area of low concentration
acidic drugs tend to be absorbed from
the stomach (low pH) *HA
basic drugs tend to be absorbed from
the intestine (high pH) *B
active transport
specialized transport mechanism whereby drugs are moved against a concentration gradient, requires a carrier, requires energy
drugs which utilize active transport are analogues of
endogenous substances
mechanisms of absorption
passive diffusion, active transport, facilitated diffusion, ion pair formation
facilitated diffusion
carrier mediated, does not require energy, can be saturated and and inhibited, moves along concentration gradient
ion pair formation
ionized drug links up with oppositely chared ion, forming a neutral pair (cation drug + anion carrier)
stomach pH
1 to 3
small intestine pH
5 to 8
large intestine pH
6 to 7
acidic drugs are soluble in the _____ and basic drugs are soluble in the ______
stomach, intestine
major area for absorption of drugs and nutrients
small intestine (huge surface area)
Gastic emptying rate
the rate of movement of the GI mass from the stomach to the duodenum
factors that alter gastric emptying rate
food, drug coadministration, body position, physiological status of patient
factors affecting drug distribution
cardiac output, plasma protein binding, chemical structure of drug
perfusion ratio
blood flow /tissue mass
highly perfused tissues
spleen, kidney, gut, pancreas, brain, heart, and lungs
__ of cardiac output is delivered to tissues that comprise less than __ of the body weight
3/4, 1/10
stronger acids --> _____ distribution
narrower
drug distribution patterns
remains within the vascular compartment, uniformly distributed through body water, concentrated in a particular tissue, non uniform distribution
drugs in the brain can only be eliminate by
the blood
drug penetration to the placenta is greater in
the third trimester
Ion trapping of _____ drugs occurs in the milk
basic
proteins involved in binding drug
albumin, alpha1 glycoprotein, lipoproteins
albumin
responsible for maintaining osmotic pressure of the blood and for transport of endogenous substances
binds to specific site on albumin
acidic drugs
extent to which a drug binds to albumin depends on
a affinity of drug to albumin, number of binding sites on albumin for particular drug, concentration of drug, concentration of albumin
alpha1 acid glycoprotein primarily binds
basic drugs
liver disease causes
decrease albumin concentration due to decreased protein synthesis
as free drug increases, drug distribution
increases
restrictive elimination
process of elimination which occurs only to unbound drugs
characteristics of restrictive elimination
drug tightly bound to protein, small plasma clearance, small hepatic extraction ratio
non restrictive elimination
process of elimination which occurs to protein bound rugs
characteristics of non restrictive elimination
drug weakly bound to protein, high liver extraction
major route for polar drug excretion
renal
mechanisms of renal secretion
glomerular filtration, secretion, reabsorption
glomerular filtration
unidirectional process of filtration through porous capillaries of bowman's capsule
secretion
active transport of drug from blood into urine, occurs in proximal tubule
reabsorption
mechanism for reuptake of drug, offsets effect of filtration, occurs in distal part of tubule
renal blood flow
1200mL/min or 1730 L/day
factors that affect renal excretion
drug protein binding, partition coefficient, urine PH, molecular size, active secretion properties
total body clearance
the volume of fluid cleared of drug per unit time by the entire body
organ clearance
measure of an organ's ability to clear a substance
renal clearance
the volume of plasma that is cleared of drug per unit time through the kidney
max renal clearance
650mL/min
if Clr is between 120-650mL/min
filtration & secretion taking place
if Clr is between 0-120mL/min
filtration & reabsorption are taking place
used to estimate renal function
inulin, creatinine
biliary excretion
drugs can be excreted from the liver into the bile by active transport
enterohepatic circulation
cycle in which the drug is absorbed from GI, excreted into bile, & reabsorbed
properties for biliary excretion
MW >500, strong polar group, active transport
three carriers for biliary excretion
organic anions, organic cations, non-ionized
biotransformation
chemical modification of parent drugs resulting in loss of drug from body
phase one reactions
oxidative, reduction, hydrolysis
oxidative reactions
aromatic hydoxylation, side chain hydroxylation, N- O- S-dealkylation, deamination, sulfoxidation, N-oxidation, N-hydoxylation
reduction reactions
azoreduction, nitroreduction, alcohol dehydrogenase
hydrolysis reactions
ester hydolysis, amide hydrolysis
phase two reactions
glucuronide conjugation, peptide conjugation, methylation, acetylation, sulfate conjugation, glutatione conjugation
glucuronide conjugation
esther glucoronide, ester glucoronide, amide glucuronide
major site of drug metabolism
liver