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50 Cards in this Set
- Front
- Back
what are the major mechanisms of renal elimination?
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(1) glomerular filtration (2) tubular secretion (3) tubular reabsorption (4) storage
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what is glomerular filtration important for?
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the small surface area is important for low ER drugs
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how efficient is glomerular filtration?
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low efficiency mechanism due to relatively small blood distrubution
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why is a glomerular filtration a low efficiency mechanism?
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relatively small blood distribution
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how much drug is cleared by glomerular filtration?
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only a small fraction of drugs are cleared by this mechanism
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what type of drugs undergo glomerular filtration?
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non-protein bound drugs ONLY; very influenced by binding to plasma proteins because drug bound to protein will not cross glomerulus
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do protein bound drugs undergo glomerular filtration?
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No
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how is renal clearance measured?
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via glomerular filtration using exogenous (inulin) and endogenous (creatinine)
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what is inulin and creatinine useful for?
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to measure renal clearance via glomerular filtration
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is inulin exogenous or endogenous?
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exogenous
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is creatinine exogenous or endogenous?
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endogenous
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is inulin or creatinin exogenous?
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inulin
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is creatinine or inulin endogenous?
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creatinine
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what is tubular secretion important for?
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high ER drugs
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describe the clearance of high ER drugs in tubular secretion?
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Cl approaches renal Q
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tubular secretion is an active process for what?
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specific acid/bases
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is tubular secteion a saturable process?
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yes
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there is competition between what in tubular secretion?
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between weak acids
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give examples of drugs that are weak acids and compete at tubular secretion?
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probenecid competes with penicillin and prolongs plasma concentration
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when does probenecid competes with penicillin and prolongs plasma concentration?
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as a result of competition between weak acids in tubular secretion
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Is tubular secretion limited by plasma protein binding?
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tubular secretion is NOT limited by plasma protein binding because drug has greater affinity for carrier protein in nephraon than plasma protein
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doesthe drug in tubules have greater affinity for carrier proteins in nephron or for plasm proteins?
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carrier proteins in the neprhon
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how is the clearance of a drug altered by tubular secretion?
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clearance is greater than if it was cleared by filtration alone
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what type of process is tubular reabsorption?
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active & passive
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what is tubular reabsorption affected by?
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influenced by urine flow rate, drug lipophilicty, pH
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what part of renal elimination is influence by urine flow rate,drug lipophilicity, and pH?
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tubular reabsorption
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what does pH modification affect in tubular reabsorption?
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certain toxicoses
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certain toxicoses undergo pH modification where?
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tubular reabsorption
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name some toxicoses that undergo pH modification in tubular reabsorption?
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salicylate, quinidine intoxication
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salicylate and quinidine intoxication undergo pH modification where?
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tubular reabsorption
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how does renal clearance participate in storage?
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pinocytosis
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what does pinocytosis cause in renal elimination?
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prolonged tissue elimination
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what drug undergoes pinocytosis in the kidney?
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aminoglycosides such as gentamicin
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aminoglycosides such as gentamicin under what in the kidney?
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pinocytosis
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how is the rate of excretion illustrated in renal elimination?
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rate of excretion = rate of filtration + rate of secretion - rate of reabsorption
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what factors influence renal clearance?
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(1) plasma drug concentration (2) plasma protein binding (3) pH reabsorption
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plasma drug concentration, plasma protein binding, and pH reabsorption influences what?
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renal clearance
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what does plasma drug concentration affect in renal elimination?
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filtration and reabsorption are not affected while active secretion decreases with increasing plasma concentration
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is filtration and reabsorption in renal elimination affected by plasma drug concentration?
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Not affected
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why is filtration and reabsorption not affected by plasma drug concentration?
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they are passive processes with rates proportional to plasma concentration and have a linear relationship
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what is the relationship between filtration/reabsorption and plasma drug concentration?
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linear
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is active secretion in renal elimination affected by plasma drug concentration?
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yes, it decreases with increasing plasma concentration, but we only see this saturation effect with VERY high plasma concentrations
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what type of relationship does active secretion have with plasma drug concentration in renal elimination?
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asymptotic relationship, it is saturable with maximum capacity
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how does plasma protein binding affect renal elimination?
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it only affects filtration of low ER drugs, not secretion
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does plasma protein binding affect filtration of low ER drugs or secretion in renal elimination?
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only affects filtration (low ER drugs), not secretion
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what factor affects filtrtion of low ER drugs but not secretion?
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plasma protein binding
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how does pH reaborption affect weak acids in renal elimination?
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weak acids are reabsorbed if acidic environment
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how does pH reabsorption affect weak bases?
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weak bases are reabsorbed if basic environment
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how does pH reabsorption affect polar basic drugs?
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not reabsorbed (Very small)
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what are pH-sensitive reabsorption drugs dependent on?
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flow dependence
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