1. Mark true or false. A
renal clearance of 500 ml /min may suggest that:
is eliminated only by glomerular filtration
the drug is
eliminated by tubular secretion
interactions in renal tubules are likely
is probably nonionized
is extensively reabsorbed in renal tubules
2. Drug addicts sometimes
abuse amphetamines in combination with sodium bicarbonate.
What is the rationale of this emperically discovered
interaction? What could be done to enhance the detoxification
of an overdosed addict?
3. Which of the following
factors does NOT influence glomerular filtration:
number of functioning nephrons
renal blood flow
4. Select the correct
answer(s). A renal clearance of 500 ml/min may suggest:
elimination by glomerular filtration
high protein binding
elimination by tubular secretion
reabsorption in renal tubules
5. Mark whether following
statements are true or false
secretion depends on the pH of urine
ionized substances tend to remain in the urine
reabsorption can only be an active transport process
filtered across the glomerulus through passive diffusion
secretion most often occurs with weak organic acids
6. A drug is eliminated almost exclusively by hepatic
metabolism; renal and biliary excretion of unchanged drug
account for less than 1 percent of total drug elimination.
One route of metabolism is glucuronidation, with excretion of
all of the glucuronide into the bile (flow rate is 50 ml/hr),
at a concentration 110 times that of drug in blood. The
excreted glucuronide is neither hydrolyzed in nor reabsorbed
from the intestines. The volume of distribution VB (referenced to blood) and the half-life of
this drug are 100 liters and 9 hours, respectively.
a) Is glucuronidation a major (more than 50 percent) route
of elimination of the drug?
b) What is the hepatic extraction ratio of this drug?
Hepatic blood flow is 1.5 liters/min.
c) Is the clearance of this drug more likely to be
sensitive to a change in plasma protein binding or to a
change in hepatic perfusion?
d) Will the half-life of this drug be changed in a patient
with biliary obstruction? Briefly comment.
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