39 Questions
Which one of the following is the primary elimination route for many medications?
Glomerular filtration
What process is usually responsible for the active secretion of drugs into the urine?
Tubular secretion
What is the main factor that influences the process of tubular reabsorption?
Lipid solubility and degree of molecular ionization
How does the glomerular filtration rate (GFR) typically change as humans age?
GFR decreases gradually with age
Which of the following statements about tubular secretion is correct?
Tubular secretion is an active process conducted by relatively specific carriers or pumps
What is the primary factor that determines the extent of tubular reabsorption?
Lipid solubility and degree of molecular ionization
Which of the following equations describes the various routes of renal elimination?
$ ext{Renal elimination} = ext{Glomerular filtration} + ext{Tubular secretion} - ext{Tubular reabsorption}$
What is the typical range of glomerular filtration rate (GFR) in young, healthy adults between the ages of 18-22 years?
120-140 mL/min
What is the expected glomerular filtration rate for otherwise healthy, normal 80-year-old adults?
~30–40 mL/min
In patients with renal disease, what leads to the functional loss of nephrons?
Functional loss of nephrons
What is the usual normal range for glomerular filtration rate according to most clinical laboratories?
~80–120 mL/min
In acute renal failure, which of the following can lead to a sudden decrease in renal blood flow?
Hypovolemia
What is the formula for calculating creatinine clearance rates as per the text?
(UCr ⋅ Vurine) / (SCr ⋅ T)
Which type of patients are more likely to recover their kidney function to pre-insult level post-acute renal failure?
Patients with acute renal failure due to hypovolemia
What happens to patients with chronic renal failure according to the text?
They experience irreversible damage
How can creatinine clearance rates be measured according to the text?
By collecting urine for a specified period and collecting a blood sample for determination of serum creatinine at the midpoint of the concurrent urine collection time
What is the body surface area used for normalizing estimated creatinine clearance?
1.73 m2
In a patient with renal dysfunction, what can be done to achieve a concentration/time profile similar to that seen in a normal patient receiving the normal dose?
Decrease the dose and lengthen the dosage interval
What is the total daily dose for patients with renal disease receiving a dosage regimen of 150 mg every 6 hours?
600 mg/d
For liver-metabolized drugs in patients with hepatic dysfunction, what dosing options are usually available?
Decreasing the dose and lengthening the dosage interval
What effect does giving a smaller dose of a drug at the same dosage interval usually have on the concentration/time profile?
Lower peak steady-state concentration and higher trough steady-state concentration
What happens to the concentration/time profile when giving the same dose but prolonging the dosage interval in a patient with renal disease?
Higher peak steady-state concentration and lower trough steady-state concentration
What is the average steady-state concentration like when comparing renal disease dosage regimens?
Identical for both dosage schemes despite differences in peak and trough concentrations
What type of drug metabolism reactions are often mediated by the cytochrome P-450 enzyme system (CYP)?
Phase I reactions
Where is the cytochrome P-450 enzyme system (CYP) bound?
To the endoplasmic reticulum of hepatocytes
What type of enzymes may mediate Phase II drug metabolism reactions in the liver?
Cytosolic enzymes contained in hepatocytes
What is the general effect of Phase I and Phase II drug metabolism on the metabolites?
It makes the metabolites more water-soluble and less prone to elimination
What is the primary function of transport proteins, such as P-glycoprotein, in the liver?
To actively secrete drug molecules into the bile
What is the primary characteristic of hepatitis in patients?
Inflammation of the liver
How does acute hepatitis affect drug metabolism in patients?
It causes a mild, transient decrease in drug metabolism that may require no or minor dosage changes
What is the primary characteristic of hepatic cirrhosis in patients?
Permanent loss of functional hepatocytes
What is the Child-Pugh score range that indicates a moderate decrease (approximately 25%) in initial daily drug dose for agents primarily metabolized by the liver?
8-9
If a drug is 95% liver metabolized with a usual dose of 500 mg every 6 hours, what would be an appropriate initial dose for a hepatic cirrhosis patient with a Child-Pugh score of 12?
Both a and b
What is the Child-Pugh score range that indicates a significant decrease (approximately 50%) in initial daily dose for drugs that are mostly liver metabolized?
10 or greater
If a patient has normal liver function, what is their Child-Pugh score?
5
What is the Child-Pugh score for a patient with grossly abnormal serum albumin, total bilirubin, prothrombin time values, severe ascites, and hepatic encephalopathy?
15
If a drug is primarily metabolized by the liver, what percentage of the initial daily dose would be appropriate for a patient with a Child-Pugh score of 8?
75%
According to the information provided, which of the following statements is true?
Initial doses are meant as starting points for dosage titration based on patient response and avoidance of adverse effects.
What is the total daily dose of a medication that is 95% liver metabolized with a usual dose of 500 mg every 6 hours?
2000 mg/day
Test your knowledge on the renal elimination pathways of drugs, including glomerular filtration and tubular secretion in the kidneys. Learn about the primary routes through which medications are excreted from the body.
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