Basic Kinetics Review questions

Most drugs are eliminated from the body by first-order kinetics. This implies that_________. A: The rate of decrease in plasma drug concentration is constant B: The rate of elimination is proportional to the drug concentration in plasma C: The half life of elimination is dependent on the initial drug concentration in plasma D: A plot of drug concentration in plasma versus time on a rectangular coordinate graph paper shows a straight line relationship

B

Which of the following can be considered true for apparent volume of distribution? A: It is a true physiological volume B: It gives us idea about the distribution of a drug in the body C: It is high for a drug, which is mostly concentrated in blood D: It can be calculated only when drug concentrations in blood and tissues are the same

B

Which one of the following is true for a drug that follows the kinetics of one compartment model? A: The distribution of the drug to the extravascular tissues is very slow B: The drug in the blood is in rapid equilibrium with drug in the extravascular tissues C: The drug does not penetrate the tissue D: Tissues and plasma have the same concentration of the drug

B

Which of the following statements is correct for measurement of drug concentration? A: Fluorescence immunoassay is a chromatographic method B: Drug in feces reflects only the unabsorbed drug after oral dose C: Both urine and feces are important in mass balance study D: Plasma is obtained by allowing blood to clot and centrifuging to remove cells and some proteins

C

Which of the following statements is not true regarding drug distribution and protein binding? A: If the dose is kept constant, the total plasma concentration of a drug depends only on its clearance B: Dose does not need to be changed if the protein binding of a low clearance drug is changed C: Dose always should be reduced when the total concentration of drug in plasma increases D: Half life of a drug depends on its clearance and apparent volume of distribution

C

Which of the following is true for the pharmacokinetics of digoxin? A: Is is well described by one compartment model B: Distribution of digoxin to tissue is instantaneous C: The plasma would be the prepheral compartment and muscle tissue would be the central compartment D: If terminal half-life is calculated, must make sure that distribution phase is complete

D

After injection of drug X, the plasma drug concentrations were determined at 2 hours and 5 hours with resulting concentration 1.2 mg/mL and 0.3 mg/mL, respectively. What is the area under the curve (AUC) between 2 and 5 hours? A: 2.3 mg/mL B: 3.2 mg/mL C: 3.2 ug/mL D: 23 ug/mL

a

Which of the following would be evidence that a drug is distributed in extravascular tissue? a) High apparent volume of distribution b) Low apparent volume of distribution c) High value of Cp0 d) High value of elimination rate constant e) Excretion in urine

a

In pharmacokinetics, the term rate refers to a change in which of the following measurements over time. A: Drug dose B: Concentration of drug in plasma C: Drug elimination D: Apparent volume of distribution

b

The onset time for a drug given orally is the time for the a) Drug to reach the peak plasma drug concentration b) Drug to reach the minimum effective concentration (MEC) c) Drug to reach minimum toxic concentration (MTC) d) Drug to begin to be eliminated from the body e) Drug to begin to be absorbed from the small intestine

b

The physiologic pharmacokinetic model a) Is also known as catenary model b) Is based on known anatomic and physiologic data c) Can not extrapolate human data from animal data d) Predicts drug concentration in various tissues by their enzymatic activity e) Body is represented by a single compartment

b

Which of the following is NOT true for kidneys? A: They can excrete the metabolites created from hepatic metabolism. B: They can regulate production of platelets. C: They have a role in controlling blood pressure. D: They receive about 20-25% of the cardiac output. E: They maintain body fluid volume.

b

Which of the following is correct for a first order reaction? a) Half-life is proportional to initial concentration. b) Half-life is constant. c) Reaction rate is not affected by concentration. d) The amount of drug decreases at a constant rate. e) The unit of the rate constant is mg/ml.hr1.

b

Which of the following statements is correct for measurement of drug concentration? a) Drug in feces reflects only the unabsorbed drug after oral dose b) Both urine and feces are important in mass balance study c) Drug concentration measured in saliva can not be used for therapeutic drug monitoring d) Plasma is obtained by allowing blood to clot, and then centrifuging to remove cells & some proteins e) Chromatographic methods for drug analysis are less discriminating since they cannot separate the drug from the interfering materials

b

Which type of plasma protein mostly binds to cationic drugs? A: Albumin B: α1-Acid glycoprotein C: Very low density lipoproteins D: Low density lipoproteins E: High density lipoproteins

b

Calculate the percent protein bound of a drug in tissues, if plasma protein binding and volume of distribution of the drug are 40% and 200 L, respectively. The volumes of plasma and tissue are 3 L and 39 L, respectively. A: 8% B: 12% C: 88% D: 92% E: 99%

c

Elimination of a drug is the ___________________________________ a) Process by which unchanged drug proceeds from the site of administration to the site of measurement b) Reversible transfer of a drug to and from the site of measurement within the body c) Irreversible loss of drug from the site of measurement d) Distribution and protein binding in the body e) Non-enzymatic hydrolysis of the drug in intestine

c

One compartment open model means ____________________________ a) The drug is restricted to extracellular fluid b) The drug does not penetrate tissues c) One exponential term describes decreasing concentration of the drug in plasma d) Tissues and plasma have the same concentration of the drug e) The elimination of the drug is a zero-order process

c

A patient is a 20 years old male with newly diagnosed complex partial seizures. He received 700 mg of drug through IV single dose. The plasma concentration after 1 hour was 80 mg/mL and 10 mg/mL after 12 hours. What is the elimination rate constant and half-life? A:k=3.7hr, t1/2=0.2hr-1 B: k = 3.7 hr-1, t1/2 = 0.2 hr C:k=1.3hr, t1/2=4.7hr D: k = 0.2 hr-1, t1/2 = 3.7 hr

d

A patient was given 200 mg of drug Y. The initial concentration of Y in the plasma was 4 mg/mL. What is the apparent volume of distribution? A: 25 L B: 25 mL C: 50 L D: 50 mL

d

For drugs that exhibit the characteristics of two compartment model after i.v. administration: a) The natural log of plasma drug concentration versus time curve is represented by a mono- exponential curve. b) The first portion of the log of plasma drug concentration versus time curve, where the log concentration rapidly declines, is known as the elimination phase. c) The body is represented by a central compartment only. d) The concept of the residuals attempts to separate the two processes of elimination and distribution. e) Volume of the central compartment and (Vd) are same.

d

If the glomerular filtration of a drug is 96 ml/min, what portion of the drug is bound to plasma protein assuming 0/5GFR to be 120 ml/min? A: 0% B: 24% C: 96% D: 20% E: 100%

d

The pharmacokinetics of a drug is described by one compartment model and has an elimination half life of 8 hours in patient LK. How long it will take to eliminate 87.5% of an i.v. bolus dose of the drug in LK? a) 10hr b) 16hr c) 18hrd) 24hre) 48hr

d

Which of the following is correct for a zero order reaction? A: Half-life is constant B: Half-life is not proportional to initial concentration C: Reaction rate is affected by concentration D: The unit of the rate constant is (mg/mL)/hour

d

Which of the following is not considered part of the central compartment? a) Heart b) Highly perfused tissues c) Blood d) Liver e) Muscle

e

Which of the following is true for glomerular filtration? A: Large drug molecules can be excreted by glomerular filtration. B: Only nonionized drugs can cross glomeruli. C: Glomerular filtration rate is about 1200 ml/min D: It is an active transport process. E: Protein bound drugs are not excreted by glomerular filtration.

e