Q: A patient receives a maintenance dose (MD) every 8 hours. Which equation best describes the relationship for IV administration?

$$MD = Cl \times Css \times \tau$$

Question 1

Which of the following best describes the difference between first order and zero order elimination kinetics?

Accepted Answer

First order elimination is proportional to drug concentration, while zero order elimination is constant regardless of drug concentration.

Question 2

A drug has a half-life ($$t_{1/2}) of 8 $$hours. How much of the drug remains after 24 hours, assuming first order elimination?

Accepted Answer

25%

Question 3

Which equation correctly relates clearance (Cl), volume of distribution (Vd), and elimination rate constant (ke)?

Accepted Answer

$$Cl = ke 	imes Vd$$

Question 4

A drug is administered orally with a bioavailability ($$F) of 0.25. If $$the recommended IV dose is 10 mg, what oral dose should be given to achieve the same systemic exposure?

Accepted Answer

40 mg

Question 5

What is the therapeutic index (TI) for a drug with $$TD_{50} = 20 mg/kg $$and $$ED_{50} = 2 mg/kg$$?

Accepted Answer

10

Question 6

Which of the following drugs is most likely to exhibit zero order elimination at high concentrations?

Accepted Answer

Phenytoin

Question 7

If a drug is eliminated by both metabolism in the liver and excretion by the kidney, which patient condition would most likely require dose adjustment?

Accepted Answer

Renal impairment when the drug is predominantly eliminated unchanged by the kidney

Question 8

How many half-lives does it take to reach steady state concentration for a drug given by repeated maintenance doses?

Accepted Answer

5

Question 9

Which formula is used to calculate the loading dose (LD) for IV administration?

Accepted Answer

$$LD = C_{desired} 	imes Vd$$

Question 10

A patient receives a maintenance dose (MD) every 8 hours. Which equation best describes the relationship for IV administration?

Accepted Answer

$$MD = Cl 	imes Css 	imes 	au$$

Question 11

If the steady state concentration (Css) is the same for two dosing regimens, but one regimen uses higher doses less frequently, what clinical consequence might occur?

Accepted Answer

Greater fluctuation between peak and trough concentrations, increasing risk of toxicity and reduced efficacy

Question 12

Which of the following best describes the concept of volume of distribution (Vd)?

Accepted Answer

The theoretical volume in which the total amount of drug would need to be uniformly distributed to produce the observed blood concentration

Question 13

A drug is administered repeatedly at the same dose and frequency. What is the expected outcome after several doses?

Accepted Answer

The drug concentration will approach a steady state

Question 14

Which PK parameter has units of $$L/hr$$?

Accepted Answer

Clearance (Cl)

Question 15

If a drug's elimination follows first order kinetics, what happens to the rate of elimination as drug concentration increases?

Accepted Answer

The rate of elimination increases proportionally

Question 16

Which equation describes the relationship between half-life ($$t_{1/2}) $$and elimination rate constant ($$ke$$)?

Accepted Answer

$$t_{1/2} = 0.693 / ke$$

Question 17

Which scenario would most likely require a loading dose?

Accepted Answer

When immediate therapeutic effect is needed and waiting for steady state is not feasible

Question 18

What is the main assumption of pharmacokinetics (PK) in clinical dosing?

Accepted Answer

Drug response is proportional to drug levels in the blood

Question 19

Which of the following is NOT a factor affecting drug clearance?

Accepted Answer

Patient's blood type

Question 20

If a drug is considered eliminated after 5 half-lives, what percentage of the drug remains in the body?

Accepted Answer

About 3%

Pharmacokinetics: Principles and Clinical Applications

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