Q: A patient is given a drug intravenously (IV). What is the formula to calculate the initial concentration ($C_0$) in the systemic circulation?

$C_0 = \frac{\text{Dose}}{V_d}$

Question 1

Which of the following best describes the term 'bioavailability' in pharmacology?

Accepted Answer

The fraction of an administered drug dose that reaches the systemic circulation.

Question 2

A patient is given a drug intravenously (IV). What is the formula to calculate the initial concentration ($C_0$) in the systemic circulation?

Accepted Answer

$C_0 = \frac{	ext{Dose}}{V_d}$

Question 3

Which of the following mechanisms of drug transport is NOT saturable?

Accepted Answer

Passive diffusion

Question 4

A weak base drug is administered orally. In which part of the gastrointestinal tract will it be best absorbed?

Accepted Answer

Terminal ileum (higher pH)

Question 5

Which of the following statements about the first pass effect is correct?

Accepted Answer

It refers to the metabolism of a drug in the liver before it reaches systemic circulation.

Question 6

A patient is prescribed a drug that is a weak acid. To increase its renal excretion, what should be done to the urine pH?

Accepted Answer

Alkalinize the urine to trap the ionized form of the drug.

Question 7

Which of the following is a characteristic of passive diffusion across cell membranes?

Accepted Answer

It does not require energy and is not saturable.

Question 8

If you want to switch a patient from IV to oral administration of a drug and maintain the same amount reaching systemic circulation, what should you do to the oral dose?

Accepted Answer

Increase the oral dose to account for lower bioavailability.

Question 9

Which of the following best describes the volume of distribution ($V_d$) of a drug?

Accepted Answer

A theoretical volume that relates the amount of drug in the body to the concentration in plasma.

Question 10

A drug is highly protein-bound in plasma. What effect does this have on its volume of distribution ($V_d$)?

Accepted Answer

It decreases $V_d$ because more drug remains in the plasma.

Question 11

Which of the following is true regarding the absorption of aspirin (a weak acid) in the GI tract?

Accepted Answer

Aspirin is better absorbed in the duodenum than in the ileum due to less ionization.

Question 12

Which of the following best describes the role of P-glycoprotein in drug absorption?

Accepted Answer

It expels drugs back into the GI tract, reducing absorption.

Question 13

Which of the following is a reason to choose the sublingual route for drug administration?

Accepted Answer

To bypass the first pass effect and achieve rapid onset.

Question 14

Which of the following is a property of facilitated diffusion?

Accepted Answer

It is saturable and requires a carrier protein.

Question 15

A drug is administered orally and undergoes significant metabolism in the liver before reaching systemic circulation. What is this phenomenon called?

Accepted Answer

First pass effect

Question 16

Which of the following best describes the relationship between pH, pKa, and drug ionization for a weak acid?

Accepted Answer

When pH > pKa, the weak acid is more ionized.

Question 17

Which of the following is a characteristic of primary active transport?

Accepted Answer

It requires ATP hydrolysis to move drugs against their concentration gradient.

Question 18

A patient with a genetic deficiency in P-glycoprotein is likely to experience which of the following?

Accepted Answer

Increased absorption and potential toxicity of certain drugs.

Question 19

Which of the following is a reason why the small intestine is the primary site for absorption of most oral drugs?

Accepted Answer

It has a very large surface area due to villi and microvilli.

Question 20

Which of the following best describes the effect of increasing GI motility on drug absorption?

Accepted Answer

It decreases absorption by reducing residence time.

Key Principles in Pharmacokinetics: IV Dosing, Bioavailability, and Drug Elimination

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