Pharmacy Pharmacokinetics

Question 1

What does 'bioavailability' refer to in pharmacokinetics?

Accepted Answer

The fraction of an administered dose that reaches systemic circulation unchanged

Answer

Bioavailability is the fraction (F) of an administered dose that reaches the systemic circulation in unchanged form, making it available for therapeutic effect.

Question 2

Which route of administration achieves 100% bioavailability?

Accepted Answer

Intravenous

Answer

Intravenous (IV) administration delivers drug directly into systemic circulation, bypassing all absorption barriers, and is the reference standard for 100% bioavailability.

Question 3

The 'first-pass effect' primarily occurs in which organ?

Accepted Answer

Liver

Answer

The first-pass effect (presystemic metabolism) primarily occurs in the liver, where orally absorbed drugs are extensively metabolized before reaching systemic circulation, significantly reducing bioavailability.

Question 4

Volume of distribution (Vd) is best defined as:

Accepted Answer

The theoretical volume needed to contain all drug at the observed plasma concentration

Answer

Vd is a theoretical (apparent) volume that relates the total amount of drug in the body to the measured plasma concentration; it does not correspond to a real physiological volume.

Question 5

A drug with a high volume of distribution (Vd > 20 L/kg) is most likely:

Accepted Answer

Extensively distributed to peripheral tissues

Answer

A high Vd indicates the drug distributes widely outside the plasma into peripheral tissues (e.g., fat, muscle), resulting in low plasma concentrations relative to total body drug.

Pharmacy Practice Test

Pharmacy Practice Test

Pharmacy Pharmacokinetics