ABT Toxicokinetics and Metabolism

Question 1

Which pharmacokinetic parameter describes the fraction of an administered dose that reaches systemic circulation unchanged?

Accepted Answer

Bioavailability (F)

Answer

Volume of distribution (Vd)

Answer

Clearance (CL)

Answer

Half-life (t½)

Question 2

Which cytochrome P450 enzyme is responsible for metabolizing the largest number of pharmaceutical drugs (approximately 30–40%)?

Accepted Answer

CYP3A4

Answer

CYP1A2

Answer

CYP2C9

Answer

CYP2D6

Question 3

A chemical with a high volume of distribution (Vd > 10 L/kg) is most likely to be:

Accepted Answer

Highly lipophilic and distributed into peripheral tissues

Answer

Highly water-soluble and confined to plasma

Answer

Extensively bound to plasma proteins

Answer

Rapidly excreted by the kidneys without tissue binding

Question 4

First-order elimination kinetics means that:

Accepted Answer

The rate of elimination is directly proportional to the drug concentration

Answer

A constant amount of drug is eliminated per unit time regardless of concentration

Answer

Elimination rate increases exponentially with dose

Answer

Half-life increases as dose increases

Question 5

The hepatic extraction ratio (ER) of a drug determines whether its clearance is sensitive to changes in:

Accepted Answer

Hepatic blood flow for high-ER drugs and protein binding for low-ER drugs

Answer

Renal blood flow for high-ER drugs

Answer

GI motility only

Answer

Intestinal CYP expression for low-ER drugs only

Question 6

Which phase II biotransformation reaction is most important for detoxifying reactive electrophilic metabolites via conjugation with a tripeptide?

Accepted Answer

Glutathione conjugation (GST)

Answer

Glucuronidation (UGT)

Answer

Sulfation (SULT)

Answer

Acetylation (NAT)