PSA Pharmacology Principles 2

Question 1

A drug with a half-life of 6 hours is started at regular dosing intervals. Approximately when will it reach steady-state plasma concentration?

Accepted Answer

After 4-5 half-lives (24-30 hours)

Answer

Steady state is reached after approximately 4-5 half-lives, regardless of the dosing interval or dose size.

Question 2

Which route of administration most reliably bypasses hepatic first-pass metabolism?

Accepted Answer

Sublingual tablet

Answer

Sublingual administration allows drug absorption directly into systemic circulation via the sublingual veins, bypassing the portal circulation and hepatic first-pass effect.

Question 3

A drug has a volume of distribution (Vd) of 700 L. What does this indicate about the drug?

Accepted Answer

It is extensively distributed into peripheral tissues or fat

Answer

A large Vd (>100 L) indicates the drug distributes extensively into peripheral tissues or adipose tissue, with low plasma concentrations relative to total body drug.

Question 4

Creatinine clearance (CrCl) is primarily used to guide dose adjustment for which category of drugs?

Accepted Answer

Drugs that are predominantly renally excreted unchanged

Answer

CrCl estimates glomerular filtration rate and is used to adjust doses of renally excreted drugs (e.g., gentamicin, metformin) to prevent accumulation and toxicity.

Question 5

Why is a loading dose used when initiating therapy with certain drugs?

Accepted Answer

To rapidly achieve therapeutic plasma concentrations

Answer

A loading dose rapidly achieves therapeutic drug levels by filling the volume of distribution, which is particularly important for drugs with long half-lives where waiting for steady state would be clinically unacceptable.

(PSA) Prescribing Safety Assessment Practice Test

(PSA) Prescribing Safety Assessment Practice Test

PSA Pharmacology Principles 2