FPGEE Pharmacokinetics 4

Question 1

A drug has a hepatic extraction ratio of 0.9. Hepatic blood flow decreases by 50% due to heart failure. What is the expected effect on systemic clearance of this drug?

Accepted Answer

Clearance decreases by approximately 50%

Answer

For high-extraction drugs, clearance ≈ hepatic blood flow; a 50% reduction in flow causes an approximately 50% reduction in clearance.

Question 2

The renal clearance of a drug is found to be greater than GFR (125 mL/min). This indicates which renal mechanism?

Accepted Answer

Net tubular secretion

Answer

Renal clearance exceeding GFR means additional drug is being added to tubular fluid via active secretion beyond what filtration alone can account for.

Question 3

What is the time to reach steady state primarily dependent upon?

Accepted Answer

Drug half-life

Answer

Steady state is reached in approximately 4–5 half-lives regardless of dose size or frequency; half-life is the primary determinant.

Question 4

A drug's bioavailability is 30% by oral route. To achieve the same AUC as a 50 mg IV dose, the oral dose should be:

Accepted Answer

167 mg

Answer

Oral dose = IV dose / F = 50 mg / 0.30 ≈ 167 mg to compensate for the 70% lost to incomplete absorption and first-pass.

Question 5

Which plasma protein primarily binds basic (cationic) drugs such as lidocaine and propranolol?

Accepted Answer

Alpha-1-acid glycoprotein (AAG)

Answer

Alpha-1-acid glycoprotein preferentially binds basic drugs, while albumin primarily binds acidic drugs and some neutral drugs.

FPGEE Exam Practice Test

FPGEE Exam Practice Test

FPGEE Pharmacokinetics 4