Pharmacokinetics and Pharmacodynamics Flashcards
6 cards from real Pharm.D. Doctor of Pharmacy practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Pharmacokinetics and Pharmacodynamics flashcards as text
Which pharmacokinetic parameter describes the volume of plasma cleared of a drug per unit time?
Answer: Clearance
Clearance (CL) is the pharmacokinetic parameter that represents the volume of plasma cleared of a drug per unit time, typically expressed in L/hr or mL/min.
A drug has a half-life of 6 hours. Approximately how long does it take to reach steady-state concentration?
Answer: 24–30 hours
Steady state is reached after approximately 4–5 half-lives, so a drug with a 6-hour half-life reaches steady state in about 24–30 hours.
Which of the following best defines the volume of distribution (Vd)?
Answer: A proportionality constant relating plasma concentration to total drug in the body
Volume of distribution is an apparent proportionality constant that relates the total amount of drug in the body to the measured plasma concentration.
What is the effect of first-pass metabolism on oral bioavailability?
Answer: Decreases bioavailability
First-pass (hepatic) metabolism reduces oral bioavailability by metabolizing a significant fraction of the drug before it reaches systemic circulation.
Which pharmacodynamic concept describes the relationship between drug concentration and the maximum possible effect?
Answer: Emax model
The Emax model describes the relationship between drug concentration and effect, where Emax is the maximum achievable pharmacological response.
A drug following zero-order kinetics is eliminated at:
Answer: A constant amount per unit time
Zero-order kinetics means a constant amount of drug is eliminated per unit time regardless of concentration, as seen with ethanol and phenytoin at high doses.