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
A patient's creatinine clearance (CrCl) decreases from 100 to 50 mL/min. How should the dose of a renally eliminated drug be adjusted?
Answer: Reduce the dose by 50% or double the interval
When CrCl is halved, the drug's renal clearance is also approximately halved, so the dose should be reduced by 50% or the dosing interval doubled to maintain target exposure.
What does the term 'agonist' mean in pharmacodynamics?
Answer: A drug that binds and activates a receptor to produce a response
An agonist binds to a receptor and activates it, mimicking the endogenous ligand and producing a pharmacological response.
Which parameter reflects the concentration of drug that produces 50% of the maximum effect?
Answer: EC50
EC50 (effective concentration 50%) is the drug concentration that produces 50% of the maximum pharmacological effect and is a measure of drug potency.
Hepatic extraction ratio (ER) greater than 0.7 indicates:
Answer: High first-pass metabolism
A hepatic extraction ratio greater than 0.7 indicates high first-pass metabolism, meaning more than 70% of the drug is extracted by the liver on first pass.
Which of the following is a clinical sign of drug toxicity due to accumulation in a patient with renal failure?
Answer: Increased drug half-life and elevated plasma concentrations
Renal failure impairs drug elimination, leading to increased half-life and drug accumulation with elevated plasma concentrations, raising toxicity risk.
Which pharmacokinetic process is described by the Henderson-Hasselbalch equation as it applies to drugs?
Answer: Ionization of weak acids and bases affecting membrane permeability
The Henderson-Hasselbalch equation predicts the degree of ionization of weak acid or base drugs based on pKa and pH, which directly affects lipid solubility and membrane permeability.