EDAIC Pharmacokinetics and Pharmacodynamics 4

Question 1

Ketamine's dissociative anesthetic effect is mediated primarily by:

Accepted Answer

Non-competitive NMDA receptor antagonism

Answer

Ketamine produces dissociative anesthesia by non-competitive antagonism of NMDA (N-methyl-D-aspartate) glutamate receptors, blocking the ion channel in an open-channel fashion.

Question 2

The volume of distribution (Vd) of a highly lipophilic drug is characteristically:

Accepted Answer

Much greater than total body water, often >10 L/kg

Answer

Highly lipophilic drugs distribute extensively into fat and tissue, resulting in very large apparent volumes of distribution often many times greater than actual body volume.

Question 3

Zero-order kinetics describes drug elimination where:

Accepted Answer

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

Answer

Zero-order kinetics occurs when elimination pathways are saturated, so a fixed amount (not fraction) of drug is eliminated per unit time, as seen with ethanol and high-dose aspirin.

Question 4

Which property of local anesthetics is most responsible for their ability to cross nerve sheaths and reach the axon membrane?

Accepted Answer

pKa close to physiologic pH allowing significant un-ionized fraction

Answer

Local anesthetics with pKa close to 7.4 have a larger un-ionized (lipid-soluble) fraction at physiologic pH, allowing better membrane penetration to reach the axon.

Question 5

A competitive antagonist shifts the agonist concentration-response curve:

Accepted Answer

To the right in a parallel fashion, without reducing Emax

Answer

A competitive antagonist causes a parallel rightward shift of the agonist dose-response curve (increased EC50) without reducing Emax because its effect is surmountable by excess agonist.

EDAIC - European Diploma in Anesthesiology and Intensive Care Practice Test

EDAIC - European Diploma in Anesthesiology and Intensive Care Practice Test

EDAIC Pharmacokinetics and Pharmacodynamics 4