MFDS Pharmacology 2

Question 1

Which property of local anaesthetics determines their potency?

Accepted Answer

Lipid solubility

Answer

Lipid solubility determines the potency of local anaesthetics because a more lipophilic drug penetrates the lipid nerve membrane more readily.

Question 2

The onset of action of a local anaesthetic is primarily determined by its:

Accepted Answer

pKa

Answer

pKa determines onset: drugs with pKa closer to tissue pH (7.4) have a greater proportion in the uncharged (lipid-soluble) form that penetrates nerve membranes, giving faster onset.

Question 3

Adrenaline (epinephrine) is added to local anaesthetic solutions primarily to:

Accepted Answer

Cause vasoconstriction and prolong anaesthesia

Answer

Adrenaline causes local vasoconstriction, reducing vascular uptake and thus prolonging the duration and depth of anaesthesia while reducing systemic absorption.

Question 4

Warfarin anticoagulation should be assessed before dental extractions using:

Accepted Answer

INR

Answer

The INR (International Normalised Ratio) standardises measurement of the prothrombin time and is used to monitor warfarin therapy; dental extractions are generally safe below INR 4.0.

Question 5

Tetracyclines are contraindicated in children under 12 years because they:

Accepted Answer

Bind to calcium in developing teeth causing staining

Answer

Tetracyclines chelate calcium and are deposited in developing mineralised tissues, causing permanent yellow-brown staining and hypoplasia of teeth and bones.

MFDS Part 1 Practice Test

MFDS Part 1 Practice Test

MFDS Pharmacology 2