Pharmacology Flashcards
6 cards from real MFDS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Pharmacology flashcards as text
Which property of local anaesthetics determines their potency?
Answer: Lipid solubility
Lipid solubility determines the potency of local anaesthetics because a more lipophilic drug penetrates the lipid nerve membrane more readily.
The onset of action of a local anaesthetic is primarily determined by its:
Answer: pKa
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.
Adrenaline (epinephrine) is added to local anaesthetic solutions primarily to:
Answer: Cause vasoconstriction and prolong anaesthesia
Adrenaline causes local vasoconstriction, reducing vascular uptake and thus prolonging the duration and depth of anaesthesia while reducing systemic absorption.
Warfarin anticoagulation should be assessed before dental extractions using:
Answer: INR
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.
Tetracyclines are contraindicated in children under 12 years because they:
Answer: Bind to calcium in developing teeth causing staining
Tetracyclines chelate calcium and are deposited in developing mineralised tissues, causing permanent yellow-brown staining and hypoplasia of teeth and bones.
Which drug interaction is most clinically significant when prescribing metronidazole?
Answer: Alcohol (disulfiram-like reaction)
Metronidazole inhibits aldehyde dehydrogenase, causing accumulation of acetaldehyde when alcohol is consumed, producing a severe disulfiram-like reaction.