MJDF Pharmacology & Pain Control

Question 1

What is the mechanism of action of lidocaine as a local anaesthetic?

Accepted Answer

Blocks voltage-gated sodium channels, preventing action potential propagation in nerve fibres

Answer

Blocks potassium channels

Answer

Inhibits calcium influx at the neuromuscular junction

Answer

Activates GABA receptors

Question 2

Why does local anaesthesia work less effectively in infected tissue?

Accepted Answer

Acidic pH in infected tissue increases ionisation of LA, reducing membrane penetration

Answer

Bacteria directly inactivate the LA

Answer

Increased blood flow washes away the LA immediately

Answer

Infected tissue has fewer nerve endings

Question 3

What is the maximum safe dose of articaine with adrenaline for a 70 kg adult?

Accepted Answer

7 mg/kg (approximately 490 mg — about 5–6 cartridges of 4% articaine)

Answer

3.5 mg/kg

Answer

10 mg/kg

Answer

1.5 mg/kg

Question 4

What is the pharmacological reason for adding adrenaline to a local anaesthetic?

Accepted Answer

Causes local vasoconstriction, reducing systemic absorption, prolonging duration, and improving depth of anaesthesia

Answer

Acts as a second anaesthetic

Answer

Increases pH of the solution

Answer

Prevents bacterial contamination

Question 5

Which group of patients requires special caution when administering adrenaline-containing local anaesthetic?

Accepted Answer

Patients taking non-selective beta-blockers (risk of hypertensive crisis)

Answer

Patients taking ACE inhibitors

Answer

Patients with well-controlled Type 2 diabetes

Answer

Patients taking statins

Question 6

What is the appropriate management of an intravascular injection of local anaesthetic?

Accepted Answer

Stop injection immediately, monitor vital signs, position supine, call 999 if systemic signs develop

Answer

Continue injection at a slower rate

Answer

Administer atropine

Answer

Give more LA to reverse the effect