CARDIO + NEURO: LIDOCAINE

Question 1

LIDOCAINE: INDICATIONS

Answer 1

• 1st choice local anaesthetic in, for example, urinary catheterisation and minor procedures (e.g. suturing).
• Uncommonly, as an antiarrhythmic drug in ventricular tachycardia (VT) and ventricular fibrillation (VF) refractory to electrical cardioversion (although amiodarone is preferred for the latter indication

Question 2

LIDOCAINE: MOA

Answer 2

Enters cells in its uncharged form, accepts a proton and becomes (+)

• Inside cell blocks voltage gated sodium channels and prevents intitation and propagation of action potentials in nerves and muscles -> inducing local anaesthesia
• In the heart, it reduces the duration of the action potential, slows conduction velocity and increases the refractory period. These effects may terminate VT and improve the chances of successfully treating VF.

Question 3

LIDOCAINE: ADVERSE EFFECTS

Answer 3

• Initial stinging sensation
• Drowsiness
• Restless tremor
• Fits
• Hypotension
• Arrhythmias

Question 4

LIDOCAINE: WARNINGS

Answer 4

• Reduce dose in states of reduced cardiac output

Question 5

LIDOCAINE: INTERACTIONS

Answer 5

• Co administrator with a Vasoconstrictor may prolong local anaesthetic effect