4 Local Anaesthetics Drugs

Question 1

General Side Effect

Answer 1

1) CNS effects: Agitation, confusion, tremors, convulsions, respiratory depression.
2) CV effects: arrhythmia, tachycardia, myocardial depression
(* Counter CV effects i.e. vasodilation by concomitant administration of epinephrine)
3) Hypersensitivity Reactions (rare): metabolism from LA to PABA

Question 2

Local Anaesthetics Overview

Answer 2

Amides: Lignocaine, bupivacaine, prilocaine

Esters: Cocaine, benzocaine, tetracaine

Question 3

Lignocaine

Answer 3

Onset: Rapid

Duration: Medium

Route of Administration: Surface, injection, nerve block, epidural/ spinal

• Never use lignocaine with epinephrine on fingers and toes–> may cut off blood supply

Question 4

Bupivacaine

Answer 4

Onset: Slow

Duration: Long

Route of Administration: Nerve block, epidural/ spinal

• More prone to cardiotoxicity and neurotoxicity

Levo- bupivacaine: less toxic
Ropivacaine: least toxic

Question 5

Cocaine

Answer 5

Onset: Medium

Duration: Medium

Route of Administration: Surface

• Used for nasal intubation and ophthalmic anaesthesia
• Cause euphoria and enhanced sympathetic activity

Question 6

Prilocaine

Answer 6

Onset: Medium

Duration: Medium

• Causes metheglobinemia

Question 7

Tetracaine

Answer 7

Onset: Very slow

Duration: Long

Route of Administration: Surface

• Spinal and corneal anaesthesia

Question 8

Benzocaine

Answer 8

Onset: Slow

Duration: Long

Route of Administration: Surface (dry powder)

• Used to dress painful skin ulcer, throat lozenges, and codom ( delay ejaculation)