Flashcards in Katzung 12th ed - Chapter 26 - Local Anaesthetics (1) Deck (22):
What is an easy way to remember which local anaesthetics are amides and which are esters?
Amides have two i's in their name:
e.g. Lignocaine, Mepivacaine, Bupivacaine, Ropivacaine, Prilocaine
Esters have only one i in their name:
e.g. Cocaine, Procaine, Tetracaine.
What is Xylocaine?
Xylocaine is the trade name for Lignocaine.
What is Marcaine?
Marcaine is the trade name for Bupivacaine.
Which local anaesthetic has the lowest potency?
Which local anaesthetic has the shortest duration of action?
Name three local anaesthetics with long durations of action.
Tetracaine, Bupivacaine, Ropivacaine.
Describe the pharmacokinetics of ester-based local anaesthetics.
They have a rapid breakdown in plasma (elimination half-life is less than 1 minute) and thus have not been extensively studied.
Pharmacokinetics of amide LA's: Absorption. Describe how the administration of an amide LA together with adrenaline would affect the absorption.
Adrenaline is a vasoconstrictor, and therefore the resultant reduction in blood flow serves to reduce the rate of systemic absorption of amide LA and thus diminishes peak serum levels.
How could ester-based local anaesthetics potentially accumulate in the bloodstream of a patient?
If the patient has reduced or absent plasma hydrolysis secondary to plasma cholinesterase deficiency.
Where are the amide local anaesthetics metabolised?
Which amide local anaesthetic is the most rapidly metabolised?
What are the approximate elimination half-lives of bupivacaine and ropivacaine?
They both have relatively slow hepatic metabolism.
Pharmacodynamics: What is the primary mechanism of action of local anaesthetics?
Voltage-gated Sodium channel blockade.
If Procaine has a potency of "1", what is the potency of:
- Bupivacaine: 16
- Lignocaine: 4
- Cocaine: 2
What is a safe dose of lignocaine if given:
- S/C with adrenaline?
- IV: 2mg/kg
- S/C: 3mg/kg
- S/C with adrenaline: 5mg/kg
What is a safe dose of S/C bupivacaine?
What is a safe dose of intravenous regional anaesthesia (Bier's block) using Prilocaine?
Name four potential clinical uses for local anaesthetics.
Intravenous regional anaesthesia (Bier's block)
Describe some CNS toxicities of local anaesthetics.
Drowsiness, Visual and Auditory disturbances, Restlessness, Nystagmus, Shivering, Convulsions
How do potassium levels affect the actions of local anaesthetics?
Hyperkalaemia will increase the effects of local anaesthetics.
Describe some CVS toxicities of local anaesthetics.
Negative Inotrope. Decreased PVR. Reduced excitability and conduction.