Pharmacology
Local Anaesthetics
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Get access- Consist of an aromatic residue linked to an amide side chain
- Inactivated in the liver and plasma
- Block action potentials initiation and propagation
- Act on sodium channels
- Prevent voltage-dependent increase in sodium conductance
- Action is pH dependent
- They are weak bases so are better instilled as an alkaline solution
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Inflamed tissue is acidic and so local anaesthetic penetration will be reduced
For infiltrative local anaesthesia, a 1:200,000 concentration of adrenaline is added to constrict blood vessels and reduce vascular absorption
- Adrenaline is inactivated by heat
Topical local anaesthetics impair wound healing: disrupt tight junctions between cells and interfere with corneal epithelial metabolism