Local anesthetics are either esters (procaine, dibucaine, benzocaine, etc) or amides (lidocaine, prilocaine, bupivacaine, etc). The ester containing compounds are usually inactivated in the plasma and tissues by non-specific esterases. Local anesthetics block the initiation of action potentials by preventing the voltage-dependant increase in Na+ conductance.
Local anesthetics are used in minor surgery, dentistry, abdominal surgery and painless childbirth. The unwanted effects are due the enterance of LA into systemic circulation and these are: CNS effects (agitation, confusion, respiratory depression, and convulsion), CVS effects (myocardial depression, hypotension) and occasional hypersensitivity reactions.
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