Local anasthetic agents Flashcards
Which form of LA enters the cell
LA, uncharged
MOA of LA
Reversibly blocks open Na+ channels from within the cell. Must enter the cell (LA) and become ionized (LA+) to bind.
Order of nerve block for LAs
Pain fibers first
sensation fibers next
motor function blocked last
What is potency correlated with for LAs
lipid solubility, more lipid soluble = more potent
Size, smaller size = more potent
Effect of vasoconstriction in LA
reduce systemic absorpion. If drug does not have vasoconstriction properties, may add epinephrine
metabolism of LAs
Amide LAs metabolized in the liver by CYP P450
Ester LAs metabolized in plasmas by plasma cholinesterase
Factors affecting clearance of LAs (4)
Patient age
Liver function
Cardiovascular function
Type of LA, esters degraded faster
Systemic toxicity of LAs
Hypersensitivity of metabolites of Ester LAs
Hypersensitivity to methylparaben preservative
CNS toxicity of LAs
sedation lightheadedness visual and auditory disturbances tounge numbness and metalic taste muscular twitching, nystagmus, and convulsions
Cardiovascular toxicity of LAs
Most feared toxicity, affect conduction (bupivicaine)
IV infusion of lipid can treat cardiotoxicity
