local anesthetics Flashcards
MOA of LA?
- block sodium channels in axonal membrane
- use dependency where the depth of LA nerve block increases with action potential frequency as LA molecules
- non-selective modifiers of neuronal function
factors affecting LA action
- lipid solubility - higher solubility
- size of nerves - smaller > bigger
- higher frequency of neuron firing
- circumferential position > deeper position
- myelinated > non-myelinated
- pH dependence - low ionization better
what are the two types of LA
list some examples
ester type (procaine) and amide type (lidocaine)
how to prevent systemic distribution of LA
combine with epinephrine
list some of the CNS effects of LA
sleepiness, visual and auditory effects, restlessness, nystagmus, shivering, convulsion, stoppage of vital function, death
what are some CVD effects of LA
cardiac contraction, arteriolar dilation and HoTN, cardiovascular collapse
which is the most cardiotoxic LA?
bupivacaine
what is the ADR specific to cocaine
blocks NA reuptake, increase NA at the synapse which causes vasoconstriction & HTN
prilocaine is metabolised to ______ which can cause _______. this can be reversed by ________.
O-tuluidine, methemoglobin, IV methyleneblue/ascorbic acid
what is a disadvantage of ester LA
can be hydrolyzed to PABA which causes allergic reactions in small percentages of the population
list some of the clinical applications of LAs
- surface: skin, eye, otorhinolaryngology
- infiltration
- nerve block: lose peripheral sensation
- epidural: spinal anesthesia
what are the ideal characteristics of surface analgesias
rapid penetration of skin and limited tendency to diffuse away
what are some examples of surface anesthetics
lidocaine, tetracaine, benzocaine
what are some examples of epidural anesthetics
lidocaine and bupivacaine
