Local Anesthetics Flashcards
type of molecules are local anesthetics
weak bases
most active form of local anesthetics at the receptor site and the most penetrable form
most active - cationic form
rapid penetrability - uncharged form
why are local anesthetics less effective in infected tissue
they have low pH so very low fraction of non ionized local anesthetics is available for diffusion in the cell
drug that works by constricting BV by potentiating the action of NE hence preventing its absorption
cocaine
why do local anesthetics contain a constrictor like epinephrine
-reduces system absorption of local anesthetics from the depot site by decreasing blow flow in these areas –> neuronal uptake of drug is enhanced due to higher local drug concentration and system toxic effects are reduced
how does epinephrine work in spinal anesthesia
acts on alpha 2 receptors –> inhibits release of substance P –> reduces sensory neuron firing
mechanism of local anesthetics
block voltage gated sodium channels
relationship between liposolubility with potency and toxicity
the more liposolube, the more potent and the more toxic
relationship between pKa and onset of action
the closer the pKa to body pH, the faster the onset
what are the ester local anesthetic
Cocaine
Procaine
Tetracaine
Benzocaine
what are the amide local anesthetic
Lidocaine
Bupivacaine
Prilocaine
Ropivacaine
provides prophylaxis against seizures when large doses of local anesthetic must be given
diazepam
how does local anesthetics affect cardiovascular system …mention exceptions
- block Na channels –> depress cardiac pacemaker activity, excitability, and conduction
- if really high conc, can block Ca channels
- with exception to cocaine, depress cardiac contraction and cause arteriolar dilation –> hypotension
what are ways cocaine differ from the other local anesthetics in ways it affects the CVS
- blocks NE uptake –> vasoconstriction and hypertension
- vasoconstriction –> ischemia
the most cardiotoxic local anesthetic
Bupivacaine
