000 - Local Anesthetics Flashcards
Local anesthetics are weak acids or weak bases?
weak bases
Because local anesthetics are weak bases, they are marketed as what kind of salt?
HCl
Chemically, local anesthetics are either of what two types of compounds?
esters and amides
procaine is metabolized in…
blood
procaine metabolized in the blood is metabolized by what enyzme?
pseudocholinesterase
lidocaine is metabolized in the…
liver
which is metabolized faster; procaine or lidocaine?
procaine
The dose of LA required to anesthetize necrotic tissue is larger or smaller than normal
why?
larger
cause low pH
At low pH, local anesthetics are more or less ionized?
more
local anesthetics cross the nerves best when more or less ionized?
less
Nerves are more sensitive to local anesthetics when they are active or inactive?
when they are active. there is more of a sodium flux of ions through the channels, so more opportunity for drugs to gain admittance
Small or large nerve fibers are more sensitive to local anesthetics?
small c fibers (virtually no myelination)
Local anesthesia is prolonged by what drugs?
symphathomimetics and vasoconstrictors (keeps local blood flow low so that drug in not washed out)
What is the local anesthetic effect on the CV system
decreased BP, HR, TPR
benzocaine has a high or low solubility?
low
