Local Anesthetics Flashcards
LA consists of a ______ & ______ portion separated by a connecting hydrocarbon chain.
Lipophilic; hydrophilic
LA are poorly soluble in water and are marketed as water soluble _____________
Hydrochloride salts
These hydrochloride salt solutions contribute to the ________ of the LA
Stability
Substituting a butyl group for the amine group on the benzene ring of procaine results in?
Tetracaine
Compared to procaine, tetracaine is more ____________. _____ times more potent, and has a _______________ duration corresponding to a _______ fold decrease rate of metabolism
Lipid soluble;
10 x;
Longer duration;
4 -5
The ________ of bupivacaine and Mepivacaine appear to be less toxic than the commercially available racemic mixtures of the LA.
S enantiomers
The S enantiomers are considered to produce less ________ & _______ than racemic mixtures or the R enantiomers of LA
Neurotoxicity; cardiotoxicity
What 2 LA are available for clinical use as racemic mixtures (50:50) of the enantiomers?
Mepivacaine & Bupivacaine
What 4 LA are chiral drugs that may have S or R configurations?
Mepivacaine, Bupivacaine, Ropivacaine, & Levobupivacaine
Halogenation of procaine to chloroprocaine results in ___________ increase in hydrolysis rate of chloroprocaine by ______________
3-4 fold; plasma cholinesterase
Etidocaine resembles lidocaine but has a _____ increase in lipid solubility and 2-3 fold increase in ________.
50 fold; duration of action
________ is 35 times more lipid soluble and has a potency and duration of action ____ times that of Mepivacaine
Bupivacaine; 3-4
Drugs such as _______, _______, & _______ have been incorporated into liposomes to prolong the duration of action and decrease toxicity
Lidocaine, tetracaine, bupivacaine
Bupivacaine extended release liposome injection has been approved by the FDA for local infiltration of anesthesia and for _______
Hemorrhoidectomy and bunionectomy
LA binds to specific sites in ____________ channels
Voltage gated Na
LA blocks ______ current reducing excitability of _____, ______, or ______ tissue
Na ion; neuronal, cardiac, CNS
LA prevents transmission of nerve impulses (conduction blockade) by inhibition passage of __________________ in nerve membranes
Na ions through ion-selective Na channels
A specific receptor for LA molecules
Na channel
Describe how action potential is not propagated d/t Na ion channel
Failure of Na ion channel permeability to increase slows rate of depolarization such that the threshold potential is not reached, and the AP is not propagated (LA do NOT alter the resting membrane potential or threshold potential)
Increased sensitivity _________________ may be present during pregnancy
(More rapid onset of conduction blockade)
Name 3 esters from table 10-1
Procaine, Chloroprocaine, & tetracaine
Name 2 rapid onset LA from table 10-1
Chloroprocaine, Lidocaine
Which LA has the greatest protein binding
Levobupivacaine
LA are weak ______
Bases
