Local Anesthetics are classified by their linkage what are the 2 classes
Esters and Amides
List 4 esters
Chloroprocaine, Procaine, cocaine, tetracaine
List 5 Amides
Lidocaine, Mepivicaine, Bupivicaine, Prilocaine, Ropivicaine
Name 4 short acting Locals
Procaine, Chloroprocaine, Lidocaine, Tetracaine
Name 3 longer acting Locals
Mepivacaine, Bupivicaine, Ropivicaine
Local anesthetics MOA
Na+ inhibition the the Na+ Ion channels
Which portion of the drug crosses the membrane?
pKa equated to what - potency, onset, or duration?
Lipid solubility equates to what- potency, onset, or duration?
Protein binding equates to what - potency, onset, or duration?
max dose of Lidocaine and Mepivacaine per Kg with and without Epi
4.5 mg/kg without and 7 mg/kg with epi
Max dose of Bupivacaine or Ropivacaine with and without epi?
2.8 mg/kg without and 3.2mg/kg with epi
Max toxic dose for Lidocaine and Mepivacaine without epi
Max toxic dose for Lidocaine and Mepivacaine with epi
Max dose of Bupivacaine and Ropivacaine without epi
Max dose of Bupivacaine and Ropivacaine with epi
Which Locals have a fast onset or closer to physiologic Ph? There is one exception to this?
Lidocaine pKa 7.7 Mepivacaine pKa 7.6 Chloroprocaine Pka 9.1 (THE EXCEPTION)
Which Locals have a slower onset or are further away from physiologic Ph?
Procaine pKa 8.9 Tetracaine pKa 8.6
Which Locals have a moderate onset?
Bupivacaine pKa 8.1 Ropivacaine pKa 8.1
Know this Chem formula
Absorption is influenced by?
Dosage, site of injuection, Vasoconstriction, and Pharmacologic properties
When the vessel is in the nerve bundle will you have ? Increased or Decreased uptake of the LA?
Cocaine causes vasocontstiction by affecting ?
Dopaimine and norepinephrine decreasing reuptake
Will epi extend short acting or longer acting LA for a longer time period?
It will extend longer acting LA for a longer time period because Longer acting LA are more Lipophilic which is directly related to durration
Amides have a wider distribution because
Increased storage in the tissues because of rapid uptake of highly perfused tissues like the the brain, liver kidneys and heart and a slower uptake from the moderately perfused tissues lik the gut and muscles
LONG ANSWER IT SUCKS
Esters have a shorter duration because
They are broken down by plasma esterase
Which Locals are best for stat C Sections?
Chloroprocaine and procaine
Because they are ESTERS it get hydrolized in < 1 min
LA are excreated in what form Ionized or Nonionized
Nonioinzed - the renal tubules do not reabsorb charged metabolites
MOA of LA
Mechanism of Action:
1. Diffusion of the base form across the across the nerve sheath and nerve membrane 2. Re-equilibration between the base and cationic forms in the axoplasm
3. Penetration of the cation into and attachment to a receptor site within the sodium channel.
4. Blockade of the sodium channel
5. Inhibition of sodium conduction
6. Decrease in the rate and degree of the depolarization phase of the action potential
7. Failure to achieve the threshold potential
8. Lack of development of a propagated action potential
9. Blockade of impulse conduction
La block conduction in the following order?
Small myelinated axons
non myelinated axons
Large myelinated axons