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91 Cards in this Set

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Natural alkaloid and only natural compound remaining?
cocaine
first LA discovered?
cocaine
LA acid/base character?
weak bases
LA's are prepared as?
HCL salts
Also can be Formulated at pH 4.4 – 6.4 if have epinephrine because?
epinephrine more stable at acidic pH.
When injected, LA's are converted to more ________ form.
non-ionized
amine LA Pka?
Pka 7.6 to 9.1 (classic amine pka)
What is the advantage of formulation in bicarbonate solution?
more non-ionized
________ pKa's are most ionized?
highest
Amides formulated with a _________ which may cause an allergic reaction
preservative
________ derivatives used for amide LA preservatives.
paraben
If parabens used, cannot use formulation for ____________ because they are neurotoxic.
spinal/epidural/IV regional
the amine provides _______ phobic character?
hydrophillic
the benzene ring provides _______ phobic character?
lipophillic
If inject LA's into area of local infection (these areas are acidotic) then will have ____ absorption/distribution and ______ onset.
poor

slower
LA lipid solubility effect on potency?
increased
the larger number of carbons, the more _________?
lipophillic
increased potency with a ______ on the aromatic ring?
halide
increased potency with a ______ and ______ on the terminal amine?
ester linkage

large alkyl group
How does ionization contribute to efficacy?
more lipophylic more potent
How does ionization contribute to Absorption?
more non-ionized better absorption into tissues
How does ionization contribute to Distribution?
more lipophylic/less ionized less distribution away from site
How does ionization contribute to Duration of action?
more ionized, less distributed/absorbed)

more lipophylic longer duration (result of less distribution)
Lidocaine (Xylocaine)

pKa % non-ionized
7.9
25
Bupivicaine (Marcaine)

pKa % non-ionized
8.1
15
Cocaine

pKa % non-ionized
8.7
5
Procaine

pKa % non-ionized
8.9
3
Chloroprocaine (Nesacaine)

pKa % non-ionized
8.7
5
Tetracaine (Pontocaine)

pKa % non-ionized
8.5
7
Etidocaine (Duranest)

pKa % non-ionized
7.7 33
Mepivacaine(Carbocaine)

pKa % non-ionized
7.6
37%
Cocaine is the ester of ?
benzoic acid
Ester Analogs [4]
Cocaine
Procaine
Tetracaine
Chloroprocaine
Amide Analogs [6]
Prilocaine
Lidocaine
Mepivacaine
Bupivicaine
Etidocaine
Ropivacaine
Most Potent (also most toxic) [4]
Tetracaine (ester, pKa 8.2)
Etidocaine (amide, pKa 7.7)
Bupivicaine (amide, pKa 8.1)
Ropivicaine (amide, pKa 8.1
lesser (middle) potency LA's [4]
Lidocaine (amide, pKa 7.8)
Mepivacaine (amide, pKa 7.6
Prilocaine (amide, pKa 7.8)
Cocaine (ester, pKa 8.7)
least potent LA's [2]
Chloroprocaine (ester, pKa 9.0)
Procaine (ester, pKa 8.9)
LA potency rated by?
minimum blocking concentration (Cm) is the lowest concentration that blocks conduction
Potency determined in large part by?
lipid solubility (like most compounds)
topical use LA's? [3]
tetracaine, lidocaine, cocaine.
uses for LA's? [6]
Surgery
Dentistry
Acute Pain
Chronic Pain
Punctures
Endoscopic Procedures
Local anesthetics prevent voltage-gated fast sodium channels in nerve axons from _________... Bind to sodium channels inside the neruon when they are in the inactivated state.
opening
__________ form crosses the lipid bilayer to enter neuron and the _________ form binds to the gated sodium channel
unionized

ionized
Sodium channel has three states?
closed/open/inactivated
The voltage sensor senses change in _________ due to nerve stimulation
voltage
Local anesthetic passes through lipid bi-layer in _________ form and then ionized form (cation) binds within the pore blocking the pore.
non-ionized
LA's are more selective for nerves without ________?
myelination – but still will get some sensory inhibition (ok and wanted) and some motor inhibiton (maybe don’t necissarily want)
LA's are most specific for what nerve fibers?
Most specific for B and C and some alpha delta fibers.
LA's are specific for? [3]
Chanel state
channels that are in depolarized (open) state.
Axonal Diameter
small
Degree of myelination
Minor
Autonomic>sensory>motor
Other Receptor InteractionS? [2]
NMDA
Calcium and Potassium Channels
Other drugs that work at the Sodium Channel?
Tricylic Antidepressants
Meperidine
Volatile Anesthetics
Ketamine
Tetrodotoxin
factors that affet LA absorption> [7]
Delivery Method
Dose
Tissue Blood flow
Lipid Solubility
Protein Binding
pH
Vasoconstriction
tissue blood flow....

we don't want for local use.
vascularity intravenous>tracheal>intercostal>cadal>paracervical>epidural?brachial plexus>sciatic>subcutaneous
The higher the pH the ____ absorbed .
less

mostly an issue for inflammation. Inflammation causes and acidotic state. More drug in ionized form and less absorption. Also can see tachyphylaxis (decreased efficacy of repeated doses) because the acidic formulation makes the area more acidic
factors that affet LA Distribution [4]
Lipophilicity
Blood Flow
intravenous>tracheal>intercostal>cadal>paracervical>epidural>brachial plexus>sciatic>subcutaneous
Tissue Perfusion
Protein Binding
So more lipid soluble, the _____ movement and ____ stays at the site.
less

more

More lipid soluble will stay in the tissues and not be distributed and this helps contribute to potency.
The ________ the metabolism and elimination, the more possibility for toxicity
slower
Ester Metabolism?
Chloroprocaine>>procaine>tetracaine
Amide Metabolism
Prilocaine>lidocaine>mepivicaine>ropivicaine>bupivicaine
Lidocaine specific toxicity
Prilocaine specific toxicity
Benzocaine specific toxicity
PABA metabolite>
esters
esters biotransformed by
plasma pseudocholinesterase.
Chloro eliminated faster because
hydrolysis 3.5 times faster than pro so least toxic
Cocaine metabolization
Differently than all other esters because metabolized in the Liver (more unchanged excreted)
PABA allergy?
with esters

Cause local edema- urticaria – bronchospasm - anaphylaxis
Amides eliminated by?
liver metabolism (dealkyl, hydroxylation)
any drug that interferes with liver metabolism will cause _______ toxicity?
amide
Decrease in hepatic blood flow with cause ______ toxicity?

causes?
amide toxicity

(congestive heart failure, vasopressors, H2 receptor blockers, volatile anesthetics, propranolol, cimetidine)
Lidocaine is metabolized to?
monoethylglycinexylidide which is active and can contribute to toxicity. (elimination does not parallel duration). Lidocaine may be within TI but if metabolite isn’t accounted for, will see toxicity (this can be an issue with repeated dosing)
methhemoglobin issue with?
Benzocaine
Prilocaine
Prilocaine metabolism?
o-toluidine analogs can accumulate and convert hemoglobin to methemoglobin (oxidation-reduction reaction-of iron) so interfere with oxygen transport (can be issue in baby after epidural use during labor)
Methhemoglobin treated with
methylene blue to reduced iron III to iron II.(reduction) OIL-RIG we are going from 3+ to 2+
the toxicant are _______?
The toxants are oxidants, they take fe2+ to fe3+
LA with longest t1/2?
Bupivicaine (one of the most potent) has longest halftime for elimination
Elimination of LA'S?
Protein Binding
Mostly Urinary elimination
LA S/A's?
Excitatory
Dermal
Blanching, edema, etc.
Neurological
Cardiovascular
Blockade of sodium channels
Inhibit autonomic nervous system
Neurological
Respiratory
Immulogical
Musculoskeletal
Hematological
first S/A's seen?
Neurological
See this first
They can be nuerotoxic
Cirumoral numbness, tongue paresthesia, diziness, restlessness, aginitation complaints of tinnitus blurred vision
Muscle twitching shows headed into tonic-clonic seizures -Etido can cause at lower serum concentrations than the others
can reduces CBF and hyperventilate can mediate (benzodiazepines, thipental 1-2 mg/kg quickly terminates seizure)
Lidocaine – decreases CBF which attenuates ICP that sometimes see with intubation
most cardiotoxic?
Bupivicaine is most cardiotoxic because It is highly lipid soluble and only slowly dissociates from sodium channels so more blockade. This exaggerates the depressive effects and is also persistent
Cardiovascular S/A's?
depress myocardial automaticity (phase 4 depolarization) and reduce duration of refractory period. Depress contractility and conduction velocity at higher concentrations. Relax smooth muscle so vasodilatation except cocaine which is a vasoconstrictor.
Bradychardia/heart block/vasodilatation can lead to cardiac arrest. But usually this is at levels higher than used and would actually see seizures first. Signs of toxicity may be CNS excitement (tachycardia and hypertension)
Bupivicaine>Etidocaine> Ropivicainepi (ropi also less motor blockade good for obstetric patients)
resp S/A's?
Lidocaine depresses hypoxic drive (apnea), can cause bronchospasm is used in spray, may be effective in blocking the bronchoconstriction after intubation
Relax bronchial smooth muscle
immunological s/a's
Allergies from PABA from ester hydrolysis and allergies from methylparaben sometimes used to formulate amides
musculoskeletal s/a's
Myotoxic if injected into muscle (bupi>lido>pro)
hemotalogical s/a's
Lidocaine can decrease coagulation and enhances fibrinolysis
Etido and bupi lowest max dose
Subcu etido is _ as toxic as subcu bupi
contraindications? [4]
Atypical Plasma pseudocholinesterase
Allergies
Cardiac Drugs
Drug-drug interactions
what LA can you give to a patient with atypical/depressed plasma cholinesterase?
cocaine (liver metab)
Avoid drugs to minimize cardiac toxicity
Beta-adrenergic blockers (labetalol, propranol)
Digitalis
Calcium channel blockers (verapamil)
These drugs inhibit impulse propagation and may decrease the threshold for cardiac toxicity especially if the cardiotoxin bupivicaine is used.
Drug-drug interactions competing for pseudocholinesterases ?
(succinylcholine)
Opioids and alpha-adrenergic agonists_______ the pain relief of local anesthetics
enhance
Epidural chloroprocaine may _________ with intraspinal morphine analgesia (less anlagesia)
interfere
Anticholinesterases [4]
Echothiophate (irreversible)
Neostigmine (reversible)
Pyridostigmine (reversible)
Edrophonium (reversible)

Inhibit the acetylcholinesterases prolonging activity (with esthers)
irreversible Anticholinesterase?
Echothiophate
epi effect on LA's
less (slower) distribution