Lec 2 Flashcards
Pharmacokinetics of LA is
Uptake
Distribution
Metabolism(biotransformation)
Excretion
All la possess some degree of
All la possess some degree of
Vasoactivity
Ester local anesthetics are potent ___ drugs
Vasodilating
The most potent vasodilator
Procaine
The only anesthetic that consistently produce vasoconstriction
Cocaine
Vasodilation leads to increase in ?
Increase rate of absorption of la in blood
Decreasing duration and depth of anesthesia
Increase chance of overdose
Routes for administration of la
Oral route
Topical route
Injection
Reason for all la absorbed properly?
High first pass metabolism
When you apply topical route on intact skin it’s produces
When you apply topical route on intact skin it’s produces
No anesthetic action
Emla is
Mixture of local anesthetics lidocaine and prilocaine capable of providing surface anesthetics of intact skin
Commonly used route for administration of LA
Injection
Uptake of la after parenteral administration depends on
Vascularity of injection site
Vasoactivity of drug
Iv time (min)
1
Topical time
5
Intrammandar-me
5-10
Subcutaneous time
30 - 90
Brain head liver lungs kidney and spleen have hugh levels of LA due to their
High level of perfusion
____ has the highest level bcos it has the largest mass of tissue in body
Skeletal muscle
Blood level of LA is influenced by
Rate at which drug is absorbed into CVS
Rate of distribution from the vascular compartment to the tissues
Elimination of drug through metabolic or excretory pathways
Elimination half life is the
Rate at which local anesthetic is removed from the blood the time neceassary for 50% reduction in the blood level
All las can cross the
Blood brain barrier and placenta( cannot give prilocaine)
Metabolism is the mechanism by which
Metabolism is the mechanism by which
The body biologically transforms the active drug into one that is pharmacologically inactive
The overall toxicity of a drug depends on a balance between its
Rate of absorption into the blood stream at site of injection and its
Rate of removal from the blood through the processes of tissue uptake and metabolism
Ester metabolized in
Plasma
Amides metabolized in
Liver
Esters la hydrolyzed in plasma by enzyme
Esters la hydrolyzed in plasma by enzyme
Pseudocholinesterase
Slow hydrolysis means
High toxicity
Rate of hydrolysis related to
Rate of hydrolysis related to degree of
Toxicity
Which is hydrolyzed slowest
Which is hydrolyzed slowest
Tetracaine
Chloroprocaine rate of hydrolysis
4.7
Procaine rate of hydrolysis
1.1
Tetracaine rate of hydrolysis
0.3
Ester broken into
Paraaminobenzoic acid and
Dimethyl amino alcohol
Primary site of metabolusm of amide la is
Liver
Prilocaine is metabolized in
Liver and lung its a secondary amine
Rate of metabolism is greatly affected by
Liver function
Hepatic perfusion
Relative contraindication to use of amide La
Significant liver dysfunction or heart failure
Why does articaine has a shorter half life
A portion of its metablusm occurs in ththe blood by plasma cholinesterase
Whats a relative contraindication
Drug in question maybe given to the patient after carefully weighing risks and benefits
Whats an absolute contraindication
Under no circumstance shoulf this drug be administered
Major excretory organs for both LA
Kidneys
Do esters appear in urine
In v small concentrations this is bcos they are almsot hydrolyzed in plasma
Procaine(novocaine) appears in urine as
90% paba and 2% unchanged
10% of cocaine is found unchanged in urine undergoing dialysis bcos
10% of cocaine is found unchanged in urine undergoing dialysis bcos
Unavle to excrete unchanged poryion ot esters or amides
Thus increasing toxicity
