Local Anesthetic Pharmacology Flashcards
What are dental theraputics?
Local anesthetic w/ or w/o vasoconstrictors Analgesics Antibiotcs Sedatives and anxiolytics Collagen metabolism modifiers
What are local anesthetics?
Drugs that reversibly block nerve conduction when applied to a local area of the body
Most identified with the suffix- caine
Why is epinephrine added to anesthetics?
Reduced rate of absorption prolongs the effects of anesthesia and lower dosages are required
What was produced to replace cocaine as an anesthetic in 1904?
procaine/”Novocaine” (ester)
What was produced in 1943 as an anesthetic that was more effective with less allergic potential?
Lidocaine (amide)
Remains most frequently used
What is the mechanism of action of local anesthetics?
Block nerve function including pain sensation
Interfere w/ propagation of peripheral nerve impulses
Inhibit generation and conduction of nerve action potential
How do anesthetics interfere with nerve conduction?
They block the influence of stimulation of the membrane on Na ion permeability
A developing local anesthetic block is characterized by a progressive reduction in the rate and extent of depolarization and a slowing of conduction
What is the Specific Receptor Binding Theory on the selective effect of local anesthetics on Na ion permeability?
Local anesthetics stop nerve conduction by binding to specific receptor sites on or within Na+ channels.
Access to this receptor site is from the Intracellular side of the nerve membrane.
Summary of mechanism of action of local anesthetics
Block Na+ flow through the sodium channel
Prevent generation and conduction of nerve action potentials
Act primarily on the internal surface of the cell membrane
Attach to a specific receptor site
What are the three parts of a typical composition of local anesthetic?
Aromatic Group (ring structure) Intermediate chain: ester/amide Amino Group (nitrogen containing)
What is the function of the aromatic group?
Essential for penetration of anatomic barriers btw drug and site of action
LIPOPHILIC
What is the function of the intermediate chain/linkage?
Determines site of metabolism and separates the lipophilic from the hydrophilic portions
What is the function of the amino group?
Ensures the drug will not precipitate in interstitial fluid
HYDROPHILIC
Characteristics of ester anesthetics
High allergenicity potential
Metabolized in bloodstream by plasma cholinesterases
Generally poor diffusion properties
Include: cocaine, procaine, tetracaine, propoxycaine
Why is Novocaine (procaine) rarely used anymore?
High allergenicity
Short duration: requires vasoconstrictor
Poor efficacy and profundity
