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FINALS LOCAL ANESTHETIC AGENT EXAM 2025-2026|
QUESTIONS WITH CORRECT ANSWERS|100% PASS
- To temporarily interrupt pain conduction in a nerve FINALS LOCAL ANESTHETIC AGENT function Cocaine
- Past parent drug; vasoconstrictor; CNS stimulant; schedule I drug Cocaine
- No longer used as a parent drug (a lot of negative effects like high addiction potential) Cocaine
- Retained "caine" as a tribute but don't have chemical structure of cocaine
Cocaine
- LAA are drugs used to control pain; if not to totally eliminate pain, to control your dental patients Difference of anesthetics to analgesics LAA temporarily disrupt the impulse of the nerve where the LAA is injected -> Anesthetic molecules block the Ca ion channels which the sodium ions take when it goes in and out of the nerve. If those Ca ions are blocked, transmission of impulse is disrupted Non-narcotic analgesics inhibiting the synthesis of prostaglandins Difference of anesthetics to analgesics Difference of anesthetics to analgesics Difference of anesthetics to analgesics
- Onset of action: LAA faster, orally slower
- Took over procaine as the most popular local anesthetic Ester
- First came out
- High incidence of allergic reaction Ester and Amide has one common property ability to produce vasodilation in peripheral blood vessels; inherent property Anesthetic effect the numbness is profound, and that numbness stays in that area for as long as the drug molecules remains in that tissues, but since LA causes dilation of blood vessels the rate of absorption in to the bloodstream is increased, causing the numbness to shorten; if there's rapid uptake of LA agent's molecules into the blood stream, that can lead to toxicity; In order to offset this, to cancel this out/the vasodilating effect, majority of LA agent is available in a solution that contains vasoconstrictor
Articane is classified as an amide but it contains some chemical structures of ester Procaine Most potent vasodilator cocaine Local Anesthetic Agent that has no vasodilating properties Poorly absorbed by the GIT (Not given orally) -> Reason why it is injected Because it is local, it is supposed to take effect in a specific area of the body Undergo first pass effect (approximately 72%) o i.e. Lidocaine -> large portion of drug becomes in active, pass, metabolized, then excreted
clinically induce the vasodilation when peripheral blood flow is compromised due to accidental LA injection of a drug i.e. Thiopental/Epinephrine in the blood supply of a limb (Exception -> Mepivacaine) IV administered: Only for treatment of ventricular dysrhythmias (ie PVC) Thiopental -> Procaine Barbiturate; ultrashort (mins); youll become groggy; truth serum causes arterial spasms; use procaine if accidentally you injected thiopental in your finger, inject procaine because it is a vasodilator Procaine, Lidocaine in mucus membrane only but not in intact skin
Procaine: brand name is novocaine; brand name is ____ , is the most potent vasodilator Once absorbed into the circulation wide distribution; i.e. skeletal muscles Ester type While still in the blood, metabolized by enzyme cholinesterase Gradual decrease in anesthetic effect - Rate of anesthetic effect when Delivered to the tissues either for storage, or organs (liver) for metabolism
- Absorption rate into the circulation
- Fast absorption rate
- Procaine without a vasoconstrictor
liver -> Liver disease/problems will affect the dosage of LAA to the patient or might have to totally avoid Excretion - Renal - kidney disease is a relative contraindication-> Main route hydrolysis by plasma (pseudo)cholinesterase enzyme Biotransformation: Ester liver -> Liver disease/problems will affect the dosage of LAA to the patient or might have to totally avoid Excretion - Renal - kidney disease is a relative contraindication-> Main route Biotransformation: Amide Renal excretion of drug 3 Mechanism GAP
- Glomerular Filtration
- Active Tubular Secretion
- Passive Tubular Reabsorption
- Reversible Action
- Anesthetic effect should be temporary
- Non-irritating to tissues and produce no secondary local reactions (pain necrosis)
- Every now and then, LAA may still cause secondary local reaction in idiocyncratic patients or something different with patient that may cause the secondary reaction
- Low degree of systemic toxicity
- Stick of correct dosage and avoid intravascular injection
- Potency: strength of a drug, directly proportional to produce toxicity, mg amount of a drug that is needed to produce an effect?, indirectly proportional to dose
- LAA right amount of potencyas long as they are not absorbed in a very fast rate
- Rapid onset and of sufficient duration of effect
- Makes drug practical
- One cartridge by blocking technique can last 1-1.5 hours
- Potent enough without the use of very high concentrations
- More potent, higher risk of toxicity'/potency inversely proportional to dosa Properties of an Ideal Local Anesthetic Agent
- Mepivacaine (Carbocaine, mepivastesin, polocaine, scandonest)
- Bupivacaine (sensorcaine, Mercaine)
- Articaine ( zarcaine, septocaine, primacaine)
- Dibucaine
- Etidocaine
- Ropivacain Note: 6-8 are not used as dental LA
- Lidocaine (Xylocaine)
- Prilocaine (Citanest)
- Mepivacaine (carbocaine, mepivastesin, polocaine, scandonest)
- Bupivacaine ( sensorcaine, mercaine)
- Articaine ( zarcaine, septocaine, primacaine)
- Dibucaine
- Etidocaine
- Ropivacain State the Amides Esters Greater potential of producing hypersensitivy reactions: esters or amides? Esters classification B. Benzoic Acid
Common Properties of LA agents currently in use
- All are synthetic
- All contain amino group
- All form salts with strong acids
- The salts are water soluble - diffuse into tissues
- Alkali increases the concentration of unionized free base
- The unionized free base is lipid soluble - can pass through the membrane
- Salts are acid in reaction and relatively stable (extends its shelf life)
- Either undergoes hydrolysis by plasma cholinesterase (Ester) or biotransformation in liver (amides) -> Hepatic microsomal enzyme system
- Actions are reversible
- All are compatible with vasoconstrictors
- All are incompatible with metal salts of Hg, Ag, etc
- All affect nerve conduction in a similar manner
- All are capable of being toxic in high plasma concentrations
- All have a little or no irritating effects in anesthetic doses
Drug must be lipid soluble to be able to penetrate the membrane of the nerve (i.e. myelin sheath) to be able to temporarily disrupt the impulse Why must a Drug must be lipid soluble? Drug must be ___ water soluble and lipid soluble (balanced) Partially Mainly composed of a weak base and a strong acid Mainly composed of a___ base and a ____ acid Have both lipophilic (lipid solubility) and hydrophilic (water solubility) properties Have both _____ solubility) and____ (water solubility) properties Chemical structure:
- An aromatic, lipophilic group
- Partially water soluble to be able to diffuse into the tissues (water solubility) and partially lipophilic to be able to penetrate the lipid membrane of nerves Dissociation constant (pKa) - property of the drug; equivalent pH of which the drugs is 50% ionized and 50 unionized Increase tissue pH free base is higher (increase the lipid solubility) unionized Drecreased tissue ph cation decrease (lipid solubility; ionized Duration of Action (How long?)
- Dependent on diffusion capacity and elimination rate of LA
Duration of Action (How long?)
- Decreased vascularity (Amount of BV) of surrounding tissues, and vasoconstrictor in LA, increase duration Onset of action ability of the drug to take its effect Kinetics: Injection deposition of LA in tissues around the nerve Induction : -Diffusion LA penetrates into the nerve Superficial fasciculi This is affected first during diffusion under induction Some LA is absorbed
