Local Anaesthesia Question and Answers

Local Anaesthesia Important Notes

Local Anaesthesia Classification:

1. Based on the Site of Action:

• Class A: Agents acting on the Exampleternal surface of the membrane: Example- Biotoxins
• Class B: Agents acting on the internal surface of the membrane. Example- Quaternary ammonium compounds
• Class C- Agents acting by independent mechanism- Example- Benzocaine
• Class D- Agents acting by combination mechanisms- Example- Articaine, Bupivacaine

2. Based On Group of Drugs:

• ESTERS

Esters of Benzoic Acids:

• • Butacaine
  • Cocaine
  • HExampleylcaine
  • Tetracaine

Esters of Paraamino Acids:

B Pharmacy Important Questions

• • Chloroquine
  • Procaine
• AMIDES
  • Atricaine
  • Bupivacaine
  • Etidocaine
• Quinolone- Centbucridine

Local Anaesthesia Parts:

• Aromatic lipophilic group
• Hydrophilic amino group
• An intermediate chain

Local Anaesthesia Biotransformation:

• Ester group – hydrolysis by plasma cholinesterases
• Amide group – hydrolysis and hydroxylation by microsomal enzymes of the liver

Local Anaesthesia Safe dose:

• A safe dose of 2% lignocaine is
  • 4.5 mg/kg or 300 mg without vasoconstrictor
  • 7 mg/kg or 500 mg with vasoconstrictor
• Safely dose of adrenaline for dental use
  • In normal patients – 0.2 mg
  • For cardiac patients – 0,04 mg

Safe dose Actions:

B Pharmacy Important Questions

• Anaesthesia of smaller nerve fibres
• Stimulation of CNS
• Produces vasodilatation
• Produces depressant effect on the myocardium

Read And Learn More: Pharmacology Question and Answers

Local Anaesthesia Adverse drug reactions:

• Intolerance
• Cardiovascular depression
• CNS stimulation
• CNS depression
• Malignant hyperpyrExampleia

Local Anaesthesia Uses:

• Surface anaesthesia – for pain due to burns, ulcers and fissures
• Infiltration anaesthesia
• Nerve block anaesthesia
• Spinal anaesthesia
• Systemic use for anti-arrhythmic effect

B Pharmacy Important Questions Local Anaesthesia Long Essays

Question 1. Classify local anaesthetics and write in detail about xylocaine/lignocaine.

Answer:

Local Anaesthetics:

Local anaesthetics are drugs which cause a reversible loss of sensation in the restricted area of the body either by depression in the Excitation of conducting nerves or suppression of Examplecitation of peripheral nerves.

Local Anaesthetics Classification:

1. Based on chemical structure.

• Amides – Lignocaine, mepivacaine.
• Esters.
  • Esters of benzoic acid – Butaaine, cocaine.
  • Esters of para-aminobenzoic acid – chloride- caine.
• Quinolones – Centbucridine.

2. Based on the duration of action.

• Injectable anaesthetics.
  • Low potency and short duration,
    • Procaine, chlorprocain.
  • Intermediate potency and duration.
    • Lignocaine and prilocaine.
  • High potency and long duration.
    • Tetracaine, bupivacaine.
• Surface anaesthetic.
  • Soluble – cocaine, lignocaine, tetracaine.
  • Insoluble – benzocaine, tetracaine.

3. Based on biological site and mode of action.

• Class A
  • Agents acting at receptor site on Exampleternal surface of nerve membrane.
    • Example: biotoxin.
• Class B.
  • Agents act at receptor sites on the internal surface of the nerve membrane.
    • Example: quaternary ammonium compounds.
• Class C.
  • Agents act by a receptor-independent physical-chemical mechanism.
    • Example: Benzocaine.
• Class D.
  • Agents act by a combination of receptor and receptor-independent mechanisms.
    • Examples: Atricaine, lidocaine, mepivacaine.

B Pharmacy Important Questions Local Anaesthetics Mechanism of Action:

Displacement of calcium ions from sodium channel receptor site which permits.
↓
The binding of the LA molecule to this site produces.
↓
Blockade of the sodium channel and decrease in sodium conductance.
↓
Leads to depression in the rate of electrical depolarization.
↓
Failure to achieve the threshold potential level along with.
↓
Lack of development of propagated action potential called.
↓
Conduction Blockade

Xylocaine/Llgnocaine:

• It is the most widely used local anaesthesia.
• It is fast and long-lasting.
• It blocks nerve conduction within 3 min.

B Pharmacy Important Questions Xylocaine/Llgnocaine Actions:

1. Local actions:

• Blocks sensory nerve endings, nerve trunk, neuromuscular junction, ganglionic synapse and receptors.
• Reduces the release of acetylcholine.
• Causes anaesthesia of the skin and paralysis of voluntary muscles.

2. Systemic actions.

• CNS [Central Nervous System]
  • Produces stimulation followed by depression.
  • Causes blood-brain barrier (BBB).
  • Depresses cortical inhibitory pathway.
• Cardiovascular system (CVS).
  • Lignocaine decreases Examplecitability, conduction rate and force of contraction.
  • Causes hypotension due to vasodilatation and myocardial depression.
• Smooth muscles
  • Depresses contraction of intact bowel.

Xylocaine/Llgnocaine Uses:

1. Anaesthesia.

• Used in all types of anaesthesia.

2. Anti-arrhythmia.

Xylocaine/Llgnocaine Adverse Effects:

1. CNS effects.

• Drowsiness, mental clouding, altered tastes, tinnitus.

2. CVS effects.

• Hypotension, bradycardia, cardiac arrhythmia, vascular collapse.

3. Overdose.

• Causes muscle twitching, convulsions, and cardiac arrhythmia.

4. Injections are painful and may delay wound healing.

Question 2. Mention the types of local anaesthetics.

Answer:

Types of Methods of Local Anaesthesia:

Question 3. Classify local anaesthetics. Compare lignocaine and cocaine.

Answer:

local anaesthetics Classification:

Question 4. Explain how the action of lignocaine can be prolonged.

Answer:

Prolonging Action of Lignocaine:

• The action of lignocaine can be prolonged by the addition of adrenaline.
• Adrenaline reduces the rate of absorption of lignocaine from the site to systemic circulation.
• This prolongs the duration of the action.
• It also reduces the systemic toxicity of lignocaine because of its slow absorption.
• As it gets absorbed, it is metabolized.

Question 5. Write a note on the advantages of lignocaine.

Answer:

lignocaine Advantages:

• Most widely used.
• Versatile, used for all types of blocks.
• Fast and long-lasting.
• Blocks nerve conduction within 3 min.
• More intense.
• Its effect last for 30 – 45 min.
• Available in various forms like spray, gel ointment, and injection.
• Cross sensitivity is not seen with it

B Pharmacy Important Questions Local Anaesthesia Short Essays

Question 1. Uses of adrenaline with lignocaine.
(or)
The rationale of combining adrenaline with Lignocaine.

Answer:

Combining adrenaline with lignocaine has some advantages as well as disadvantages.

Lignocaine Advantages:

• Decreases rate of absorption of lignocaine.
• This prolongs its duration of action.
• Reduces systemic toxicity.
• Increases intensity of nerve block.
• Provides a bloodless field for surgery.

Lignocaine Disadvantages:

• Intense vasospasm and ischaemia in the tissues with end arteries cause gangrene.
• Absorption of adrenaline may cause systemic toxicity.
• It may delay wound healing.

Lignocaine Contraindications:

• The adrenaline + lignocaine combination is contraindicated in
• Cardiovascular disorders.
• Hypertension.
• Congestive cardiac failure.
• Ischaemic heart disease.

Question 2. Differentiate between general anaesthesia and local anaesthesia.

Answer:

Question 3. Techniques of local anaesthesia with examples

Answer:

B Pharmacy Important Questions Local Anaesthesia Short Answers

Question 1. Lidocaine/Lignocaine/xylocain.

Answer:

Lidocaine is a long-lasting amide local anaesthetic agent.

• Lidocaine is the most widely used local anaesthetic.
• Lidocaine causes vasodilation in the area of injection.
• Lidocaine is used in all types of blocks.
• Lidocaine is available in various forms.
• Lidocaine effects occur within 3 min and last for 30 – 45 min.
• Lidocaine action can be prolonged by the addition of adrenaline.
• Lidocaine is metabolized in the liver.
• Lidocaine is used in 0.5 – 2% concentration.

Question 2. Cocaine.

Answer:

Cocaine is a natural alkaloid obtained from leaves of Erythroxylon coca.

• Cocaine is an ester local anaesthetic agent.
• Earlier it was used for ocular anaesthesia.
• Cocaine is well observed.
• As Cocaine is a protoplasmic poison, it is never injected.
• In the periphery, it blocks noradrenaline and adrenaline into adrenergic nerve endings.
• Cocaine causes.

1. Local vasoconstriction.
2. Tachycardia.
3. Rise in BP.
4. Mydriasis.

Question 3. Procaine.

Answer:

It is an ester local anaesthetic agent.

• It is the first synthetic local anaesthetic.
• It is metabolized in plasma.
• It is not surface anaesthetic.

Procaine Mechanism:

Hydrolysis of procaine.
↓
Release of para-aminobenzoic acid (PABA)
↓
This antagonises the antibacterial action of sulphonamide.

Question 4. Topical local anaesthetics.

Answer:

• Also known as surface anaesthetics.
• They are available as solutions, ointments, gels, creams, sprays, lozenges, etc.

Topical local anaesthetics Drugs used:

Topical local anaesthetics Uses:

• Applied topically on the mucous membrane of the nose, mouth, eyes, throat, upper respiratory tract, oesophagus, and urethra.
• During endoscopy
• In tonometry of eye.

Question 5. Intravenous anaesthesia.

Answer:

Also known as Bier’s block.

• It allows an extremely rapid induction.
• There is no route of quick elimination like lungs for it
• Thus it is used for induction.
• During it, anaesthesia is maintained by an inhalational agent

 

Question 6. Lidocain and mepivacaine.

Answer: